2 * Definitions for the 'struct sk_buff' memory handlers.
5 * Alan Cox, <gw4pts@gw4pts.ampr.org>
6 * Florian La Roche, <rzsfl@rz.uni-sb.de>
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
14 #ifndef _LINUX_SKBUFF_H
15 #define _LINUX_SKBUFF_H
17 #include <linux/kernel.h>
18 #include <linux/kmemcheck.h>
19 #include <linux/compiler.h>
20 #include <linux/time.h>
21 #include <linux/bug.h>
22 #include <linux/cache.h>
23 #include <linux/rbtree.h>
24 #include <linux/socket.h>
26 #include <linux/atomic.h>
27 #include <asm/types.h>
28 #include <linux/spinlock.h>
29 #include <linux/net.h>
30 #include <linux/textsearch.h>
31 #include <net/checksum.h>
32 #include <linux/rcupdate.h>
33 #include <linux/hrtimer.h>
34 #include <linux/dma-mapping.h>
35 #include <linux/netdev_features.h>
36 #include <linux/sched.h>
37 #include <net/flow_dissector.h>
38 #include <linux/splice.h>
39 #include <linux/in6.h>
40 #include <linux/if_packet.h>
43 /* The interface for checksum offload between the stack and networking drivers
46 * A. IP checksum related features
48 * Drivers advertise checksum offload capabilities in the features of a device.
49 * From the stack's point of view these are capabilities offered by the driver,
50 * a driver typically only advertises features that it is capable of offloading
53 * The checksum related features are:
55 * NETIF_F_HW_CSUM - The driver (or its device) is able to compute one
56 * IP (one's complement) checksum for any combination
57 * of protocols or protocol layering. The checksum is
58 * computed and set in a packet per the CHECKSUM_PARTIAL
59 * interface (see below).
61 * NETIF_F_IP_CSUM - Driver (device) is only able to checksum plain
62 * TCP or UDP packets over IPv4. These are specifically
63 * unencapsulated packets of the form IPv4|TCP or
64 * IPv4|UDP where the Protocol field in the IPv4 header
65 * is TCP or UDP. The IPv4 header may contain IP options
66 * This feature cannot be set in features for a device
67 * with NETIF_F_HW_CSUM also set. This feature is being
68 * DEPRECATED (see below).
70 * NETIF_F_IPV6_CSUM - Driver (device) is only able to checksum plain
71 * TCP or UDP packets over IPv6. These are specifically
72 * unencapsulated packets of the form IPv6|TCP or
73 * IPv4|UDP where the Next Header field in the IPv6
74 * header is either TCP or UDP. IPv6 extension headers
75 * are not supported with this feature. This feature
76 * cannot be set in features for a device with
77 * NETIF_F_HW_CSUM also set. This feature is being
78 * DEPRECATED (see below).
80 * NETIF_F_RXCSUM - Driver (device) performs receive checksum offload.
81 * This flag is used only used to disable the RX checksum
82 * feature for a device. The stack will accept receive
83 * checksum indication in packets received on a device
84 * regardless of whether NETIF_F_RXCSUM is set.
86 * B. Checksumming of received packets by device. Indication of checksum
87 * verification is in set skb->ip_summed. Possible values are:
91 * Device did not checksum this packet e.g. due to lack of capabilities.
92 * The packet contains full (though not verified) checksum in packet but
93 * not in skb->csum. Thus, skb->csum is undefined in this case.
95 * CHECKSUM_UNNECESSARY:
97 * The hardware you're dealing with doesn't calculate the full checksum
98 * (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
99 * for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
100 * if their checksums are okay. skb->csum is still undefined in this case
101 * though. A driver or device must never modify the checksum field in the
102 * packet even if checksum is verified.
104 * CHECKSUM_UNNECESSARY is applicable to following protocols:
105 * TCP: IPv6 and IPv4.
106 * UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
107 * zero UDP checksum for either IPv4 or IPv6, the networking stack
108 * may perform further validation in this case.
109 * GRE: only if the checksum is present in the header.
110 * SCTP: indicates the CRC in SCTP header has been validated.
112 * skb->csum_level indicates the number of consecutive checksums found in
113 * the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
114 * For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
115 * and a device is able to verify the checksums for UDP (possibly zero),
116 * GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
117 * two. If the device were only able to verify the UDP checksum and not
118 * GRE, either because it doesn't support GRE checksum of because GRE
119 * checksum is bad, skb->csum_level would be set to zero (TCP checksum is
120 * not considered in this case).
124 * This is the most generic way. The device supplied checksum of the _whole_
125 * packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
126 * hardware doesn't need to parse L3/L4 headers to implement this.
128 * Note: Even if device supports only some protocols, but is able to produce
129 * skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
133 * A checksum is set up to be offloaded to a device as described in the
134 * output description for CHECKSUM_PARTIAL. This may occur on a packet
135 * received directly from another Linux OS, e.g., a virtualized Linux kernel
136 * on the same host, or it may be set in the input path in GRO or remote
137 * checksum offload. For the purposes of checksum verification, the checksum
138 * referred to by skb->csum_start + skb->csum_offset and any preceding
139 * checksums in the packet are considered verified. Any checksums in the
140 * packet that are after the checksum being offloaded are not considered to
143 * C. Checksumming on transmit for non-GSO. The stack requests checksum offload
144 * in the skb->ip_summed for a packet. Values are:
148 * The driver is required to checksum the packet as seen by hard_start_xmit()
149 * from skb->csum_start up to the end, and to record/write the checksum at
150 * offset skb->csum_start + skb->csum_offset. A driver may verify that the
151 * csum_start and csum_offset values are valid values given the length and
152 * offset of the packet, however they should not attempt to validate that the
153 * checksum refers to a legitimate transport layer checksum-- it is the
154 * purview of the stack to validate that csum_start and csum_offset are set
157 * When the stack requests checksum offload for a packet, the driver MUST
158 * ensure that the checksum is set correctly. A driver can either offload the
159 * checksum calculation to the device, or call skb_checksum_help (in the case
160 * that the device does not support offload for a particular checksum).
162 * NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM are being deprecated in favor of
163 * NETIF_F_HW_CSUM. New devices should use NETIF_F_HW_CSUM to indicate
164 * checksum offload capability. If a device has limited checksum capabilities
165 * (for instance can only perform NETIF_F_IP_CSUM or NETIF_F_IPV6_CSUM as
166 * described above) a helper function can be called to resolve
167 * CHECKSUM_PARTIAL. The helper functions are skb_csum_off_chk*. The helper
168 * function takes a spec argument that describes the protocol layer that is
169 * supported for checksum offload and can be called for each packet. If a
170 * packet does not match the specification for offload, skb_checksum_help
171 * is called to resolve the checksum.
175 * The skb was already checksummed by the protocol, or a checksum is not
178 * CHECKSUM_UNNECESSARY:
180 * This has the same meaning on as CHECKSUM_NONE for checksum offload on
184 * Not used in checksum output. If a driver observes a packet with this value
185 * set in skbuff, if should treat as CHECKSUM_NONE being set.
187 * D. Non-IP checksum (CRC) offloads
189 * NETIF_F_SCTP_CRC - This feature indicates that a device is capable of
190 * offloading the SCTP CRC in a packet. To perform this offload the stack
191 * will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
192 * accordingly. Note the there is no indication in the skbuff that the
193 * CHECKSUM_PARTIAL refers to an SCTP checksum, a driver that supports
194 * both IP checksum offload and SCTP CRC offload must verify which offload
195 * is configured for a packet presumably by inspecting packet headers.
197 * NETIF_F_FCOE_CRC - This feature indicates that a device is capable of
198 * offloading the FCOE CRC in a packet. To perform this offload the stack
199 * will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
200 * accordingly. Note the there is no indication in the skbuff that the
201 * CHECKSUM_PARTIAL refers to an FCOE checksum, a driver that supports
202 * both IP checksum offload and FCOE CRC offload must verify which offload
203 * is configured for a packet presumably by inspecting packet headers.
205 * E. Checksumming on output with GSO.
207 * In the case of a GSO packet (skb_is_gso(skb) is true), checksum offload
208 * is implied by the SKB_GSO_* flags in gso_type. Most obviously, if the
209 * gso_type is SKB_GSO_TCPV4 or SKB_GSO_TCPV6, TCP checksum offload as
210 * part of the GSO operation is implied. If a checksum is being offloaded
211 * with GSO then ip_summed is CHECKSUM_PARTIAL, csum_start and csum_offset
212 * are set to refer to the outermost checksum being offload (two offloaded
213 * checksums are possible with UDP encapsulation).
216 /* Don't change this without changing skb_csum_unnecessary! */
217 #define CHECKSUM_NONE 0
218 #define CHECKSUM_UNNECESSARY 1
219 #define CHECKSUM_COMPLETE 2
220 #define CHECKSUM_PARTIAL 3
222 /* Maximum value in skb->csum_level */
223 #define SKB_MAX_CSUM_LEVEL 3
225 #define SKB_DATA_ALIGN(X) ALIGN(X, SMP_CACHE_BYTES)
226 #define SKB_WITH_OVERHEAD(X) \
227 ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
228 #define SKB_MAX_ORDER(X, ORDER) \
229 SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
230 #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
231 #define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
233 /* return minimum truesize of one skb containing X bytes of data */
234 #define SKB_TRUESIZE(X) ((X) + \
235 SKB_DATA_ALIGN(sizeof(struct sk_buff)) + \
236 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
240 struct pipe_inode_info;
244 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
245 struct nf_conntrack {
250 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
251 struct nf_bridge_info {
254 BRNF_PROTO_UNCHANGED,
262 struct net_device *physindev;
264 /* always valid & non-NULL from FORWARD on, for physdev match */
265 struct net_device *physoutdev;
267 /* prerouting: detect dnat in orig/reply direction */
269 struct in6_addr ipv6_daddr;
271 /* after prerouting + nat detected: store original source
272 * mac since neigh resolution overwrites it, only used while
273 * skb is out in neigh layer.
275 char neigh_header[8];
280 struct sk_buff_head {
281 /* These two members must be first. */
282 struct sk_buff *next;
283 struct sk_buff *prev;
291 /* To allow 64K frame to be packed as single skb without frag_list we
292 * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
293 * buffers which do not start on a page boundary.
295 * Since GRO uses frags we allocate at least 16 regardless of page
298 #if (65536/PAGE_SIZE + 1) < 16
299 #define MAX_SKB_FRAGS 16UL
301 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
303 extern int sysctl_max_skb_frags;
305 /* Set skb_shinfo(skb)->gso_size to this in case you want skb_segment to
306 * segment using its current segmentation instead.
308 #define GSO_BY_FRAGS 0xFFFF
310 typedef struct skb_frag_struct skb_frag_t;
312 struct skb_frag_struct {
316 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
325 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
330 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
335 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
340 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
345 #define HAVE_HW_TIME_STAMP
348 * struct skb_shared_hwtstamps - hardware time stamps
349 * @hwtstamp: hardware time stamp transformed into duration
350 * since arbitrary point in time
352 * Software time stamps generated by ktime_get_real() are stored in
355 * hwtstamps can only be compared against other hwtstamps from
358 * This structure is attached to packets as part of the
359 * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
361 struct skb_shared_hwtstamps {
365 /* Definitions for tx_flags in struct skb_shared_info */
367 /* generate hardware time stamp */
368 SKBTX_HW_TSTAMP = 1 << 0,
370 /* generate software time stamp when queueing packet to NIC */
371 SKBTX_SW_TSTAMP = 1 << 1,
373 /* device driver is going to provide hardware time stamp */
374 SKBTX_IN_PROGRESS = 1 << 2,
376 /* device driver supports TX zero-copy buffers */
377 SKBTX_DEV_ZEROCOPY = 1 << 3,
379 /* generate wifi status information (where possible) */
380 SKBTX_WIFI_STATUS = 1 << 4,
382 /* This indicates at least one fragment might be overwritten
383 * (as in vmsplice(), sendfile() ...)
