From 2f57dd94bdef083855366138646b26b05f410d99 Mon Sep 17 00:00:00 2001 From: Yan Zhai Date: Mon, 4 Dec 2023 11:33:28 -0800 Subject: [PATCH] packet: add a generic drop reason for receive Commit da37845fdce2 ("packet: uses kfree_skb() for errors.") switches from consume_skb to kfree_skb to improve error handling. However, this could bring a lot of noises when we monitor real packet drops in kfree_skb[1], because in tpacket_rcv or packet_rcv only packet clones can be freed, not actual packets. Adding a generic drop reason to allow distinguish these "clone drops". [1]: https://lore.kernel.org/netdev/CABWYdi00L+O30Q=Zah28QwZ_5RU-xcxLFUK2Zj08A8MrLk9jzg@mail.gmail.com/ Fixes: da37845fdce2 ("packet: uses kfree_skb() for errors.") Suggested-by: Eric Dumazet Suggested-by: Willem de Bruijn Signed-off-by: Yan Zhai Reviewed-by: Eric Dumazet Reviewed-by: Willem de Bruijn Link: https://lore.kernel.org/r/ZW4piNbx3IenYnuw@debian.debian Signed-off-by: Jakub Kicinski --- include/net/dropreason-core.h | 6 ++++++ net/packet/af_packet.c | 20 +++++++------------- 2 files changed, 13 insertions(+), 13 deletions(-) diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h index 3c70ad53a49c..278e4c7d465c 100644 --- a/include/net/dropreason-core.h +++ b/include/net/dropreason-core.h @@ -86,6 +86,7 @@ FN(IPV6_NDISC_NS_OTHERHOST) \ FN(QUEUE_PURGE) \ FN(TC_ERROR) \ + FN(PACKET_SOCK_ERROR) \ FNe(MAX) /** @@ -378,6 +379,11 @@ enum skb_drop_reason { SKB_DROP_REASON_QUEUE_PURGE, /** @SKB_DROP_REASON_TC_ERROR: generic internal tc error. */ SKB_DROP_REASON_TC_ERROR, + /** + * @SKB_DROP_REASON_PACKET_SOCK_ERROR: generic packet socket errors + * after its filter matches an incoming packet. + */ + SKB_DROP_REASON_PACKET_SOCK_ERROR, /** * @SKB_DROP_REASON_MAX: the maximum of core drop reasons, which * shouldn't be used as a real 'reason' - only for tracing code gen diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index a84e00b5904b..f92edba4c40f 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2121,13 +2121,13 @@ static int packet_rcv_vnet(struct msghdr *msg, const struct sk_buff *skb, static int packet_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) { + enum skb_drop_reason drop_reason = SKB_CONSUMED; struct sock *sk; struct sockaddr_ll *sll; struct packet_sock *po; u8 *skb_head = skb->data; int skb_len = skb->len; unsigned int snaplen, res; - bool is_drop_n_account = false; if (skb->pkt_type == PACKET_LOOPBACK) goto drop; @@ -2217,9 +2217,9 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, return 0; drop_n_acct: - is_drop_n_account = true; atomic_inc(&po->tp_drops); atomic_inc(&sk->sk_drops); + drop_reason = SKB_DROP_REASON_PACKET_SOCK_ERROR; drop_n_restore: if (skb_head != skb->data && skb_shared(skb)) { @@ -2227,16 +2227,14 @@ drop_n_restore: skb->len = skb_len; } drop: - if (!is_drop_n_account) - consume_skb(skb); - else - kfree_skb(skb); + kfree_skb_reason(skb, drop_reason); return 0; } static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) { + enum skb_drop_reason drop_reason = SKB_CONSUMED; struct sock *sk; struct packet_sock *po; struct sockaddr_ll *sll; @@ -2250,7 +2248,6 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct sk_buff *copy_skb = NULL; struct timespec64 ts; __u32 ts_status; - bool is_drop_n_account = false; unsigned int slot_id = 0; int vnet_hdr_sz = 0; @@ -2498,19 +2495,16 @@ drop_n_restore: skb->len = skb_len; } drop: - if (!is_drop_n_account) - consume_skb(skb); - else - kfree_skb(skb); + kfree_skb_reason(skb, drop_reason); return 0; drop_n_account: spin_unlock(&sk->sk_receive_queue.lock); atomic_inc(&po->tp_drops); - is_drop_n_account = true; + drop_reason = SKB_DROP_REASON_PACKET_SOCK_ERROR; sk->sk_data_ready(sk); - kfree_skb(copy_skb); + kfree_skb_reason(copy_skb, drop_reason); goto drop_n_restore; } -- 2.20.1