From c32f0bd7d4838982c6724fca0da92353f27c6f88 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Thu, 16 Jan 2025 14:34:35 +0900 Subject: [PATCH] af_unix: Set drop reason in unix_release_sock(). unix_release_sock() is called when the last refcnt of struct file is released. Let's define a new drop reason SKB_DROP_REASON_SOCKET_CLOSE and set it for kfree_skb() in unix_release_sock(). # echo 1 > /sys/kernel/tracing/events/skb/kfree_skb/enable # python3 >>> from socket import * >>> s1, s2 = socketpair(AF_UNIX) >>> s1.send(b'hello world') >>> s2.close() # cat /sys/kernel/tracing/trace_pipe ... python3-280 ... kfree_skb: ... protocol=0 location=unix_release_sock+0x260/0x420 reason: SOCKET_CLOSE To be precise, unix_release_sock() is also called for a new child socket in unix_stream_connect() when something fails, but the new sk does not have skb in the recv queue then and no event is logged. Note that only tcp_inbound_ao_hash() uses a similar drop reason, SKB_DROP_REASON_TCP_CLOSE, and this can be generalised later. Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250116053441.5758-3-kuniyu@amazon.com Signed-off-by: Jakub Kicinski --- include/net/dropreason-core.h | 3 +++ net/unix/af_unix.c | 4 ++-- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h index f3714cbea50d8..b9e7ff853ce36 100644 --- a/include/net/dropreason-core.h +++ b/include/net/dropreason-core.h @@ -6,6 +6,7 @@ #define DEFINE_DROP_REASON(FN, FNe) \ FN(NOT_SPECIFIED) \ FN(NO_SOCKET) \ + FN(SOCKET_CLOSE) \ FN(SOCKET_FILTER) \ FN(SOCKET_RCVBUFF) \ FN(PKT_TOO_SMALL) \ @@ -138,6 +139,8 @@ enum skb_drop_reason { * 3) no valid child socket during 3WHS process */ SKB_DROP_REASON_NO_SOCKET, + /** @SKB_DROP_REASON_SOCKET_CLOSE: socket is close()d */ + SKB_DROP_REASON_SOCKET_CLOSE, /** @SKB_DROP_REASON_SOCKET_FILTER: dropped by socket filter */ SKB_DROP_REASON_SOCKET_FILTER, /** @SKB_DROP_REASON_SOCKET_RCVBUFF: socket receive buff is full */ diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 8f2b605ce5b37..a05d25cc5545e 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -715,8 +715,8 @@ static void unix_release_sock(struct sock *sk, int embrion) if (state == TCP_LISTEN) unix_release_sock(skb->sk, 1); - /* passed fds are erased in the kfree_skb hook */ - kfree_skb(skb); + /* passed fds are erased in the kfree_skb hook */ + kfree_skb_reason(skb, SKB_DROP_REASON_SOCKET_CLOSE); } if (path.dentry)