net/core/gro.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 #include <net/gro.h>
   3 #include <net/dst_metadata.h>
   4 #include <net/busy_poll.h>
   5 #include <trace/events/net.h>
   6
   7 #define MAX_GRO_SKBS 8
   8
   9 /* This should be increased if a protocol with a bigger head is added. */
  10 #define GRO_MAX_HEAD (MAX_HEADER + 128)
  11
  12 static DEFINE_SPINLOCK(offload_lock);
  13 static struct list_head offload_base __read_mostly = LIST_HEAD_INIT(offload_base);
  14 /* Maximum number of GRO_NORMAL skbs to batch up for list-RX */
  15 int gro_normal_batch __read_mostly = 8;
  16
  17 /**
  18  *      dev_add_offload - register offload handlers
  19  *      @po: protocol offload declaration
  20  *
  21  *      Add protocol offload handlers to the networking stack. The passed
  22  *      &proto_offload is linked into kernel lists and may not be freed until
  23  *      it has been removed from the kernel lists.
  24  *
  25  *      This call does not sleep therefore it can not
  26  *      guarantee all CPU's that are in middle of receiving packets
  27  *      will see the new offload handlers (until the next received packet).
  28  */
  29 void dev_add_offload(struct packet_offload *po)
  30 {
  31         struct packet_offload *elem;
  32
  33         spin_lock(&offload_lock);
  34         list_for_each_entry(elem, &offload_base, list) {
  35                 if (po->priority < elem->priority)
  36                         break;
  37         }
  38         list_add_rcu(&po->list, elem->list.prev);
  39         spin_unlock(&offload_lock);
  40 }
  41 EXPORT_SYMBOL(dev_add_offload);
  42
  43 /**
  44  *      __dev_remove_offload     - remove offload handler
  45  *      @po: packet offload declaration
  46  *
  47  *      Remove a protocol offload handler that was previously added to the
  48  *      kernel offload handlers by dev_add_offload(). The passed &offload_type
  49  *      is removed from the kernel lists and can be freed or reused once this
  50  *      function returns.
  51  *
  52  *      The packet type might still be in use by receivers
  53  *      and must not be freed until after all the CPU's have gone
  54  *      through a quiescent state.
  55  */
  56 static void __dev_remove_offload(struct packet_offload *po)
  57 {
  58         struct list_head *head = &offload_base;
  59         struct packet_offload *po1;
  60
  61         spin_lock(&offload_lock);
  62
  63         list_for_each_entry(po1, head, list) {
  64                 if (po == po1) {
  65                         list_del_rcu(&po->list);
  66                         goto out;
  67                 }
  68         }
  69
  70         pr_warn("dev_remove_offload: %p not found\n", po);
  71 out:
  72         spin_unlock(&offload_lock);
  73 }
  74
  75 /**
  76  *      dev_remove_offload       - remove packet offload handler
  77  *      @po: packet offload declaration
  78  *
  79  *      Remove a packet offload handler that was previously added to the kernel
  80  *      offload handlers by dev_add_offload(). The passed &offload_type is
  81  *      removed from the kernel lists and can be freed or reused once this
  82  *      function returns.
  83  *
  84  *      This call sleeps to guarantee that no CPU is looking at the packet
  85  *      type after return.
  86  */
  87 void dev_remove_offload(struct packet_offload *po)
  88 {
  89         __dev_remove_offload(po);
  90
  91         synchronize_net();
  92 }
  93 EXPORT_SYMBOL(dev_remove_offload);
  94
  95 /**
  96  *      skb_eth_gso_segment - segmentation handler for ethernet protocols.
  97  *      @skb: buffer to segment
  98  *      @features: features for the output path (see dev->features)
  99  *      @type: Ethernet Protocol ID
 100  */
 101 struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb,
 102                                     netdev_features_t features, __be16 type)
 103 {
 104         struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
 105         struct packet_offload *ptype;
 106
 107         rcu_read_lock();
 108         list_for_each_entry_rcu(ptype, &offload_base, list) {
 109                 if (ptype->type == type && ptype->callbacks.gso_segment) {
 110                         segs = ptype->callbacks.gso_segment(skb, features);
 111                         break;
 112                 }
 113         }
 114         rcu_read_unlock();
 115
 116         return segs;
 117 }
 118 EXPORT_SYMBOL(skb_eth_gso_segment);
 119
 120 /**
 121  *      skb_mac_gso_segment - mac layer segmentation handler.