384 * If we need to compute a TX checksum, we'll need to copy
385 * all frags to avoid possible bad checksum
387 SKBTX_SHARED_FRAG = 1 << 5,
389 /* generate software time stamp when entering packet scheduling */
390 SKBTX_SCHED_TSTAMP = 1 << 6,
393 #define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \
395 #define SKBTX_ANY_TSTAMP (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
398 * The callback notifies userspace to release buffers when skb DMA is done in
399 * lower device, the skb last reference should be 0 when calling this.
400 * The zerocopy_success argument is true if zero copy transmit occurred,
401 * false on data copy or out of memory error caused by data copy attempt.
402 * The ctx field is used to track device context.
403 * The desc field is used to track userspace buffer index.
406 void (*callback)(struct ubuf_info *, bool zerocopy_success);
411 /* This data is invariant across clones and lives at
412 * the end of the header data, ie. at skb->end.
414 struct skb_shared_info {
415 unsigned char nr_frags;
417 unsigned short gso_size;
418 /* Warning: this field is not always filled in (UFO)! */
419 unsigned short gso_segs;
420 unsigned short gso_type;
421 struct sk_buff *frag_list;
422 struct skb_shared_hwtstamps hwtstamps;
427 * Warning : all fields before dataref are cleared in __alloc_skb()
431 /* Intermediate layers must ensure that destructor_arg
432 * remains valid until skb destructor */
433 void * destructor_arg;
435 /* must be last field, see pskb_expand_head() */
436 skb_frag_t frags[MAX_SKB_FRAGS];
439 /* We divide dataref into two halves. The higher 16 bits hold references
440 * to the payload part of skb->data. The lower 16 bits hold references to
441 * the entire skb->data. A clone of a headerless skb holds the length of
442 * the header in skb->hdr_len.
444 * All users must obey the rule that the skb->data reference count must be
445 * greater than or equal to the payload reference count.
447 * Holding a reference to the payload part means that the user does not
448 * care about modifications to the header part of skb->data.
450 #define SKB_DATAREF_SHIFT 16
451 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
455 SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
456 SKB_FCLONE_ORIG, /* orig skb (from fclone_cache) */
457 SKB_FCLONE_CLONE, /* companion fclone skb (from fclone_cache) */
461 SKB_GSO_TCPV4 = 1 << 0,
462 SKB_GSO_UDP = 1 << 1,
464 /* This indicates the skb is from an untrusted source. */
465 SKB_GSO_DODGY = 1 << 2,
467 /* This indicates the tcp segment has CWR set. */
468 SKB_GSO_TCP_ECN = 1 << 3,
470 SKB_GSO_TCP_FIXEDID = 1 << 4,
472 SKB_GSO_TCPV6 = 1 << 5,
474 SKB_GSO_FCOE = 1 << 6,
476 SKB_GSO_GRE = 1 << 7,
478 SKB_GSO_GRE_CSUM = 1 << 8,
480 SKB_GSO_IPXIP4 = 1 << 9,
482 SKB_GSO_IPXIP6 = 1 << 10,
484 SKB_GSO_UDP_TUNNEL = 1 << 11,
486 SKB_GSO_UDP_TUNNEL_CSUM = 1 << 12,
488 SKB_GSO_PARTIAL = 1 << 13,
490 SKB_GSO_TUNNEL_REMCSUM = 1 << 14,
492 SKB_GSO_SCTP = 1 << 15,
495 #if BITS_PER_LONG > 32
496 #define NET_SKBUFF_DATA_USES_OFFSET 1
499 #ifdef NET_SKBUFF_DATA_USES_OFFSET
500 typedef unsigned int sk_buff_data_t;
502 typedef unsigned char *sk_buff_data_t;
506 * struct skb_mstamp - multi resolution time stamps
507 * @stamp_us: timestamp in us resolution
508 * @stamp_jiffies: timestamp in jiffies
521 * skb_mstamp_get - get current timestamp
522 * @cl: place to store timestamps
524 static inline void skb_mstamp_get(struct skb_mstamp *cl)
526 u64 val = local_clock();
528 do_div(val, NSEC_PER_USEC);
529 cl->stamp_us = (u32)val;
530 cl->stamp_jiffies = (u32)jiffies;
534 * skb_mstamp_delta - compute the difference in usec between two skb_mstamp
535 * @t1: pointer to newest sample
536 * @t0: pointer to oldest sample
538 static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
539 const struct skb_mstamp *t0)
541 s32 delta_us = t1->stamp_us - t0->stamp_us;
542 u32 delta_jiffies = t1->stamp_jiffies - t0->stamp_jiffies;
544 /* If delta_us is negative, this might be because interval is too big,
545 * or local_clock() drift is too big : fallback using jiffies.
548 delta_jiffies >= (INT_MAX / (USEC_PER_SEC / HZ)))
550 delta_us = jiffies_to_usecs(delta_jiffies);
555 static inline bool skb_mstamp_after(const struct skb_mstamp *t1,
556 const struct skb_mstamp *t0)
558 s32 diff = t1->stamp_jiffies - t0->stamp_jiffies;
561 diff = t1->stamp_us - t0->stamp_us;
566 * struct sk_buff - socket buffer
567 * @next: Next buffer in list
568 * @prev: Previous buffer in list
569 * @tstamp: Time we arrived/left
570 * @rbnode: RB tree node, alternative to next/prev for netem/tcp
571 * @sk: Socket we are owned by
572 * @dev: Device we arrived on/are leaving by
573 * @cb: Control buffer. Free for use by every layer. Put private vars here
574 * @_skb_refdst: destination entry (with norefcount bit)
575 * @sp: the security path, used for xfrm
576 * @len: Length of actual data
577 * @data_len: Data length
578 * @mac_len: Length of link layer header
579 * @hdr_len: writable header length of cloned skb
580 * @csum: Checksum (must include start/offset pair)
581 * @csum_start: Offset from skb->head where checksumming should start
582 * @csum_offset: Offset from csum_start where checksum should be stored
583 * @priority: Packet queueing priority
584 * @ignore_df: allow local fragmentation
585 * @cloned: Head may be cloned (check refcnt to be sure)
586 * @ip_summed: Driver fed us an IP checksum
587 * @nohdr: Payload reference only, must not modify header
588 * @pkt_type: Packet class
589 * @fclone: skbuff clone status
590 * @ipvs_property: skbuff is owned by ipvs
591 * @tc_skip_classify: do not classify packet. set by IFB device
592 * @tc_at_ingress: used within tc_classify to distinguish in/egress
593 * @tc_redirected: packet was redirected by a tc action
594 * @tc_from_ingress: if tc_redirected, tc_at_ingress at time of redirect
595 * @peeked: this packet has been seen already, so stats have been
596 * done for it, don't do them again
597 * @nf_trace: netfilter packet trace flag
598 * @protocol: Packet protocol from driver
599 * @destructor: Destruct function
600 * @_nfct: Associated connection, if any (with nfctinfo bits)
601 * @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
602 * @skb_iif: ifindex of device we arrived on
603 * @tc_index: Traffic control index
604 * @hash: the packet hash
605 * @queue_mapping: Queue mapping for multiqueue devices
606 * @xmit_more: More SKBs are pending for this queue
607 * @ndisc_nodetype: router type (from link layer)
608 * @ooo_okay: allow the mapping of a socket to a queue to be changed
609 * @l4_hash: indicate hash is a canonical 4-tuple hash over transport
611 * @sw_hash: indicates hash was computed in software stack
612 * @wifi_acked_valid: wifi_acked was set
613 * @wifi_acked: whether frame was acked on wifi or not
614 * @no_fcs: Request NIC to treat last 4 bytes as Ethernet FCS
615 * @dst_pending_confirm: need to confirm neighbour
616 * @napi_id: id of the NAPI struct this skb came from
617 * @secmark: security marking
618 * @mark: Generic packet mark
619 * @vlan_proto: vlan encapsulation protocol
620 * @vlan_tci: vlan tag control information
621 * @inner_protocol: Protocol (encapsulation)
622 * @inner_transport_header: Inner transport layer header (encapsulation)
623 * @inner_network_header: Network layer header (encapsulation)
624 * @inner_mac_header: Link layer header (encapsulation)
625 * @transport_header: Transport layer header
626 * @network_header: Network layer header
627 * @mac_header: Link layer header
628 * @tail: Tail pointer
630 * @head: Head of buffer
631 * @data: Data head pointer
632 * @truesize: Buffer size
633 * @users: User count - see {datagram,tcp}.c
639 /* These two members must be first. */
640 struct sk_buff *next;
641 struct sk_buff *prev;
645 struct skb_mstamp skb_mstamp;
648 struct rb_node rbnode; /* used in netem & tcp stack */
653 struct net_device *dev;
654 /* Some protocols might use this space to store information,
655 * while device pointer would be NULL.
656 * UDP receive path is one user.
658 unsigned long dev_scratch;
661 * This is the control buffer. It is free to use for every
662 * layer. Please put your private variables there. If you
663 * want to keep them across layers you have to do a skb_clone()
664 * first. This is owned by whoever has the skb queued ATM.
666 char cb[48] __aligned(8);
668 unsigned long _skb_refdst;
669 void (*destructor)(struct sk_buff *skb);
673 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
676 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
677 struct nf_bridge_info *nf_bridge;
684 /* Following fields are _not_ copied in __copy_skb_header()
685 * Note that queue_mapping is here mostly to fill a hole.
687 kmemcheck_bitfield_begin(flags1);
690 /* if you move cloned around you also must adapt those constants */
691 #ifdef __BIG_ENDIAN_BITFIELD
692 #define CLONED_MASK (1 << 7)
694 #define CLONED_MASK 1
696 #define CLONED_OFFSET() offsetof(struct sk_buff, __cloned_offset)
698 __u8 __cloned_offset[0];
705 __unused:1; /* one bit hole */
706 kmemcheck_bitfield_end(flags1);
708 /* fields enclosed in headers_start/headers_end are copied
709 * using a single memcpy() in __copy_skb_header()
712 __u32 headers_start[0];
715 /* if you move pkt_type around you also must adapt those constants */
716 #ifdef __BIG_ENDIAN_BITFIELD
717 #define PKT_TYPE_MAX (7 << 5)
719 #define PKT_TYPE_MAX 7
721 #define PKT_TYPE_OFFSET() offsetof(struct sk_buff, __pkt_type_offset)
723 __u8 __pkt_type_offset[0];
733 __u8 wifi_acked_valid:1;
737 /* Indicates the inner headers are valid in the skbuff. */
738 __u8 encapsulation:1;
739 __u8 encap_hdr_csum:1;
741 __u8 csum_complete_sw:1;
745 __u8 dst_pending_confirm:1;
746 #ifdef CONFIG_IPV6_NDISC_NODETYPE
747 __u8 ndisc_nodetype:2;
749 __u8 ipvs_property:1;
750 __u8 inner_protocol_type:1;
751 __u8 remcsum_offload:1;
752 #ifdef CONFIG_NET_SWITCHDEV
753 __u8 offload_fwd_mark:1;
755 #ifdef CONFIG_NET_CLS_ACT
756 __u8 tc_skip_classify:1;
757 __u8 tc_at_ingress:1;
758 __u8 tc_redirected:1;
759 __u8 tc_from_ingress:1;
762 #ifdef CONFIG_NET_SCHED
763 __u16 tc_index; /* traffic control index */
778 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
780 unsigned int napi_id;
781 unsigned int sender_cpu;
784 #ifdef CONFIG_NETWORK_SECMARK
790 __u32 reserved_tailroom;
794 __be16 inner_protocol;
798 __u16 inner_transport_header;
799 __u16 inner_network_header;
800 __u16 inner_mac_header;
803 __u16 transport_header;
804 __u16 network_header;
808 __u32 headers_end[0];
811 /* These elements must be at the end, see alloc_skb() for details. */
816 unsigned int truesize;
822 * Handling routines are only of interest to the kernel
824 #include <linux/slab.h>
827 #define SKB_ALLOC_FCLONE 0x01
828 #define SKB_ALLOC_RX 0x02
829 #define SKB_ALLOC_NAPI 0x04
831 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
832 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
834 return unlikely(skb->pfmemalloc);
838 * skb might have a dst pointer attached, refcounted or not.