 122  *      @skb: buffer to segment
 123  *      @features: features for the output path (see dev->features)
 124  */
 125 struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
 126                                     netdev_features_t features)
 127 {
 128         struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
 129         struct packet_offload *ptype;
 130         int vlan_depth = skb->mac_len;
 131         __be16 type = skb_network_protocol(skb, &vlan_depth);
 132
 133         if (unlikely(!type))
 134                 return ERR_PTR(-EINVAL);
 135
 136         __skb_pull(skb, vlan_depth);
 137
 138         rcu_read_lock();
 139         list_for_each_entry_rcu(ptype, &offload_base, list) {
 140                 if (ptype->type == type && ptype->callbacks.gso_segment) {
 141                         segs = ptype->callbacks.gso_segment(skb, features);
 142                         break;
 143                 }
 144         }
 145         rcu_read_unlock();
 146
 147         __skb_push(skb, skb->data - skb_mac_header(skb));
 148
 149         return segs;
 150 }
 151 EXPORT_SYMBOL(skb_mac_gso_segment);
 152
 153 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
 154 {
 155         struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
 156         unsigned int offset = skb_gro_offset(skb);
 157         unsigned int headlen = skb_headlen(skb);
 158         unsigned int len = skb_gro_len(skb);
 159         unsigned int delta_truesize;
 160         unsigned int gro_max_size;
 161         unsigned int new_truesize;
 162         struct sk_buff *lp;
 163
 164         /* pairs with WRITE_ONCE() in netif_set_gro_max_size() */
 165         gro_max_size = READ_ONCE(p->dev->gro_max_size);
 166
 167         if (unlikely(p->len + len >= gro_max_size || NAPI_GRO_CB(skb)->flush))
 168                 return -E2BIG;
 169
 170         if (unlikely(p->len + len >= GRO_LEGACY_MAX_SIZE)) {
 171                 if (p->protocol != htons(ETH_P_IPV6) ||
 172                     skb_headroom(p) < sizeof(struct hop_jumbo_hdr) ||
 173                     ipv6_hdr(p)->nexthdr != IPPROTO_TCP ||
 174                     p->encapsulation)
 175                         return -E2BIG;
 176         }
 177
 178         lp = NAPI_GRO_CB(p)->last;
 179         pinfo = skb_shinfo(lp);
 180
 181         if (headlen <= offset) {
 182                 skb_frag_t *frag;
 183                 skb_frag_t *frag2;
 184                 int i = skbinfo->nr_frags;
 185                 int nr_frags = pinfo->nr_frags + i;
 186
 187                 if (nr_frags > MAX_SKB_FRAGS)
 188                         goto merge;
 189
 190                 offset -= headlen;
 191                 pinfo->nr_frags = nr_frags;
 192                 skbinfo->nr_frags = 0;
 193
 194                 frag = pinfo->frags + nr_frags;
 195                 frag2 = skbinfo->frags + i;
 196                 do {
 197                         *--frag = *--frag2;
 198                 } while (--i);
 199
 200                 skb_frag_off_add(frag, offset);
 201                 skb_frag_size_sub(frag, offset);
 202
 203                 /* all fragments truesize : remove (head size + sk_buff) */
 204                 new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
 205                 delta_truesize = skb->truesize - new_truesize;
 206
 207                 skb->truesize = new_truesize;
 208                 skb->len -= skb->data_len;
 209                 skb->data_len = 0;
 210
 211                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
 212                 goto done;
 213         } else if (skb->head_frag) {
 214                 int nr_frags = pinfo->nr_frags;
 215                 skb_frag_t *frag = pinfo->frags + nr_frags;
 216                 struct page *page = virt_to_head_page(skb->head);
 217                 unsigned int first_size = headlen - offset;
 218                 unsigned int first_offset;
 219
 220                 if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
 221                         goto merge;
 222
 223                 first_offset = skb->data -
 224                                (unsigned char *)page_address(page) +