839 * _skb_refdst low order bit is set if refcount was _not_ taken
841 #define SKB_DST_NOREF 1UL
842 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
844 #define SKB_NFCT_PTRMASK ~(7UL)
846 * skb_dst - returns skb dst_entry
849 * Returns skb dst_entry, regardless of reference taken or not.
851 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
853 /* If refdst was not refcounted, check we still are in a
854 * rcu_read_lock section
856 WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
857 !rcu_read_lock_held() &&
858 !rcu_read_lock_bh_held());
859 return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
863 * skb_dst_set - sets skb dst
867 * Sets skb dst, assuming a reference was taken on dst and should
868 * be released by skb_dst_drop()
870 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
872 skb->_skb_refdst = (unsigned long)dst;
876 * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
880 * Sets skb dst, assuming a reference was not taken on dst.
881 * If dst entry is cached, we do not take reference and dst_release
882 * will be avoided by refdst_drop. If dst entry is not cached, we take
883 * reference, so that last dst_release can destroy the dst immediately.
885 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
887 WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
888 skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
892 * skb_dst_is_noref - Test if skb dst isn't refcounted
895 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
897 return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
900 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
902 return (struct rtable *)skb_dst(skb);
905 /* For mangling skb->pkt_type from user space side from applications
906 * such as nft, tc, etc, we only allow a conservative subset of
907 * possible pkt_types to be set.
909 static inline bool skb_pkt_type_ok(u32 ptype)
911 return ptype <= PACKET_OTHERHOST;
914 void kfree_skb(struct sk_buff *skb);
915 void kfree_skb_list(struct sk_buff *segs);
916 void skb_tx_error(struct sk_buff *skb);
917 void consume_skb(struct sk_buff *skb);
918 void __kfree_skb(struct sk_buff *skb);
919 extern struct kmem_cache *skbuff_head_cache;
921 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
922 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
923 bool *fragstolen, int *delta_truesize);
925 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
927 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
928 struct sk_buff *build_skb(void *data, unsigned int frag_size);
929 static inline struct sk_buff *alloc_skb(unsigned int size,
932 return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
935 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
936 unsigned long data_len,
941 /* Layout of fast clones : [skb1][skb2][fclone_ref] */
942 struct sk_buff_fclones {
951 * skb_fclone_busy - check if fclone is busy
955 * Returns true if skb is a fast clone, and its clone is not freed.
956 * Some drivers call skb_orphan() in their ndo_start_xmit(),
957 * so we also check that this didnt happen.
959 static inline bool skb_fclone_busy(const struct sock *sk,
960 const struct sk_buff *skb)
962 const struct sk_buff_fclones *fclones;
964 fclones = container_of(skb, struct sk_buff_fclones, skb1);
966 return skb->fclone == SKB_FCLONE_ORIG &&
967 atomic_read(&fclones->fclone_ref) > 1 &&
968 fclones->skb2.sk == sk;
971 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
974 return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
977 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
978 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
980 return __alloc_skb_head(priority, -1);
983 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
984 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
985 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
986 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
987 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
988 gfp_t gfp_mask, bool fclone);
989 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
992 return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
995 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
996 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
997 unsigned int headroom);
998 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
999 int newtailroom, gfp_t priority);
1000 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
1001 int offset, int len);
1002 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
1004 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
1005 int skb_pad(struct sk_buff *skb, int pad);
1006 #define dev_kfree_skb(a) consume_skb(a)
1008 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
1009 int getfrag(void *from, char *to, int offset,
1010 int len, int odd, struct sk_buff *skb),
1011 void *from, int length);
1013 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
1014 int offset, size_t size);
1016 struct skb_seq_state {
1020 __u32 stepped_offset;
1021 struct sk_buff *root_skb;
1022 struct sk_buff *cur_skb;
1026 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
1027 unsigned int to, struct skb_seq_state *st);
1028 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
1029 struct skb_seq_state *st);
1030 void skb_abort_seq_read(struct skb_seq_state *st);
1032 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
1033 unsigned int to, struct ts_config *config);
1036 * Packet hash types specify the type of hash in skb_set_hash.
1038 * Hash types refer to the protocol layer addresses which are used to
1039 * construct a packet's hash. The hashes are used to differentiate or identify
1040 * flows of the protocol layer for the hash type. Hash types are either
1041 * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
1043 * Properties of hashes:
1045 * 1) Two packets in different flows have different hash values
1046 * 2) Two packets in the same flow should have the same hash value
1048 * A hash at a higher layer is considered to be more specific. A driver should
1049 * set the most specific hash possible.
1051 * A driver cannot indicate a more specific hash than the layer at which a hash
1052 * was computed. For instance an L3 hash cannot be set as an L4 hash.
1054 * A driver may indicate a hash level which is less specific than the
1055 * actual layer the hash was computed on. For instance, a hash computed
1056 * at L4 may be considered an L3 hash. This should only be done if the
1057 * driver can't unambiguously determine that the HW computed the hash at
1058 * the higher layer. Note that the "should" in the second property above
1061 enum pkt_hash_types {
1062 PKT_HASH_TYPE_NONE, /* Undefined type */
1063 PKT_HASH_TYPE_L2, /* Input: src_MAC, dest_MAC */
1064 PKT_HASH_TYPE_L3, /* Input: src_IP, dst_IP */
1065 PKT_HASH_TYPE_L4, /* Input: src_IP, dst_IP, src_port, dst_port */
1068 static inline void skb_clear_hash(struct sk_buff *skb)
1075 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
1078 skb_clear_hash(skb);
1082 __skb_set_hash(struct sk_buff *skb, __u32 hash, bool is_sw, bool is_l4)
1084 skb->l4_hash = is_l4;
1085 skb->sw_hash = is_sw;
1090 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
1092 /* Used by drivers to set hash from HW */
1093 __skb_set_hash(skb, hash, false, type == PKT_HASH_TYPE_L4);
1097 __skb_set_sw_hash(struct sk_buff *skb, __u32 hash, bool is_l4)
1099 __skb_set_hash(skb, hash, true, is_l4);
1102 void __skb_get_hash(struct sk_buff *skb);
1103 u32 __skb_get_hash_symmetric(const struct sk_buff *skb);
1104 u32 skb_get_poff(const struct sk_buff *skb);
1105 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
1106 const struct flow_keys *keys, int hlen);
1107 __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
1108 void *data, int hlen_proto);
1110 static inline __be32 skb_flow_get_ports(const struct sk_buff *skb,
1111 int thoff, u8 ip_proto)
1113 return __skb_flow_get_ports(skb, thoff, ip_proto, NULL, 0);
1116 void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
1117 const struct flow_dissector_key *key,
1118 unsigned int key_count);
1120 bool __skb_flow_dissect(const struct sk_buff *skb,
1121 struct flow_dissector *flow_dissector,
1122 void *target_container,
1123 void *data, __be16 proto, int nhoff, int hlen,
1124 unsigned int flags);
1126 static inline bool skb_flow_dissect(const struct sk_buff *skb,
1127 struct flow_dissector *flow_dissector,
1128 void *target_container, unsigned int flags)
1130 return __skb_flow_dissect(skb, flow_dissector, target_container,
1131 NULL, 0, 0, 0, flags);
1134 static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb,
1135 struct flow_keys *flow,
1138 memset(flow, 0, sizeof(*flow));
1139 return __skb_flow_dissect(skb, &flow_keys_dissector, flow,
1140 NULL, 0, 0, 0, flags);
1143 static inline bool skb_flow_dissect_flow_keys_buf(struct flow_keys *flow,
1144 void *data, __be16 proto,
1145 int nhoff, int hlen,
1148 memset(flow, 0, sizeof(*flow));
1149 return __skb_flow_dissect(NULL, &flow_keys_buf_dissector, flow,
1150 data, proto, nhoff, hlen, flags);
1153 static inline __u32 skb_get_hash(struct sk_buff *skb)
1155 if (!skb->l4_hash && !skb->sw_hash)
1156 __skb_get_hash(skb);
1161 __u32 __skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6);
1163 static inline __u32 skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6)
1165 if (!skb->l4_hash && !skb->sw_hash) {
1166 struct flow_keys keys;
1167 __u32 hash = __get_hash_from_flowi6(fl6, &keys);
1169 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1175 __u32 __skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl);
1177 static inline __u32 skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl4)
1179 if (!skb->l4_hash && !skb->sw_hash) {
1180 struct flow_keys keys;
1181 __u32 hash = __get_hash_from_flowi4(fl4, &keys);
1183 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1189 __u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb);
1191 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
1196 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
1198 to->hash = from->hash;
1199 to->sw_hash = from->sw_hash;
1200 to->l4_hash = from->l4_hash;
1203 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1204 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1206 return skb->head + skb->end;
1209 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1214 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1219 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1221 return skb->end - skb->head;
1226 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
1228 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
1230 return &skb_shinfo(skb)->hwtstamps;
1234 * skb_queue_empty - check if a queue is empty
1237 * Returns true if the queue is empty, false otherwise.
1239 static inline int skb_queue_empty(const struct sk_buff_head *list)
1241 return list->next == (const struct sk_buff *) list;
1245 * skb_queue_is_last - check if skb is the last entry in the queue
1249 * Returns true if @skb is the last buffer on the list.
1251 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
1252 const struct sk_buff *skb)
1254 return skb->next == (const struct sk_buff *) list;
1258 * skb_queue_is_first - check if skb is the first entry in the queue
1262 * Returns true if @skb is the first buffer on the list.
1264 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
1265 const struct sk_buff *skb)
1267 return skb->prev == (const struct sk_buff *) list;
1271 * skb_queue_next - return the next packet in the queue
1273 * @skb: current buffer
1275 * Return the next packet in @list after @skb. It is only valid to
1276 * call this if skb_queue_is_last() evaluates to false.
1278 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
1279 const struct sk_buff *skb)
1281 /* This BUG_ON may seem severe, but if we just return then we
1282 * are going to dereference garbage.
1284 BUG_ON(skb_queue_is_last(list, skb));
1289 * skb_queue_prev - return the prev packet in the queue
1291 * @skb: current buffer
1293 * Return the prev packet in @list before @skb. It is only valid to
1294 * call this if skb_queue_is_first() evaluates to false.
1296 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
1297 const struct sk_buff *skb)
1299 /* This BUG_ON may seem severe, but if we just return then we
1300 * are going to dereference garbage.
1302 BUG_ON(skb_queue_is_first(list, skb));
1307 * skb_get - reference buffer
1308 * @skb: buffer to reference
1310 * Makes another reference to a socket buffer and returns a pointer
1313 static inline struct sk_buff *skb_get(struct sk_buff *skb)
1315 atomic_inc(&skb->users);
1320 * If users == 1, we are the only owner and are can avoid redundant
1325 * skb_cloned - is the buffer a clone
1326 * @skb: buffer to check
1328 * Returns true if the buffer was generated with skb_clone() and is
1329 * one of multiple shared copies of the buffer. Cloned buffers are
1330 * shared data so must not be written to under normal circumstances.
1332 static inline int skb_cloned(const struct sk_buff *skb)
1334 return skb->cloned &&
1335 (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1338 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1340 might_sleep_if(gfpflags_allow_blocking(pri));
1342 if (skb_cloned(skb))
1343 return pskb_expand_head(skb, 0, 0, pri);
1349 * skb_header_cloned - is the header a clone
1350 * @skb: buffer to check
1352 * Returns true if modifying the header part of the buffer requires
1353 * the data to be copied.
1355 static inline int skb_header_cloned(const struct sk_buff *skb)
1362 dataref = atomic_read(&skb_shinfo(skb)->dataref);
1363 dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1364 return dataref != 1;
1367 static inline int skb_header_unclone(struct sk_buff *skb, gfp_t pri)
1369 might_sleep_if(gfpflags_allow_blocking(pri));
1371 if (skb_header_cloned(skb))
1372 return pskb_expand_head(skb, 0, 0, pri);
1378 * skb_header_release - release reference to header
1379 * @skb: buffer to operate on
1381 * Drop a reference to the header part of the buffer. This is done
1382 * by acquiring a payload reference. You must not read from the header
1383 * part of skb->data after this.