 225                                offset;
 226
 227                 pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
 228
 229                 __skb_frag_set_page(frag, page);
 230                 skb_frag_off_set(frag, first_offset);
 231                 skb_frag_size_set(frag, first_size);
 232
 233                 memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 234                 /* We dont need to clear skbinfo->nr_frags here */
 235
 236                 new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
 237                 delta_truesize = skb->truesize - new_truesize;
 238                 skb->truesize = new_truesize;
 239                 NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
 240                 goto done;
 241         }
 242
 243 merge:
 244         /* sk owenrship - if any - completely transferred to the aggregated packet */
 245         skb->destructor = NULL;
 246         delta_truesize = skb->truesize;
 247         if (offset > headlen) {
 248                 unsigned int eat = offset - headlen;
 249
 250                 skb_frag_off_add(&skbinfo->frags[0], eat);
 251                 skb_frag_size_sub(&skbinfo->frags[0], eat);
 252                 skb->data_len -= eat;
 253                 skb->len -= eat;
 254                 offset = headlen;
 255         }
 256
 257         __skb_pull(skb, offset);
 258
 259         if (NAPI_GRO_CB(p)->last == p)
 260                 skb_shinfo(p)->frag_list = skb;
 261         else
 262                 NAPI_GRO_CB(p)->last->next = skb;
 263         NAPI_GRO_CB(p)->last = skb;
 264         __skb_header_release(skb);
 265         lp = p;
 266
 267 done:
 268         NAPI_GRO_CB(p)->count++;
 269         p->data_len += len;
 270         p->truesize += delta_truesize;
 271         p->len += len;
 272         if (lp != p) {
 273                 lp->data_len += len;
 274                 lp->truesize += delta_truesize;
 275                 lp->len += len;
 276         }
 277         NAPI_GRO_CB(skb)->same_flow = 1;
 278         return 0;
 279 }
 280
 281
 282 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 283 {
 284         struct packet_offload *ptype;
 285         __be16 type = skb->protocol;
 286         struct list_head *head = &offload_base;
 287         int err = -ENOENT;
 288
 289         BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));
 290
 291         if (NAPI_GRO_CB(skb)->count == 1) {
 292                 skb_shinfo(skb)->gso_size = 0;
 293                 goto out;
 294         }
 295
 296         rcu_read_lock();
 297         list_for_each_entry_rcu(ptype, head, list) {
 298                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 299                         continue;
 300
 301                 err = INDIRECT_CALL_INET(ptype->callbacks.gro_complete,
 302                                          ipv6_gro_complete, inet_gro_complete,
 303                                          skb, 0);
 304                 break;
 305         }
 306         rcu_read_unlock();
 307
 308         if (err) {
 309                 WARN_ON(&ptype->list == head);
 310                 kfree_skb(skb);
 311                 return;
 312         }
 313
 314 out:
 315         gro_normal_one(napi, skb, NAPI_GRO_CB(skb)->count);
 316 }
 317
 318 static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
 319                                    bool flush_old)
 320 {
 321         struct list_head *head = &napi->gro_hash[index].list;
 322         struct sk_buff *skb, *p;
 323
 324         list_for_each_entry_safe_reverse(skb, p, head, list) {
 325                 if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)
 326                         return;
 327                 skb_list_del_init(skb);
 328                 napi_gro_complete(napi, skb);
 329                 napi->gro_hash[index].count--;
 330         }
 331
 332         if (!napi->gro_hash[index].count)
 333                 __clear_bit(index, &napi->gro_bitmask);
 334 }
 335
 336 /* napi->gro_hash[].list contains packets ordered by age.
 337  * youngest packets at the head of it.
 338  * Complete skbs in reverse order to reduce latencies.