1384 * Note : Check if you can use __skb_header_release() instead.
1386 static inline void skb_header_release(struct sk_buff *skb)
1390 atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
1394 * __skb_header_release - release reference to header
1395 * @skb: buffer to operate on
1397 * Variant of skb_header_release() assuming skb is private to caller.
1398 * We can avoid one atomic operation.
1400 static inline void __skb_header_release(struct sk_buff *skb)
1403 atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT));
1408 * skb_shared - is the buffer shared
1409 * @skb: buffer to check
1411 * Returns true if more than one person has a reference to this
1414 static inline int skb_shared(const struct sk_buff *skb)
1416 return atomic_read(&skb->users) != 1;
1420 * skb_share_check - check if buffer is shared and if so clone it
1421 * @skb: buffer to check
1422 * @pri: priority for memory allocation
1424 * If the buffer is shared the buffer is cloned and the old copy
1425 * drops a reference. A new clone with a single reference is returned.
1426 * If the buffer is not shared the original buffer is returned. When
1427 * being called from interrupt status or with spinlocks held pri must
1430 * NULL is returned on a memory allocation failure.
1432 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1434 might_sleep_if(gfpflags_allow_blocking(pri));
1435 if (skb_shared(skb)) {
1436 struct sk_buff *nskb = skb_clone(skb, pri);
1448 * Copy shared buffers into a new sk_buff. We effectively do COW on
1449 * packets to handle cases where we have a local reader and forward
1450 * and a couple of other messy ones. The normal one is tcpdumping
1451 * a packet thats being forwarded.
1455 * skb_unshare - make a copy of a shared buffer
1456 * @skb: buffer to check
1457 * @pri: priority for memory allocation
1459 * If the socket buffer is a clone then this function creates a new
1460 * copy of the data, drops a reference count on the old copy and returns
1461 * the new copy with the reference count at 1. If the buffer is not a clone
1462 * the original buffer is returned. When called with a spinlock held or
1463 * from interrupt state @pri must be %GFP_ATOMIC
1465 * %NULL is returned on a memory allocation failure.
1467 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1470 might_sleep_if(gfpflags_allow_blocking(pri));
1471 if (skb_cloned(skb)) {
1472 struct sk_buff *nskb = skb_copy(skb, pri);
1474 /* Free our shared copy */
1485 * skb_peek - peek at the head of an &sk_buff_head
1486 * @list_: list to peek at
1488 * Peek an &sk_buff. Unlike most other operations you _MUST_
1489 * be careful with this one. A peek leaves the buffer on the
1490 * list and someone else may run off with it. You must hold
1491 * the appropriate locks or have a private queue to do this.
1493 * Returns %NULL for an empty list or a pointer to the head element.
1494 * The reference count is not incremented and the reference is therefore
1495 * volatile. Use with caution.
1497 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1499 struct sk_buff *skb = list_->next;
1501 if (skb == (struct sk_buff *)list_)
1507 * skb_peek_next - peek skb following the given one from a queue
1508 * @skb: skb to start from
1509 * @list_: list to peek at
1511 * Returns %NULL when the end of the list is met or a pointer to the
1512 * next element. The reference count is not incremented and the
1513 * reference is therefore volatile. Use with caution.
1515 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1516 const struct sk_buff_head *list_)
1518 struct sk_buff *next = skb->next;
1520 if (next == (struct sk_buff *)list_)
1526 * skb_peek_tail - peek at the tail of an &sk_buff_head
1527 * @list_: list to peek at
1529 * Peek an &sk_buff. Unlike most other operations you _MUST_
1530 * be careful with this one. A peek leaves the buffer on the
1531 * list and someone else may run off with it. You must hold
1532 * the appropriate locks or have a private queue to do this.
1534 * Returns %NULL for an empty list or a pointer to the tail element.
1535 * The reference count is not incremented and the reference is therefore
1536 * volatile. Use with caution.
1538 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1540 struct sk_buff *skb = list_->prev;
1542 if (skb == (struct sk_buff *)list_)
1549 * skb_queue_len - get queue length
1550 * @list_: list to measure
1552 * Return the length of an &sk_buff queue.
1554 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1560 * __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1561 * @list: queue to initialize
1563 * This initializes only the list and queue length aspects of
1564 * an sk_buff_head object. This allows to initialize the list
1565 * aspects of an sk_buff_head without reinitializing things like
1566 * the spinlock. It can also be used for on-stack sk_buff_head
1567 * objects where the spinlock is known to not be used.
1569 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1571 list->prev = list->next = (struct sk_buff *)list;
1576 * This function creates a split out lock class for each invocation;
1577 * this is needed for now since a whole lot of users of the skb-queue
1578 * infrastructure in drivers have different locking usage (in hardirq)
1579 * than the networking core (in softirq only). In the long run either the
1580 * network layer or drivers should need annotation to consolidate the
1581 * main types of usage into 3 classes.
1583 static inline void skb_queue_head_init(struct sk_buff_head *list)
1585 spin_lock_init(&list->lock);
1586 __skb_queue_head_init(list);
1589 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1590 struct lock_class_key *class)
1592 skb_queue_head_init(list);
1593 lockdep_set_class(&list->lock, class);
1597 * Insert an sk_buff on a list.
1599 * The "__skb_xxxx()" functions are the non-atomic ones that
1600 * can only be called with interrupts disabled.
1602 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1603 struct sk_buff_head *list);
1604 static inline void __skb_insert(struct sk_buff *newsk,
1605 struct sk_buff *prev, struct sk_buff *next,
1606 struct sk_buff_head *list)
1610 next->prev = prev->next = newsk;
1614 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1615 struct sk_buff *prev,
1616 struct sk_buff *next)
1618 struct sk_buff *first = list->next;
1619 struct sk_buff *last = list->prev;
1629 * skb_queue_splice - join two skb lists, this is designed for stacks
1630 * @list: the new list to add
1631 * @head: the place to add it in the first list
1633 static inline void skb_queue_splice(const struct sk_buff_head *list,
1634 struct sk_buff_head *head)
1636 if (!skb_queue_empty(list)) {
1637 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1638 head->qlen += list->qlen;
1643 * skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1644 * @list: the new list to add
1645 * @head: the place to add it in the first list
1647 * The list at @list is reinitialised
1649 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1650 struct sk_buff_head *head)
1652 if (!skb_queue_empty(list)) {
1653 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1654 head->qlen += list->qlen;
1655 __skb_queue_head_init(list);
1660 * skb_queue_splice_tail - join two skb lists, each list being a queue
1661 * @list: the new list to add
1662 * @head: the place to add it in the first list
1664 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1665 struct sk_buff_head *head)
1667 if (!skb_queue_empty(list)) {
1668 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1669 head->qlen += list->qlen;
1674 * skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1675 * @list: the new list to add
1676 * @head: the place to add it in the first list
1678 * Each of the lists is a queue.
1679 * The list at @list is reinitialised
1681 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1682 struct sk_buff_head *head)
1684 if (!skb_queue_empty(list)) {
1685 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1686 head->qlen += list->qlen;
1687 __skb_queue_head_init(list);
1692 * __skb_queue_after - queue a buffer at the list head
1693 * @list: list to use
1694 * @prev: place after this buffer
1695 * @newsk: buffer to queue
1697 * Queue a buffer int the middle of a list. This function takes no locks
1698 * and you must therefore hold required locks before calling it.
1700 * A buffer cannot be placed on two lists at the same time.
1702 static inline void __skb_queue_after(struct sk_buff_head *list,
1703 struct sk_buff *prev,
1704 struct sk_buff *newsk)
1706 __skb_insert(newsk, prev, prev->next, list);
1709 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1710 struct sk_buff_head *list);
1712 static inline void __skb_queue_before(struct sk_buff_head *list,
1713 struct sk_buff *next,
1714 struct sk_buff *newsk)
1716 __skb_insert(newsk, next->prev, next, list);
1720 * __skb_queue_head - queue a buffer at the list head
1721 * @list: list to use
1722 * @newsk: buffer to queue
1724 * Queue a buffer at the start of a list. This function takes no locks
1725 * and you must therefore hold required locks before calling it.
1727 * A buffer cannot be placed on two lists at the same time.
1729 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1730 static inline void __skb_queue_head(struct sk_buff_head *list,
1731 struct sk_buff *newsk)
1733 __skb_queue_after(list, (struct sk_buff *)list, newsk);
1737 * __skb_queue_tail - queue a buffer at the list tail
1738 * @list: list to use
1739 * @newsk: buffer to queue
1741 * Queue a buffer at the end of a list. This function takes no locks
1742 * and you must therefore hold required locks before calling it.
1744 * A buffer cannot be placed on two lists at the same time.
1746 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1747 static inline void __skb_queue_tail(struct sk_buff_head *list,
1748 struct sk_buff *newsk)
1750 __skb_queue_before(list, (struct sk_buff *)list, newsk);
1754 * remove sk_buff from list. _Must_ be called atomically, and with
1757 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1758 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1760 struct sk_buff *next, *prev;
1765 skb->next = skb->prev = NULL;
1771 * __skb_dequeue - remove from the head of the queue
1772 * @list: list to dequeue from
1774 * Remove the head of the list. This function does not take any locks
1775 * so must be used with appropriate locks held only. The head item is
1776 * returned or %NULL if the list is empty.
1778 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1779 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1781 struct sk_buff *skb = skb_peek(list);
1783 __skb_unlink(skb, list);
1788 * __skb_dequeue_tail - remove from the tail of the queue
1789 * @list: list to dequeue from
1791 * Remove the tail of the list. This function does not take any locks
1792 * so must be used with appropriate locks held only. The tail item is
1793 * returned or %NULL if the list is empty.
1795 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1796 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1798 struct sk_buff *skb = skb_peek_tail(list);
1800 __skb_unlink(skb, list);
1805 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1807 return skb->data_len;
1810 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1812 return skb->len - skb->data_len;
1815 static inline unsigned int skb_pagelen(const struct sk_buff *skb)
1817 unsigned int i, len = 0;
1819 for (i = skb_shinfo(skb)->nr_frags - 1; (int)i >= 0; i--)
1820 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1821 return len + skb_headlen(skb);
1825 * __skb_fill_page_desc - initialise a paged fragment in an skb
1826 * @skb: buffer containing fragment to be initialised
1827 * @i: paged fragment index to initialise
1828 * @page: the page to use for this fragment
1829 * @off: the offset to the data with @page
1830 * @size: the length of the data
1832 * Initialises the @i'th fragment of @skb to point to &size bytes at
1833 * offset @off within @page.
1835 * Does not take any additional reference on the fragment.
1837 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1838 struct page *page, int off, int size)
1840 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1843 * Propagate page pfmemalloc to the skb if we can. The problem is
1844 * that not all callers have unique ownership of the page but rely
1845 * on page_is_pfmemalloc doing the right thing(tm).
1847 frag->page.p = page;
1848 frag->page_offset = off;
1849 skb_frag_size_set(frag, size);
1851 page = compound_head(page);
1852 if (page_is_pfmemalloc(page))
1853 skb->pfmemalloc = true;
1857 * skb_fill_page_desc - initialise a paged fragment in an skb
1858 * @skb: buffer containing fragment to be initialised
1859 * @i: paged fragment index to initialise
1860 * @page: the page to use for this fragment
1861 * @off: the offset to the data with @page
1862 * @size: the length of the data
1864 * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1865 * @skb to point to @size bytes at offset @off within @page. In
1866 * addition updates @skb such that @i is the last fragment.
1868 * Does not take any additional reference on the fragment.