 339  */
 340 void napi_gro_flush(struct napi_struct *napi, bool flush_old)
 341 {
 342         unsigned long bitmask = napi->gro_bitmask;
 343         unsigned int i, base = ~0U;
 344
 345         while ((i = ffs(bitmask)) != 0) {
 346                 bitmask >>= i;
 347                 base += i;
 348                 __napi_gro_flush_chain(napi, base, flush_old);
 349         }
 350 }
 351 EXPORT_SYMBOL(napi_gro_flush);
 352
 353 static void gro_list_prepare(const struct list_head *head,
 354                              const struct sk_buff *skb)
 355 {
 356         unsigned int maclen = skb->dev->hard_header_len;
 357         u32 hash = skb_get_hash_raw(skb);
 358         struct sk_buff *p;
 359
 360         list_for_each_entry(p, head, list) {
 361                 unsigned long diffs;
 362
 363                 NAPI_GRO_CB(p)->flush = 0;
 364
 365                 if (hash != skb_get_hash_raw(p)) {
 366                         NAPI_GRO_CB(p)->same_flow = 0;
 367                         continue;
 368                 }
 369
 370                 diffs = (unsigned long)p->dev ^ (unsigned long)skb->dev;
 371                 diffs |= skb_vlan_tag_present(p) ^ skb_vlan_tag_present(skb);
 372                 if (skb_vlan_tag_present(p))
 373                         diffs |= skb_vlan_tag_get(p) ^ skb_vlan_tag_get(skb);
 374                 diffs |= skb_metadata_differs(p, skb);
 375                 if (maclen == ETH_HLEN)
 376                         diffs |= compare_ether_header(skb_mac_header(p),
 377                                                       skb_mac_header(skb));
 378                 else if (!diffs)
 379                         diffs = memcmp(skb_mac_header(p),
 380                                        skb_mac_header(skb),
 381                                        maclen);
 382
 383                 /* in most common scenarions 'slow_gro' is 0
 384                  * otherwise we are already on some slower paths
 385                  * either skip all the infrequent tests altogether or
 386                  * avoid trying too hard to skip each of them individually
 387                  */
 388                 if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
 389 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 390                         struct tc_skb_ext *skb_ext;
 391                         struct tc_skb_ext *p_ext;
 392 #endif
 393
 394                         diffs |= p->sk != skb->sk;
 395                         diffs |= skb_metadata_dst_cmp(p, skb);
 396                         diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 397
 398 #if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 399                         skb_ext = skb_ext_find(skb, TC_SKB_EXT);
 400                         p_ext = skb_ext_find(p, TC_SKB_EXT);
 401
 402                         diffs |= (!!p_ext) ^ (!!skb_ext);
 403                         if (!diffs && unlikely(skb_ext))
 404                                 diffs |= p_ext->chain ^ skb_ext->chain;
 405 #endif
 406                 }
 407
 408                 NAPI_GRO_CB(p)->same_flow = !diffs;
 409         }
 410 }
 411
 412 static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
 413 {
 414         const struct skb_shared_info *pinfo = skb_shinfo(skb);
 415         const skb_frag_t *frag0 = &pinfo->frags[0];
 416
 417         NAPI_GRO_CB(skb)->data_offset = 0;
 418         NAPI_GRO_CB(skb)->frag0 = NULL;
 419         NAPI_GRO_CB(skb)->frag0_len = 0;
 420
 421         if (!skb_headlen(skb) && pinfo->nr_frags &&
 422             !PageHighMem(skb_frag_page(frag0)) &&
 423             (!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
 424                 NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
 425                 NAPI_GRO_CB(skb)->frag0_len = min_t(unsigned int,
 426                                                     skb_frag_size(frag0),
 427                                                     skb->end - skb->tail);
 428         }
 429 }
 430
 431 static void gro_pull_from_frag0(struct sk_buff *skb, int grow)
 432 {
 433         struct skb_shared_info *pinfo = skb_shinfo(skb);
 434
 435         BUG_ON(skb->end - skb->tail < grow);
 436
 437         memcpy(skb_tail_pointer(skb), NAPI_GRO_CB(skb)->frag0, grow);
 438
 439         skb->data_len -= grow;
 440         skb->tail += grow;
 441
 442         skb_frag_off_add(&pinfo->frags[0], grow);
 443         skb_frag_size_sub(&pinfo->frags[0], grow);
 444
 445         if (unlikely(!skb_frag_size(&pinfo->frags[0]))) {
 446                 skb_frag_unref(skb, 0);
 447                 memmove(pinfo->frags, pinfo->frags + 1,
 448                         --pinfo->nr_frags * sizeof(pinfo->frags[0]));
 449         }
 450 }
 451
 452 static void gro_flush_oldest(struct napi_struct *napi, struct list_head *head)
 453 {
 454         struct sk_buff *oldest;
 455
 456         oldest = list_last_entry(head, struct sk_buff, list);
 457
 458         /* We are called with head length >= MAX_GRO_SKBS, so this is
 459          * impossible.