1870 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1871 struct page *page, int off, int size)
1873 __skb_fill_page_desc(skb, i, page, off, size);
1874 skb_shinfo(skb)->nr_frags = i + 1;
1877 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1878 int size, unsigned int truesize);
1880 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1881 unsigned int truesize);
1883 #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags)
1884 #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_has_frag_list(skb))
1885 #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb))
1887 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1888 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1890 return skb->head + skb->tail;
1893 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1895 skb->tail = skb->data - skb->head;
1898 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1900 skb_reset_tail_pointer(skb);
1901 skb->tail += offset;
1904 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1905 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1910 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1912 skb->tail = skb->data;
1915 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1917 skb->tail = skb->data + offset;
1920 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1923 * Add data to an sk_buff
1925 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1926 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1927 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1929 unsigned char *tmp = skb_tail_pointer(skb);
1930 SKB_LINEAR_ASSERT(skb);
1936 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1937 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1944 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1945 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1948 BUG_ON(skb->len < skb->data_len);
1949 return skb->data += len;
1952 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1954 return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1957 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1959 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1961 if (len > skb_headlen(skb) &&
1962 !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1965 return skb->data += len;
1968 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1970 return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1973 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1975 if (likely(len <= skb_headlen(skb)))
1977 if (unlikely(len > skb->len))
1979 return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1982 void skb_condense(struct sk_buff *skb);
1985 * skb_headroom - bytes at buffer head
1986 * @skb: buffer to check
1988 * Return the number of bytes of free space at the head of an &sk_buff.
1990 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1992 return skb->data - skb->head;
1996 * skb_tailroom - bytes at buffer end
1997 * @skb: buffer to check
1999 * Return the number of bytes of free space at the tail of an sk_buff
2001 static inline int skb_tailroom(const struct sk_buff *skb)
2003 return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
2007 * skb_availroom - bytes at buffer end
2008 * @skb: buffer to check
2010 * Return the number of bytes of free space at the tail of an sk_buff
2011 * allocated by sk_stream_alloc()
2013 static inline int skb_availroom(const struct sk_buff *skb)
2015 if (skb_is_nonlinear(skb))
2018 return skb->end - skb->tail - skb->reserved_tailroom;
2022 * skb_reserve - adjust headroom
2023 * @skb: buffer to alter
2024 * @len: bytes to move
2026 * Increase the headroom of an empty &sk_buff by reducing the tail
2027 * room. This is only allowed for an empty buffer.
2029 static inline void skb_reserve(struct sk_buff *skb, int len)
2036 * skb_tailroom_reserve - adjust reserved_tailroom
2037 * @skb: buffer to alter
2038 * @mtu: maximum amount of headlen permitted
2039 * @needed_tailroom: minimum amount of reserved_tailroom
2041 * Set reserved_tailroom so that headlen can be as large as possible but
2042 * not larger than mtu and tailroom cannot be smaller than
2044 * The required headroom should already have been reserved before using
2047 static inline void skb_tailroom_reserve(struct sk_buff *skb, unsigned int mtu,
2048 unsigned int needed_tailroom)
2050 SKB_LINEAR_ASSERT(skb);
2051 if (mtu < skb_tailroom(skb) - needed_tailroom)
2052 /* use at most mtu */
2053 skb->reserved_tailroom = skb_tailroom(skb) - mtu;
2055 /* use up to all available space */
2056 skb->reserved_tailroom = needed_tailroom;
2059 #define ENCAP_TYPE_ETHER 0
2060 #define ENCAP_TYPE_IPPROTO 1
2062 static inline void skb_set_inner_protocol(struct sk_buff *skb,
2065 skb->inner_protocol = protocol;
2066 skb->inner_protocol_type = ENCAP_TYPE_ETHER;
2069 static inline void skb_set_inner_ipproto(struct sk_buff *skb,
2072 skb->inner_ipproto = ipproto;
2073 skb->inner_protocol_type = ENCAP_TYPE_IPPROTO;
2076 static inline void skb_reset_inner_headers(struct sk_buff *skb)
2078 skb->inner_mac_header = skb->mac_header;
2079 skb->inner_network_header = skb->network_header;
2080 skb->inner_transport_header = skb->transport_header;
2083 static inline void skb_reset_mac_len(struct sk_buff *skb)
2085 skb->mac_len = skb->network_header - skb->mac_header;
2088 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
2091 return skb->head + skb->inner_transport_header;
2094 static inline int skb_inner_transport_offset(const struct sk_buff *skb)
2096 return skb_inner_transport_header(skb) - skb->data;
2099 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
2101 skb->inner_transport_header = skb->data - skb->head;
2104 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
2107 skb_reset_inner_transport_header(skb);
2108 skb->inner_transport_header += offset;
2111 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
2113 return skb->head + skb->inner_network_header;
2116 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
2118 skb->inner_network_header = skb->data - skb->head;
2121 static inline void skb_set_inner_network_header(struct sk_buff *skb,
2124 skb_reset_inner_network_header(skb);
2125 skb->inner_network_header += offset;
2128 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
2130 return skb->head + skb->inner_mac_header;
2133 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
2135 skb->inner_mac_header = skb->data - skb->head;
2138 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
2141 skb_reset_inner_mac_header(skb);
2142 skb->inner_mac_header += offset;
2144 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
2146 return skb->transport_header != (typeof(skb->transport_header))~0U;
2149 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
2151 return skb->head + skb->transport_header;
2154 static inline void skb_reset_transport_header(struct sk_buff *skb)
2156 skb->transport_header = skb->data - skb->head;
2159 static inline void skb_set_transport_header(struct sk_buff *skb,
2162 skb_reset_transport_header(skb);
2163 skb->transport_header += offset;
2166 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
2168 return skb->head + skb->network_header;
2171 static inline void skb_reset_network_header(struct sk_buff *skb)
2173 skb->network_header = skb->data - skb->head;
2176 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
2178 skb_reset_network_header(skb);
2179 skb->network_header += offset;
2182 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
2184 return skb->head + skb->mac_header;
2187 static inline int skb_mac_offset(const struct sk_buff *skb)
2189 return skb_mac_header(skb) - skb->data;
2192 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
2194 return skb->mac_header != (typeof(skb->mac_header))~0U;
2197 static inline void skb_reset_mac_header(struct sk_buff *skb)
2199 skb->mac_header = skb->data - skb->head;
2202 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
2204 skb_reset_mac_header(skb);
2205 skb->mac_header += offset;
2208 static inline void skb_pop_mac_header(struct sk_buff *skb)
2210 skb->mac_header = skb->network_header;
2213 static inline void skb_probe_transport_header(struct sk_buff *skb,
2214 const int offset_hint)
2216 struct flow_keys keys;
2218 if (skb_transport_header_was_set(skb))
2220 else if (skb_flow_dissect_flow_keys(skb, &keys, 0))
2221 skb_set_transport_header(skb, keys.control.thoff);
2223 skb_set_transport_header(skb, offset_hint);
2226 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
2228 if (skb_mac_header_was_set(skb)) {
2229 const unsigned char *old_mac = skb_mac_header(skb);
2231 skb_set_mac_header(skb, -skb->mac_len);
2232 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
2236 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
2238 return skb->csum_start - skb_headroom(skb);
2241 static inline unsigned char *skb_checksum_start(const struct sk_buff *skb)
2243 return skb->head + skb->csum_start;
2246 static inline int skb_transport_offset(const struct sk_buff *skb)
2248 return skb_transport_header(skb) - skb->data;
2251 static inline u32 skb_network_header_len(const struct sk_buff *skb)
2253 return skb->transport_header - skb->network_header;
2256 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
2258 return skb->inner_transport_header - skb->inner_network_header;
2261 static inline int skb_network_offset(const struct sk_buff *skb)
2263 return skb_network_header(skb) - skb->data;
2266 static inline int skb_inner_network_offset(const struct sk_buff *skb)
2268 return skb_inner_network_header(skb) - skb->data;
2271 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
2273 return pskb_may_pull(skb, skb_network_offset(skb) + len);
2277 * CPUs often take a performance hit when accessing unaligned memory
2278 * locations. The actual performance hit varies, it can be small if the
2279 * hardware handles it or large if we have to take an exception and fix it
2282 * Since an ethernet header is 14 bytes network drivers often end up with
2283 * the IP header at an unaligned offset. The IP header can be aligned by
2284 * shifting the start of the packet by 2 bytes. Drivers should do this
2287 * skb_reserve(skb, NET_IP_ALIGN);
2289 * The downside to this alignment of the IP header is that the DMA is now
2290 * unaligned. On some architectures the cost of an unaligned DMA is high
2291 * and this cost outweighs the gains made by aligning the IP header.
2293 * Since this trade off varies between architectures, we allow NET_IP_ALIGN
2296 #ifndef NET_IP_ALIGN
2297 #define NET_IP_ALIGN 2
2301 * The networking layer reserves some headroom in skb data (via
2302 * dev_alloc_skb). This is used to avoid having to reallocate skb data when
2303 * the header has to grow. In the default case, if the header has to grow
2304 * 32 bytes or less we avoid the reallocation.
2306 * Unfortunately this headroom changes the DMA alignment of the resulting
2307 * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
2308 * on some architectures. An architecture can override this value,
2309 * perhaps setting it to a cacheline in size (since that will maintain
2310 * cacheline alignment of the DMA). It must be a power of 2.
2312 * Various parts of the networking layer expect at least 32 bytes of
2313 * headroom, you should not reduce this.
2315 * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
2316 * to reduce average number of cache lines per packet.
2317 * get_rps_cpus() for example only access one 64 bytes aligned block :
2318 * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
2321 #define NET_SKB_PAD max(32, L1_CACHE_BYTES)
2324 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2326 static inline void __skb_set_length(struct sk_buff *skb, unsigned int len)
2328 if (unlikely(skb_is_nonlinear(skb))) {
2333 skb_set_tail_pointer(skb, len);
2336 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
2338 __skb_set_length(skb, len);
2341 void skb_trim(struct sk_buff *skb, unsigned int len);
2343 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
2346 return ___pskb_trim(skb, len);
2347 __skb_trim(skb, len);
2351 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
2353 return (len < skb->len) ? __pskb_trim(skb, len) : 0;
2357 * pskb_trim_unique - remove end from a paged unique (not cloned) buffer
2358 * @skb: buffer to alter
2361 * This is identical to pskb_trim except that the caller knows that
2362 * the skb is not cloned so we should never get an error due to out-
2365 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
2367 int err = pskb_trim(skb, len);
2371 static inline int __skb_grow(struct sk_buff *skb, unsigned int len)
2373 unsigned int diff = len - skb->len;
2375 if (skb_tailroom(skb) < diff) {
2376 int ret = pskb_expand_head(skb, 0, diff - skb_tailroom(skb),
2381 __skb_set_length(skb, len);
2386 * skb_orphan - orphan a buffer
2387 * @skb: buffer to orphan
2389 * If a buffer currently has an owner then we call the owner's
2390 * destructor function and make the @skb unowned. The buffer continues
2391 * to exist but is no longer charged to its former owner.
2393 static inline void skb_orphan(struct sk_buff *skb)
2395 if (skb->destructor) {
2396 skb->destructor(skb);
2397 skb->destructor = NULL;
2405 * skb_orphan_frags - orphan the frags contained in a buffer
2406 * @skb: buffer to orphan frags from
2407 * @gfp_mask: allocation mask for replacement pages
2409 * For each frag in the SKB which needs a destructor (i.e. has an
2410 * owner) create a copy of that frag and release the original
2411 * page by calling the destructor.
2413 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
2415 if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
2417 return skb_copy_ubufs(skb, gfp_mask);
2421 * __skb_queue_purge - empty a list
2422 * @list: list to empty
2424 * Delete all buffers on an &sk_buff list. Each buffer is removed from
2425 * the list and one reference dropped. This function does not take the
2426 * list lock and the caller must hold the relevant locks to use it.
2428 void skb_queue_purge(struct sk_buff_head *list);
2429 static inline void __skb_queue_purge(struct sk_buff_head *list)
2431 struct sk_buff *skb;
2432 while ((skb = __skb_dequeue(list)) != NULL)
2436 void skb_rbtree_purge(struct rb_root *root);
2438 void *netdev_alloc_frag(unsigned int fragsz);
2440 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2444 * netdev_alloc_skb - allocate an skbuff for rx on a specific device
2445 * @dev: network device to receive on
2446 * @length: length to allocate
2448 * Allocate a new &sk_buff and assign it a usage count of one. The
2449 * buffer has unspecified headroom built in. Users should allocate
2450 * the headroom they think they need without accounting for the
2451 * built in space. The built in space is used for optimisations.