 460          */
 461         if (WARN_ON_ONCE(!oldest))
 462                 return;
 463
 464         /* Do not adjust napi->gro_hash[].count, caller is adding a new
 465          * SKB to the chain.
 466          */
 467         skb_list_del_init(oldest);
 468         napi_gro_complete(napi, oldest);
 469 }
 470
 471 static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 472 {
 473         u32 bucket = skb_get_hash_raw(skb) & (GRO_HASH_BUCKETS - 1);
 474         struct gro_list *gro_list = &napi->gro_hash[bucket];
 475         struct list_head *head = &offload_base;
 476         struct packet_offload *ptype;
 477         __be16 type = skb->protocol;
 478         struct sk_buff *pp = NULL;
 479         enum gro_result ret;
 480         int same_flow;
 481         int grow;
 482
 483         if (netif_elide_gro(skb->dev))
 484                 goto normal;
 485
 486         gro_list_prepare(&gro_list->list, skb);
 487
 488         rcu_read_lock();
 489         list_for_each_entry_rcu(ptype, head, list) {
 490                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 491                         continue;
 492
 493                 skb_set_network_header(skb, skb_gro_offset(skb));
 494                 skb_reset_mac_len(skb);
 495                 BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32));
 496                 BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed),
 497                                          sizeof(u32))); /* Avoid slow unaligned acc */
 498                 *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
 499                 NAPI_GRO_CB(skb)->flush = skb_is_gso(skb) || skb_has_frag_list(skb);
 500                 NAPI_GRO_CB(skb)->is_atomic = 1;
 501
 502                 /* Setup for GRO checksum validation */
 503                 switch (skb->ip_summed) {
 504                 case CHECKSUM_COMPLETE:
 505                         NAPI_GRO_CB(skb)->csum = skb->csum;
 506                         NAPI_GRO_CB(skb)->csum_valid = 1;
 507                         break;
 508                 case CHECKSUM_UNNECESSARY:
 509                         NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
 510                         break;
 511                 }
 512
 513                 pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive,
 514                                         ipv6_gro_receive, inet_gro_receive,
 515                                         &gro_list->list, skb);
 516                 break;
 517         }
 518         rcu_read_unlock();
 519
 520         if (&ptype->list == head)
 521                 goto normal;
 522
 523         if (PTR_ERR(pp) == -EINPROGRESS) {
 524                 ret = GRO_CONSUMED;
 525                 goto ok;
 526         }
 527
 528         same_flow = NAPI_GRO_CB(skb)->same_flow;
 529         ret = NAPI_GRO_CB(skb)->free ? GRO_MERGED_FREE : GRO_MERGED;
 530
 531         if (pp) {
 532                 skb_list_del_init(pp);
 533                 napi_gro_complete(napi, pp);
 534                 gro_list->count--;
 535         }
 536
 537         if (same_flow)
 538                 goto ok;
 539
 540         if (NAPI_GRO_CB(skb)->flush)
 541                 goto normal;
 542
 543         if (unlikely(gro_list->count >= MAX_GRO_SKBS))
 544                 gro_flush_oldest(napi, &gro_list->list);
 545         else
 546                 gro_list->count++;
 547
 548         NAPI_GRO_CB(skb)->count = 1;
 549         NAPI_GRO_CB(skb)->age = jiffies;
 550         NAPI_GRO_CB(skb)->last = skb;
 551         skb_shinfo(skb)->gso_size = skb_gro_len(skb);
 552         list_add(&skb->list, &gro_list->list);
 553         ret = GRO_HELD;
 554
 555 pull:
 556         grow = skb_gro_offset(skb) - skb_headlen(skb);
 557         if (grow > 0)
 558                 gro_pull_from_frag0(skb, grow);
 559 ok:
 560         if (gro_list->count) {
 561                 if (!test_bit(bucket, &napi->gro_bitmask))
 562                         __set_bit(bucket, &napi->gro_bitmask);
 563         } else if (test_bit(bucket, &napi->gro_bitmask)) {
 564                 __clear_bit(bucket, &napi->gro_bitmask);
 565         }
 566
 567         return ret;
 568
 569 normal:
 570         ret = GRO_NORMAL;
 571         goto pull;
 572 }
 573
 574 struct packet_offload *gro_find_receive_by_type(__be16 type)
 575 {
 576         struct list_head *offload_head = &offload_base;
 577         struct packet_offload *ptype;
 578
 579         list_for_each_entry_rcu(ptype, offload_head, list) {
 580                 if (ptype->type != type || !ptype->callbacks.gro_receive)
 581                         continue;
 582                 return ptype;
 583         }
 584         return NULL;
 585 }
 586 EXPORT_SYMBOL(gro_find_receive_by_type);
 587
 588 struct packet_offload *gro_find_complete_by_type(__be16 type)
 589 {
 590         struct list_head *offload_head = &offload_base;
 591         struct packet_offload *ptype;
 592
 593         list_for_each_entry_rcu(ptype, offload_head, list) {
 594                 if (ptype->type != type || !ptype->callbacks.gro_complete)
 595                         continue;
 596                 return ptype;
 597         }
 598         return NULL;
 599 }
 600 EXPORT_SYMBOL(gro_find_complete_by_type);
 601
 602 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 603                                     struct sk_buff *skb,
 604                                     gro_result_t ret)
 605 {
 606         switch (ret) {
 607         case GRO_NORMAL:
 608                 gro_normal_one(napi, skb, 1);
 609                 break;
 610
 611         case GRO_MERGED_FREE:
 612                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 613                         napi_skb_free_stolen_head(skb);
 614                 else if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
 615                         __kfree_skb(skb);
 616                 else
 617                         __kfree_skb_defer(skb);
 618                 break;
 619
 620         case GRO_HELD:
 621         case GRO_MERGED:
 622         case GRO_CONSUMED:
 623                 break;
 624         }
 625
 626         return ret;
 627 }
 628
 629 gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
 630 {
 631         gro_result_t ret;
 632
 633         skb_mark_napi_id(skb, napi);
 634         trace_napi_gro_receive_entry(skb);
 635
 636         skb_gro_reset_offset(skb, 0);
 637
 638         ret = napi_skb_finish(napi, skb, dev_gro_receive(napi, skb));
 639         trace_napi_gro_receive_exit(ret);
 640
 641         return ret;
 642 }
 643 EXPORT_SYMBOL(napi_gro_receive);
 644
 645 static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 646 {
 647         if (unlikely(skb->pfmemalloc)) {
 648                 consume_skb(skb);
 649                 return;
 650         }
 651         __skb_pull(skb, skb_headlen(skb));
 652         /* restore the reserve we had after netdev_alloc_skb_ip_align() */
 653         skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN - skb_headroom(skb));
 654         __vlan_hwaccel_clear_tag(skb);
 655         skb->dev = napi->dev;
 656         skb->skb_iif = 0;
 657
 658         /* eth_type_trans() assumes pkt_type is PACKET_HOST */
 659         skb->pkt_type = PACKET_HOST;
 660
 661         skb->encapsulation = 0;
 662         skb_shinfo(skb)->gso_type = 0;
 663         if (unlikely(skb->slow_gro)) {
 664                 skb_orphan(skb);
 665                 skb_ext_reset(skb);
 666                 nf_reset_ct(skb);
 667                 skb->slow_gro = 0;
 668         }
 669
 670         napi->skb = skb;
 671 }
 672
 673 struct sk_buff *napi_get_frags(struct napi_struct *napi)
 674 {
 675         struct sk_buff *skb = napi->skb;
 676
 677         if (!skb) {
 678                 skb = napi_alloc_skb(napi, GRO_MAX_HEAD);
 679                 if (skb) {
 680                         napi->skb = skb;
 681                         skb_mark_napi_id(skb, napi);
 682                 }
 683         }
 684         return skb;
 685 }
 686 EXPORT_SYMBOL(napi_get_frags);
 687
 688 static gro_result_t napi_frags_finish(struct napi_struct *napi,
 689                                       struct sk_buff *skb,
 690                                       gro_result_t ret)
 691 {
 692         switch (ret) {
 693         case GRO_NORMAL:
 694         case GRO_HELD:
 695                 __skb_push(skb, ETH_HLEN);
 696                 skb->protocol = eth_type_trans(skb, skb->dev);
 697                 if (ret == GRO_NORMAL)
 698                         gro_normal_one(napi, skb, 1);
 699                 break;
 700
 701         case GRO_MERGED_FREE:
 702                 if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 703                         napi_skb_free_stolen_head(skb);
 704                 else
 705                         napi_reuse_skb(napi, skb);
 706                 break;
 707
 708         case GRO_MERGED:
 709         case GRO_CONSUMED:
 710                 break;
 711         }
 712
 713         return ret;
 714 }
 715
 716 /* Upper GRO stack assumes network header starts at gro_offset=0
 717  * Drivers could call both napi_gro_frags() and napi_gro_receive()
 718  * We copy ethernet header into skb->data to have a common layout.