2453 * %NULL is returned if there is no free memory. Although this function
2454 * allocates memory it can be called from an interrupt.
2456 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2457 unsigned int length)
2459 return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2462 /* legacy helper around __netdev_alloc_skb() */
2463 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2466 return __netdev_alloc_skb(NULL, length, gfp_mask);
2469 /* legacy helper around netdev_alloc_skb() */
2470 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2472 return netdev_alloc_skb(NULL, length);
2476 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2477 unsigned int length, gfp_t gfp)
2479 struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2481 if (NET_IP_ALIGN && skb)
2482 skb_reserve(skb, NET_IP_ALIGN);
2486 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2487 unsigned int length)
2489 return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2492 static inline void skb_free_frag(void *addr)
2494 page_frag_free(addr);
2497 void *napi_alloc_frag(unsigned int fragsz);
2498 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi,
2499 unsigned int length, gfp_t gfp_mask);
2500 static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
2501 unsigned int length)
2503 return __napi_alloc_skb(napi, length, GFP_ATOMIC);
2505 void napi_consume_skb(struct sk_buff *skb, int budget);
2507 void __kfree_skb_flush(void);
2508 void __kfree_skb_defer(struct sk_buff *skb);
2511 * __dev_alloc_pages - allocate page for network Rx
2512 * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2513 * @order: size of the allocation
2515 * Allocate a new page.
2517 * %NULL is returned if there is no free memory.
2519 static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
2522 /* This piece of code contains several assumptions.
2523 * 1. This is for device Rx, therefor a cold page is preferred.
2524 * 2. The expectation is the user wants a compound page.
2525 * 3. If requesting a order 0 page it will not be compound
2526 * due to the check to see if order has a value in prep_new_page
2527 * 4. __GFP_MEMALLOC is ignored if __GFP_NOMEMALLOC is set due to
2528 * code in gfp_to_alloc_flags that should be enforcing this.
2530 gfp_mask |= __GFP_COLD | __GFP_COMP | __GFP_MEMALLOC;
2532 return alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2535 static inline struct page *dev_alloc_pages(unsigned int order)
2537 return __dev_alloc_pages(GFP_ATOMIC | __GFP_NOWARN, order);
2541 * __dev_alloc_page - allocate a page for network Rx
2542 * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2544 * Allocate a new page.
2546 * %NULL is returned if there is no free memory.
2548 static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
2550 return __dev_alloc_pages(gfp_mask, 0);
2553 static inline struct page *dev_alloc_page(void)
2555 return dev_alloc_pages(0);
2559 * skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2560 * @page: The page that was allocated from skb_alloc_page
2561 * @skb: The skb that may need pfmemalloc set
2563 static inline void skb_propagate_pfmemalloc(struct page *page,
2564 struct sk_buff *skb)
2566 if (page_is_pfmemalloc(page))
2567 skb->pfmemalloc = true;
2571 * skb_frag_page - retrieve the page referred to by a paged fragment
2572 * @frag: the paged fragment
2574 * Returns the &struct page associated with @frag.
2576 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2578 return frag->page.p;
2582 * __skb_frag_ref - take an addition reference on a paged fragment.
2583 * @frag: the paged fragment
2585 * Takes an additional reference on the paged fragment @frag.
2587 static inline void __skb_frag_ref(skb_frag_t *frag)
2589 get_page(skb_frag_page(frag));
2593 * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2595 * @f: the fragment offset.
2597 * Takes an additional reference on the @f'th paged fragment of @skb.
2599 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2601 __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2605 * __skb_frag_unref - release a reference on a paged fragment.
2606 * @frag: the paged fragment
2608 * Releases a reference on the paged fragment @frag.
2610 static inline void __skb_frag_unref(skb_frag_t *frag)
2612 put_page(skb_frag_page(frag));
2616 * skb_frag_unref - release a reference on a paged fragment of an skb.
2618 * @f: the fragment offset
2620 * Releases a reference on the @f'th paged fragment of @skb.
2622 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2624 __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2628 * skb_frag_address - gets the address of the data contained in a paged fragment
2629 * @frag: the paged fragment buffer
2631 * Returns the address of the data within @frag. The page must already
2634 static inline void *skb_frag_address(const skb_frag_t *frag)
2636 return page_address(skb_frag_page(frag)) + frag->page_offset;
2640 * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2641 * @frag: the paged fragment buffer
2643 * Returns the address of the data within @frag. Checks that the page
2644 * is mapped and returns %NULL otherwise.
2646 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2648 void *ptr = page_address(skb_frag_page(frag));
2652 return ptr + frag->page_offset;
2656 * __skb_frag_set_page - sets the page contained in a paged fragment
2657 * @frag: the paged fragment
2658 * @page: the page to set
2660 * Sets the fragment @frag to contain @page.
2662 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2664 frag->page.p = page;
2668 * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2670 * @f: the fragment offset
2671 * @page: the page to set
2673 * Sets the @f'th fragment of @skb to contain @page.
2675 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2678 __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2681 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2684 * skb_frag_dma_map - maps a paged fragment via the DMA API
2685 * @dev: the device to map the fragment to
2686 * @frag: the paged fragment to map
2687 * @offset: the offset within the fragment (starting at the
2688 * fragment's own offset)
2689 * @size: the number of bytes to map
2690 * @dir: the direction of the mapping (%PCI_DMA_*)
2692 * Maps the page associated with @frag to @device.
2694 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2695 const skb_frag_t *frag,
2696 size_t offset, size_t size,
2697 enum dma_data_direction dir)
2699 return dma_map_page(dev, skb_frag_page(frag),
2700 frag->page_offset + offset, size, dir);
2703 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2706 return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2710 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2713 return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2718 * skb_clone_writable - is the header of a clone writable
2719 * @skb: buffer to check
2720 * @len: length up to which to write
2722 * Returns true if modifying the header part of the cloned buffer
2723 * does not requires the data to be copied.
2725 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2727 return !skb_header_cloned(skb) &&
2728 skb_headroom(skb) + len <= skb->hdr_len;
2731 static inline int skb_try_make_writable(struct sk_buff *skb,
2732 unsigned int write_len)
2734 return skb_cloned(skb) && !skb_clone_writable(skb, write_len) &&
2735 pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
2738 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2743 if (headroom > skb_headroom(skb))
2744 delta = headroom - skb_headroom(skb);
2746 if (delta || cloned)
2747 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2753 * skb_cow - copy header of skb when it is required
2754 * @skb: buffer to cow
2755 * @headroom: needed headroom
2757 * If the skb passed lacks sufficient headroom or its data part
2758 * is shared, data is reallocated. If reallocation fails, an error
2759 * is returned and original skb is not changed.
2761 * The result is skb with writable area skb->head...skb->tail
2762 * and at least @headroom of space at head.
2764 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2766 return __skb_cow(skb, headroom, skb_cloned(skb));
2770 * skb_cow_head - skb_cow but only making the head writable
2771 * @skb: buffer to cow
2772 * @headroom: needed headroom
2774 * This function is identical to skb_cow except that we replace the
2775 * skb_cloned check by skb_header_cloned. It should be used when
2776 * you only need to push on some header and do not need to modify
2779 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2781 return __skb_cow(skb, headroom, skb_header_cloned(skb));
2785 * skb_padto - pad an skbuff up to a minimal size
2786 * @skb: buffer to pad
2787 * @len: minimal length
2789 * Pads up a buffer to ensure the trailing bytes exist and are
2790 * blanked. If the buffer already contains sufficient data it
2791 * is untouched. Otherwise it is extended. Returns zero on
2792 * success. The skb is freed on error.
2794 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2796 unsigned int size = skb->len;
2797 if (likely(size >= len))
2799 return skb_pad(skb, len - size);
2803 * skb_put_padto - increase size and pad an skbuff up to a minimal size
2804 * @skb: buffer to pad
2805 * @len: minimal length
2807 * Pads up a buffer to ensure the trailing bytes exist and are
2808 * blanked. If the buffer already contains sufficient data it
2809 * is untouched. Otherwise it is extended. Returns zero on
2810 * success. The skb is freed on error.
2812 static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
2814 unsigned int size = skb->len;
2816 if (unlikely(size < len)) {
2818 if (skb_pad(skb, len))
2820 __skb_put(skb, len);
2825 static inline int skb_add_data(struct sk_buff *skb,
2826 struct iov_iter *from, int copy)
2828 const int off = skb->len;
2830 if (skb->ip_summed == CHECKSUM_NONE) {
2832 if (csum_and_copy_from_iter_full(skb_put(skb, copy), copy,
2834 skb->csum = csum_block_add(skb->csum, csum, off);
2837 } else if (copy_from_iter_full(skb_put(skb, copy), copy, from))
2840 __skb_trim(skb, off);
2844 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2845 const struct page *page, int off)
2848 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2850 return page == skb_frag_page(frag) &&
2851 off == frag->page_offset + skb_frag_size(frag);
2856 static inline int __skb_linearize(struct sk_buff *skb)
2858 return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2862 * skb_linearize - convert paged skb to linear one
2863 * @skb: buffer to linarize
2865 * If there is no free memory -ENOMEM is returned, otherwise zero
2866 * is returned and the old skb data released.
2868 static inline int skb_linearize(struct sk_buff *skb)
2870 return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2874 * skb_has_shared_frag - can any frag be overwritten
2875 * @skb: buffer to test
2877 * Return true if the skb has at least one frag that might be modified
2878 * by an external entity (as in vmsplice()/sendfile())
2880 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2882 return skb_is_nonlinear(skb) &&
2883 skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2887 * skb_linearize_cow - make sure skb is linear and writable
2888 * @skb: buffer to process
2890 * If there is no free memory -ENOMEM is returned, otherwise zero
2891 * is returned and the old skb data released.
2893 static inline int skb_linearize_cow(struct sk_buff *skb)
2895 return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2896 __skb_linearize(skb) : 0;
2899 static __always_inline void
2900 __skb_postpull_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
2903 if (skb->ip_summed == CHECKSUM_COMPLETE)
2904 skb->csum = csum_block_sub(skb->csum,
2905 csum_partial(start, len, 0), off);
2906 else if (skb->ip_summed == CHECKSUM_PARTIAL &&
2907 skb_checksum_start_offset(skb) < 0)
2908 skb->ip_summed = CHECKSUM_NONE;
2912 * skb_postpull_rcsum - update checksum for received skb after pull
2913 * @skb: buffer to update
2914 * @start: start of data before pull
2915 * @len: length of data pulled
2917 * After doing a pull on a received packet, you need to call this to
2918 * update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2919 * CHECKSUM_NONE so that it can be recomputed from scratch.
2921 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2922 const void *start, unsigned int len)
2924 __skb_postpull_rcsum(skb, start, len, 0);
2927 static __always_inline void
2928 __skb_postpush_rcsum(struct sk_buff *skb, const void *start, unsigned int len,
2931 if (skb->ip_summed == CHECKSUM_COMPLETE)
2932 skb->csum = csum_block_add(skb->csum,
2933 csum_partial(start, len, 0), off);
2937 * skb_postpush_rcsum - update checksum for received skb after push
2938 * @skb: buffer to update
2939 * @start: start of data after push
2940 * @len: length of data pushed
2942 * After doing a push on a received packet, you need to call this to
2943 * update the CHECKSUM_COMPLETE checksum.
2945 static inline void skb_postpush_rcsum(struct sk_buff *skb,
2946 const void *start, unsigned int len)
2948 __skb_postpush_rcsum(skb, start, len, 0);
2951 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2954 * skb_push_rcsum - push skb and update receive checksum
2955 * @skb: buffer to update
2956 * @len: length of data pulled
2958 * This function performs an skb_push on the packet and updates
2959 * the CHECKSUM_COMPLETE checksum. It should be used on
2960 * receive path processing instead of skb_push unless you know
2961 * that the checksum difference is zero (e.g., a valid IP header)
2962 * or you are setting ip_summed to CHECKSUM_NONE.