 719  */
 720 static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
 721 {
 722         struct sk_buff *skb = napi->skb;
 723         const struct ethhdr *eth;
 724         unsigned int hlen = sizeof(*eth);
 725
 726         napi->skb = NULL;
 727
 728         skb_reset_mac_header(skb);
 729         skb_gro_reset_offset(skb, hlen);
 730
 731         if (unlikely(skb_gro_header_hard(skb, hlen))) {
 732                 eth = skb_gro_header_slow(skb, hlen, 0);
 733                 if (unlikely(!eth)) {
 734                         net_warn_ratelimited("%s: dropping impossible skb from %s\n",
 735                                              __func__, napi->dev->name);
 736                         napi_reuse_skb(napi, skb);
 737                         return NULL;
 738                 }
 739         } else {
 740                 eth = (const struct ethhdr *)skb->data;
 741                 gro_pull_from_frag0(skb, hlen);
 742                 NAPI_GRO_CB(skb)->frag0 += hlen;
 743                 NAPI_GRO_CB(skb)->frag0_len -= hlen;
 744         }
 745         __skb_pull(skb, hlen);
 746
 747         /*
 748          * This works because the only protocols we care about don't require
 749          * special handling.
 750          * We'll fix it up properly in napi_frags_finish()
 751          */
 752         skb->protocol = eth->h_proto;
 753
 754         return skb;
 755 }
 756
 757 gro_result_t napi_gro_frags(struct napi_struct *napi)
 758 {
 759         gro_result_t ret;
 760         struct sk_buff *skb = napi_frags_skb(napi);
 761
 762         trace_napi_gro_frags_entry(skb);
 763
 764         ret = napi_frags_finish(napi, skb, dev_gro_receive(napi, skb));
 765         trace_napi_gro_frags_exit(ret);
 766
 767         return ret;
 768 }
 769 EXPORT_SYMBOL(napi_gro_frags);
 770
 771 /* Compute the checksum from gro_offset and return the folded value
 772  * after adding in any pseudo checksum.
 773  */
 774 __sum16 __skb_gro_checksum_complete(struct sk_buff *skb)
 775 {
 776         __wsum wsum;
 777         __sum16 sum;
 778
 779         wsum = skb_checksum(skb, skb_gro_offset(skb), skb_gro_len(skb), 0);
 780
 781         /* NAPI_GRO_CB(skb)->csum holds pseudo checksum */
 782         sum = csum_fold(csum_add(NAPI_GRO_CB(skb)->csum, wsum));
 783         /* See comments in __skb_checksum_complete(). */
 784         if (likely(!sum)) {
 785                 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
 786                     !skb->csum_complete_sw)
 787                         netdev_rx_csum_fault(skb->dev, skb);
 788         }
 789
 790         NAPI_GRO_CB(skb)->csum = wsum;
 791         NAPI_GRO_CB(skb)->csum_valid = 1;
 792
 793         return sum;
 794 }
 795 EXPORT_SYMBOL(__skb_gro_checksum_complete);