2964 static inline unsigned char *skb_push_rcsum(struct sk_buff *skb,
2968 skb_postpush_rcsum(skb, skb->data, len);
2973 * pskb_trim_rcsum - trim received skb and update checksum
2974 * @skb: buffer to trim
2977 * This is exactly the same as pskb_trim except that it ensures the
2978 * checksum of received packets are still valid after the operation.
2981 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2983 if (likely(len >= skb->len))
2985 if (skb->ip_summed == CHECKSUM_COMPLETE)
2986 skb->ip_summed = CHECKSUM_NONE;
2987 return __pskb_trim(skb, len);
2990 static inline int __skb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2992 if (skb->ip_summed == CHECKSUM_COMPLETE)
2993 skb->ip_summed = CHECKSUM_NONE;
2994 __skb_trim(skb, len);
2998 static inline int __skb_grow_rcsum(struct sk_buff *skb, unsigned int len)
3000 if (skb->ip_summed == CHECKSUM_COMPLETE)
3001 skb->ip_summed = CHECKSUM_NONE;
3002 return __skb_grow(skb, len);
3005 #define skb_queue_walk(queue, skb) \
3006 for (skb = (queue)->next; \
3007 skb != (struct sk_buff *)(queue); \
3010 #define skb_queue_walk_safe(queue, skb, tmp) \
3011 for (skb = (queue)->next, tmp = skb->next; \
3012 skb != (struct sk_buff *)(queue); \
3013 skb = tmp, tmp = skb->next)
3015 #define skb_queue_walk_from(queue, skb) \
3016 for (; skb != (struct sk_buff *)(queue); \
3019 #define skb_queue_walk_from_safe(queue, skb, tmp) \
3020 for (tmp = skb->next; \
3021 skb != (struct sk_buff *)(queue); \
3022 skb = tmp, tmp = skb->next)
3024 #define skb_queue_reverse_walk(queue, skb) \
3025 for (skb = (queue)->prev; \
3026 skb != (struct sk_buff *)(queue); \
3029 #define skb_queue_reverse_walk_safe(queue, skb, tmp) \
3030 for (skb = (queue)->prev, tmp = skb->prev; \
3031 skb != (struct sk_buff *)(queue); \
3032 skb = tmp, tmp = skb->prev)
3034 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp) \
3035 for (tmp = skb->prev; \
3036 skb != (struct sk_buff *)(queue); \
3037 skb = tmp, tmp = skb->prev)
3039 static inline bool skb_has_frag_list(const struct sk_buff *skb)
3041 return skb_shinfo(skb)->frag_list != NULL;
3044 static inline void skb_frag_list_init(struct sk_buff *skb)
3046 skb_shinfo(skb)->frag_list = NULL;
3049 #define skb_walk_frags(skb, iter) \
3050 for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
3053 int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
3054 const struct sk_buff *skb);
3055 struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned flags,
3056 void (*destructor)(struct sock *sk,
3057 struct sk_buff *skb),
3058 int *peeked, int *off, int *err,
3059 struct sk_buff **last);
3060 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
3061 void (*destructor)(struct sock *sk,
3062 struct sk_buff *skb),
3063 int *peeked, int *off, int *err);
3064 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
3066 unsigned int datagram_poll(struct file *file, struct socket *sock,
3067 struct poll_table_struct *wait);
3068 int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
3069 struct iov_iter *to, int size);
3070 static inline int skb_copy_datagram_msg(const struct sk_buff *from, int offset,
3071 struct msghdr *msg, int size)
3073 return skb_copy_datagram_iter(from, offset, &msg->msg_iter, size);
3075 int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
3076 struct msghdr *msg);
3077 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
3078 struct iov_iter *from, int len);
3079 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
3080 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
3081 void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len);
3082 static inline void skb_free_datagram_locked(struct sock *sk,
3083 struct sk_buff *skb)
3085 __skb_free_datagram_locked(sk, skb, 0);
3087 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
3088 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
3089 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
3090 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
3091 int len, __wsum csum);
3092 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
3093 struct pipe_inode_info *pipe, unsigned int len,
3094 unsigned int flags);
3095 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
3096 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
3097 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
3099 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
3100 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
3101 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
3102 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
3103 bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu);
3104 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
3105 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
3106 int skb_ensure_writable(struct sk_buff *skb, int write_len);
3107 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci);
3108 int skb_vlan_pop(struct sk_buff *skb);
3109 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
3110 struct sk_buff *pskb_extract(struct sk_buff *skb, int off, int to_copy,
3113 static inline int memcpy_from_msg(void *data, struct msghdr *msg, int len)
3115 return copy_from_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
3118 static inline int memcpy_to_msg(struct msghdr *msg, void *data, int len)
3120 return copy_to_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
3123 struct skb_checksum_ops {
3124 __wsum (*update)(const void *mem, int len, __wsum wsum);
3125 __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
3128 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
3129 __wsum csum, const struct skb_checksum_ops *ops);
3130 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
3133 static inline void * __must_check
3134 __skb_header_pointer(const struct sk_buff *skb, int offset,
3135 int len, void *data, int hlen, void *buffer)
3137 if (hlen - offset >= len)
3138 return data + offset;
3141 skb_copy_bits(skb, offset, buffer, len) < 0)
3147 static inline void * __must_check
3148 skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer)
3150 return __skb_header_pointer(skb, offset, len, skb->data,
3151 skb_headlen(skb), buffer);
3155 * skb_needs_linearize - check if we need to linearize a given skb
3156 * depending on the given device features.
3157 * @skb: socket buffer to check
3158 * @features: net device features
3160 * Returns true if either:
3161 * 1. skb has frag_list and the device doesn't support FRAGLIST, or
3162 * 2. skb is fragmented and the device does not support SG.
3164 static inline bool skb_needs_linearize(struct sk_buff *skb,
3165 netdev_features_t features)
3167 return skb_is_nonlinear(skb) &&
3168 ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
3169 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
3172 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
3174 const unsigned int len)
3176 memcpy(to, skb->data, len);
3179 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
3180 const int offset, void *to,
3181 const unsigned int len)
3183 memcpy(to, skb->data + offset, len);
3186 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
3188 const unsigned int len)
3190 memcpy(skb->data, from, len);
3193 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
3196 const unsigned int len)
3198 memcpy(skb->data + offset, from, len);
3201 void skb_init(void);
3203 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
3209 * skb_get_timestamp - get timestamp from a skb
3210 * @skb: skb to get stamp from
3211 * @stamp: pointer to struct timeval to store stamp in
3213 * Timestamps are stored in the skb as offsets to a base timestamp.
3214 * This function converts the offset back to a struct timeval and stores
3217 static inline void skb_get_timestamp(const struct sk_buff *skb,
3218 struct timeval *stamp)
3220 *stamp = ktime_to_timeval(skb->tstamp);
3223 static inline void skb_get_timestampns(const struct sk_buff *skb,
3224 struct timespec *stamp)
3226 *stamp = ktime_to_timespec(skb->tstamp);
3229 static inline void __net_timestamp(struct sk_buff *skb)
3231 skb->tstamp = ktime_get_real();
3234 static inline ktime_t net_timedelta(ktime_t t)
3236 return ktime_sub(ktime_get_real(), t);
3239 static inline ktime_t net_invalid_timestamp(void)
3244 struct sk_buff *skb_clone_sk(struct sk_buff *skb);
3246 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
3248 void skb_clone_tx_timestamp(struct sk_buff *skb);
3249 bool skb_defer_rx_timestamp(struct sk_buff *skb);
3251 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
3253 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
3257 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
3262 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
3265 * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
3267 * PHY drivers may accept clones of transmitted packets for
3268 * timestamping via their phy_driver.txtstamp method. These drivers
3269 * must call this function to return the skb back to the stack with a
3272 * @skb: clone of the the original outgoing packet
3273 * @hwtstamps: hardware time stamps
3276 void skb_complete_tx_timestamp(struct sk_buff *skb,
3277 struct skb_shared_hwtstamps *hwtstamps);
3279 void __skb_tstamp_tx(struct sk_buff *orig_skb,
3280 struct skb_shared_hwtstamps *hwtstamps,
3281 struct sock *sk, int tstype);
3284 * skb_tstamp_tx - queue clone of skb with send time stamps
3285 * @orig_skb: the original outgoing packet
3286 * @hwtstamps: hardware time stamps, may be NULL if not available
3288 * If the skb has a socket associated, then this function clones the
3289 * skb (thus sharing the actual data and optional structures), stores
3290 * the optional hardware time stamping information (if non NULL) or
3291 * generates a software time stamp (otherwise), then queues the clone
3292 * to the error queue of the socket. Errors are silently ignored.
3294 void skb_tstamp_tx(struct sk_buff *orig_skb,
3295 struct skb_shared_hwtstamps *hwtstamps);
3297 static inline void sw_tx_timestamp(struct sk_buff *skb)
3299 if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
3300 !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
3301 skb_tstamp_tx(skb, NULL);
3305 * skb_tx_timestamp() - Driver hook for transmit timestamping
3307 * Ethernet MAC Drivers should call this function in their hard_xmit()
3308 * function immediately before giving the sk_buff to the MAC hardware.
3310 * Specifically, one should make absolutely sure that this function is
3311 * called before TX completion of this packet can trigger. Otherwise
3312 * the packet could potentially already be freed.
3314 * @skb: A socket buffer.
3316 static inline void skb_tx_timestamp(struct sk_buff *skb)
3318 skb_clone_tx_timestamp(skb);
3319 sw_tx_timestamp(skb);
3323 * skb_complete_wifi_ack - deliver skb with wifi status
3325 * @skb: the original outgoing packet
3326 * @acked: ack status
3329 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
3331 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
3332 __sum16 __skb_checksum_complete(struct sk_buff *skb);
3334 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
3336 return ((skb->ip_summed == CHECKSUM_UNNECESSARY) ||
3338 (skb->ip_summed == CHECKSUM_PARTIAL &&
3339 skb_checksum_start_offset(skb) >= 0));
3343 * skb_checksum_complete - Calculate checksum of an entire packet
3344 * @skb: packet to process
3346 * This function calculates the checksum over the entire packet plus
3347 * the value of skb->csum. The latter can be used to supply the
3348 * checksum of a pseudo header as used by TCP/UDP. It returns the
3351 * For protocols that contain complete checksums such as ICMP/TCP/UDP,
3352 * this function can be used to verify that checksum on received
3353 * packets. In that case the function should return zero if the
3354 * checksum is correct. In particular, this function will return zero
3355 * if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
3356 * hardware has already verified the correctness of the checksum.
3358 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
3360 return skb_csum_unnecessary(skb) ?
3361 0 : __skb_checksum_complete(skb);
3364 static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
3366 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3367 if (skb->csum_level == 0)
3368 skb->ip_summed = CHECKSUM_NONE;
3374 static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
3376 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3377 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
3379 } else if (skb->ip_summed == CHECKSUM_NONE) {
3380 skb->ip_summed = CHECKSUM_UNNECESSARY;
3381 skb->csum_level = 0;
3385 static inline void __skb_mark_checksum_bad(struct sk_buff *skb)
3387 /* Mark current checksum as bad (typically called from GRO
3388 * path). In the case that ip_summed is CHECKSUM_NONE
3389 * this must be the first checksum encountered in the packet.
3390 * When ip_summed is CHECKSUM_UNNECESSARY, this is the first
3391 * checksum after the last one validated. For UDP, a zero
3392 * checksum can not be marked as bad.
3395 if (skb->ip_summed == CHECKSUM_NONE ||
3396 skb->ip_summed == CHECKSUM_UNNECESSARY)
3400 /* Check if we need to perform checksum complete validation.
3402 * Returns true if checksum complete is needed, false otherwise
3403 * (either checksum is unnecessary or zero checksum is allowed).
3405 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
3409 if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
3410 skb->csum_valid = 1;
3411 __skb_decr_checksum_unnecessary(skb);
3418 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
3421 #define CHECKSUM_BREAK 76
3423 /* Unset checksum-complete
3425 * Unset checksum complete can be done when packet is being modified
3426 * (uncompressed for instance) and checksum-complete value is
3429 static inline void skb_checksum_complete_unset(struct sk_buff *skb)
3431 if (skb->ip_summed == CHECKSUM_COMPLETE)
3432 skb->ip_summed = CHECKSUM_NONE;
3435 /* Validate (init) checksum based on checksum complete.
3438 * 0: checksum is validated or try to in skb_checksum_complete. In the latter
3439 * case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
3440 * checksum is stored in skb->csum for use in __skb_checksum_complete
3441 * non-zero: value of invalid checksum
3444 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
3448 if (skb->ip_summed == CHECKSUM_COMPLETE) {
3449 if (!csum_fold(csum_add(psum, skb->csum))) {
3450 skb->csum_valid = 1;
3453 } else if (skb->csum_bad) {
3454 /* ip_summed == CHECKSUM_NONE in this case */
3455 return (__force __sum16)1;
3460 if (complete || skb->len <= CHECKSUM_BREAK) {
3463 csum = __skb_checksum_complete(skb);
3464 skb->csum_valid = !csum;
3471 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
3476 /* Perform checksum validate (init). Note that this is a macro since we only
3477 * want to calculate the pseudo header which is an input function if necessary.
3478 * First we try to validate without any computation (checksum unnecessary) and
3479 * then calculate based on checksum complete calling the function to compute
3483 * 0: checksum is validated or try to in skb_checksum_complete
3484 * non-zero: value of invalid checksum
3486 #define __skb_checksum_validate(skb, proto, complete, \
3487 zero_okay, check, compute_pseudo) \
3489 __sum16 __ret = 0; \
3490 skb->csum_valid = 0; \
3491 if (__skb_checksum_validate_needed(skb, zero_okay, check)) \
3492 __ret = __skb_checksum_validate_complete(skb, \
3493 complete, compute_pseudo(skb, proto)); \
3497 #define skb_checksum_init(skb, proto, compute_pseudo) \
3498 __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
3500 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
3501 __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
3503 #define skb_checksum_validate(skb, proto, compute_pseudo) \
3504 __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
3506 #define skb_checksum_validate_zero_check(skb, proto, check, \
3508 __skb_checksum_validate(skb, proto, true, true, check, compute_pseudo)
3510 #define skb_checksum_simple_validate(skb) \
3511 __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
3513 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
3515 return (skb->ip_summed == CHECKSUM_NONE &&
3516 skb->csum_valid && !skb->csum_bad);
3519 static inline void __skb_checksum_convert(struct sk_buff *skb,
3520 __sum16 check, __wsum pseudo)
3522 skb->csum = ~pseudo;
3523 skb->ip_summed = CHECKSUM_COMPLETE;
3526 #define skb_checksum_try_convert(skb, proto, check, compute_pseudo) \
3528 if (__skb_checksum_convert_check(skb)) \
3529 __skb_checksum_convert(skb, check, \
3530 compute_pseudo(skb, proto)); \
3533 static inline void skb_remcsum_adjust_partial(struct sk_buff *skb, void *ptr,
3534 u16 start, u16 offset)
3536 skb->ip_summed = CHECKSUM_PARTIAL;
3537 skb->csum_start = ((unsigned char *)ptr + start) - skb->head;
3538 skb->csum_offset = offset - start;
3541 /* Update skbuf and packet to reflect the remote checksum offload operation.
3542 * When called, ptr indicates the starting point for skb->csum when
3543 * ip_summed is CHECKSUM_COMPLETE. If we need create checksum complete
3544 * here, skb_postpull_rcsum is done so skb->csum start is ptr.
3546 static inline void skb_remcsum_process(struct sk_buff *skb, void *ptr,
3547 int start, int offset, bool nopartial)
3552 skb_remcsum_adjust_partial(skb, ptr, start, offset);
3556 if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
3557 __skb_checksum_complete(skb);
3558 skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);
3561 delta = remcsum_adjust(ptr, skb->csum, start, offset);
3563 /* Adjust skb->csum since we changed the packet */
3564 skb->csum = csum_add(skb->csum, delta);
3567 static inline struct nf_conntrack *skb_nfct(const struct sk_buff *skb)
3569 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
3570 return (void *)(skb->_nfct & SKB_NFCT_PTRMASK);
3576 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3577 void nf_conntrack_destroy(struct nf_conntrack *nfct);
3578 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
3580 if (nfct && atomic_dec_and_test(&nfct->use))
3581 nf_conntrack_destroy(nfct);
3583 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
3586 atomic_inc(&nfct->use);
3589 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3590 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
3592 if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
3595 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
3598 atomic_inc(&nf_bridge->use);
3600 #endif /* CONFIG_BRIDGE_NETFILTER */
3601 static inline void nf_reset(struct sk_buff *skb)
3603 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3604 nf_conntrack_put(skb_nfct(skb));
3607 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3608 nf_bridge_put(skb->nf_bridge);
3609 skb->nf_bridge = NULL;
3613 static inline void nf_reset_trace(struct sk_buff *skb)
3615 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3620 /* Note: This doesn't put any conntrack and bridge info in dst. */
3621 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
3624 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3625 dst->_nfct = src->_nfct;
3626 nf_conntrack_get(skb_nfct(src));
3628 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3629 dst->nf_bridge = src->nf_bridge;
3630 nf_bridge_get(src->nf_bridge);
3632 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3634 dst->nf_trace = src->nf_trace;
3638 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
3640 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3641 nf_conntrack_put(skb_nfct(dst));
3643 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3644 nf_bridge_put(dst->nf_bridge);
3646 __nf_copy(dst, src, true);
3649 #ifdef CONFIG_NETWORK_SECMARK
3650 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3652 to->secmark = from->secmark;
3655 static inline void skb_init_secmark(struct sk_buff *skb)
3660 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3663 static inline void skb_init_secmark(struct sk_buff *skb)
3667 static inline bool skb_irq_freeable(const struct sk_buff *skb)
3669 return !skb->destructor &&
3670 #if IS_ENABLED(CONFIG_XFRM)
3674 !skb->_skb_refdst &&
3675 !skb_has_frag_list(skb);
3678 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
3680 skb->queue_mapping = queue_mapping;
3683 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
3685 return skb->queue_mapping;
3688 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
3690 to->queue_mapping = from->queue_mapping;
3693 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
3695 skb->queue_mapping = rx_queue + 1;
3698 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
3700 return skb->queue_mapping - 1;
3703 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3705 return skb->queue_mapping != 0;
3708 static inline void skb_set_dst_pending_confirm(struct sk_buff *skb, u32 val)
3710 skb->dst_pending_confirm = val;
3713 static inline bool skb_get_dst_pending_confirm(const struct sk_buff *skb)
3715 return skb->dst_pending_confirm != 0;
3718 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3727 /* Keeps track of mac header offset relative to skb->head.
3728 * It is useful for TSO of Tunneling protocol. e.g. GRE.
3729 * For non-tunnel skb it points to skb_mac_header() and for
3730 * tunnel skb it points to outer mac header.
3731 * Keeps track of level of encapsulation of network headers.
3742 #define SKB_SGO_CB_OFFSET 32
3743 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_SGO_CB_OFFSET))
3745 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3747 return (skb_mac_header(inner_skb) - inner_skb->head) -
3748 SKB_GSO_CB(inner_skb)->mac_offset;
3751 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3753 int new_headroom, headroom;
3756 headroom = skb_headroom(skb);
3757 ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3761 new_headroom = skb_headroom(skb);
3762 SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3766 static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res)
3768 /* Do not update partial checksums if remote checksum is enabled. */
3769 if (skb->remcsum_offload)
3772 SKB_GSO_CB(skb)->csum = res;
3773 SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head;
3776 /* Compute the checksum for a gso segment. First compute the checksum value
3777 * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
3778 * then add in skb->csum (checksum from csum_start to end of packet).
3779 * skb->csum and csum_start are then updated to reflect the checksum of the
3780 * resultant packet starting from the transport header-- the resultant checksum
3781 * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
3784 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
3786 unsigned char *csum_start = skb_transport_header(skb);
3787 int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;
3788 __wsum partial = SKB_GSO_CB(skb)->csum;
3790 SKB_GSO_CB(skb)->csum = res;
3791 SKB_GSO_CB(skb)->csum_start = csum_start - skb->head;
3793 return csum_fold(csum_partial(csum_start, plen, partial));
3796 static inline bool skb_is_gso(const struct sk_buff *skb)
3798 return skb_shinfo(skb)->gso_size;
3801 /* Note: Should be called only if skb_is_gso(skb) is true */
3802 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
3804 return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
3807 static inline void skb_gso_reset(struct sk_buff *skb)
3809 skb_shinfo(skb)->gso_size = 0;
3810 skb_shinfo(skb)->gso_segs = 0;
3811 skb_shinfo(skb)->gso_type = 0;
3814 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
3816 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
3818 /* LRO sets gso_size but not gso_type, whereas if GSO is really
3819 * wanted then gso_type will be set. */
3820 const struct skb_shared_info *shinfo = skb_shinfo(skb);
3822 if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
3823 unlikely(shinfo->gso_type == 0)) {
3824 __skb_warn_lro_forwarding(skb);
3830 static inline void skb_forward_csum(struct sk_buff *skb)
3832 /* Unfortunately we don't support this one. Any brave souls? */
3833 if (skb->ip_summed == CHECKSUM_COMPLETE)
3834 skb->ip_summed = CHECKSUM_NONE;
3838 * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
3839 * @skb: skb to check
3841 * fresh skbs have their ip_summed set to CHECKSUM_NONE.
3842 * Instead of forcing ip_summed to CHECKSUM_NONE, we can
3843 * use this helper, to document places where we make this assertion.
3845 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
3848 BUG_ON(skb->ip_summed != CHECKSUM_NONE);
3852 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
3854 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
3855 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
3856 unsigned int transport_len,
3857 __sum16(*skb_chkf)(struct sk_buff *skb));
3860 * skb_head_is_locked - Determine if the skb->head is locked down
3861 * @skb: skb to check
3863 * The head on skbs build around a head frag can be removed if they are
3864 * not cloned. This function returns true if the skb head is locked down
3865 * due to either being allocated via kmalloc, or by being a clone with
3866 * multiple references to the head.
3868 static inline bool skb_head_is_locked(const struct sk_buff *skb)
3870 return !skb->head_frag || skb_cloned(skb);
3874 * skb_gso_network_seglen - Return length of individual segments of a gso packet
3878 * skb_gso_network_seglen is used to determine the real size of the
3879 * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
3881 * The MAC/L2 header is not accounted for.
3883 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
3885 unsigned int hdr_len = skb_transport_header(skb) -
3886 skb_network_header(skb);
3887 return hdr_len + skb_gso_transport_seglen(skb);
3890 /* Local Checksum Offload.
3891 * Compute outer checksum based on the assumption that the
3892 * inner checksum will be offloaded later.
3893 * See Documentation/networking/checksum-offloads.txt for
3894 * explanation of how this works.
3895 * Fill in outer checksum adjustment (e.g. with sum of outer
3896 * pseudo-header) before calling.
3897 * Also ensure that inner checksum is in linear data area.
3899 static inline __wsum lco_csum(struct sk_buff *skb)
3901 unsigned char *csum_start = skb_checksum_start(skb);
3902 unsigned char *l4_hdr = skb_transport_header(skb);
3905 /* Start with complement of inner checksum adjustment */
3906 partial = ~csum_unfold(*(__force __sum16 *)(csum_start +
3909 /* Add in checksum of our headers (incl. outer checksum
3910 * adjustment filled in by caller) and return result.
3912 return csum_partial(l4_hdr, csum_start - l4_hdr, partial);
3915 #endif /* __KERNEL__ */
3916 #endif /* _LINUX_SKBUFF_H */