From f278b6d5bb465c7fd66f3d103812947e55b376ed Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 31 Mar 2025 07:59:46 +0000 Subject: Revert "tcp: avoid atomic operations on sk->sk_rmem_alloc" This reverts commit 0de2a5c4b824da2205658ebebb99a55c43cdf60f. I forgot that a TCP socket could receive messages in its error queue. sock_queue_err_skb() can be called without socket lock being held, and changes sk->sk_rmem_alloc. The fact that skbs in error queue are limited by sk->sk_rcvbuf means that error messages can be dropped if socket receive queues are full, which is an orthogonal issue. In future kernels, we could use a separate sk->sk_error_mem_alloc counter specifically for the error queue. Fixes: 0de2a5c4b824 ("tcp: avoid atomic operations on sk->sk_rmem_alloc") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250331075946.31960-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/ipv4/tcp.c | 18 ++---------------- 1 file changed, 2 insertions(+), 16 deletions(-) (limited to 'net/ipv4/tcp.c') diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index ea8de00f669d..6edc441b3702 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1525,25 +1525,11 @@ void tcp_cleanup_rbuf(struct sock *sk, int copied) __tcp_cleanup_rbuf(sk, copied); } -/* private version of sock_rfree() avoiding one atomic_sub() */ -void tcp_sock_rfree(struct sk_buff *skb) -{ - struct sock *sk = skb->sk; - unsigned int len = skb->truesize; - - sock_owned_by_me(sk); - atomic_set(&sk->sk_rmem_alloc, - atomic_read(&sk->sk_rmem_alloc) - len); - - sk_forward_alloc_add(sk, len); - sk_mem_reclaim(sk); -} - static void tcp_eat_recv_skb(struct sock *sk, struct sk_buff *skb) { __skb_unlink(skb, &sk->sk_receive_queue); - if (likely(skb->destructor == tcp_sock_rfree)) { - tcp_sock_rfree(skb); + if (likely(skb->destructor == sock_rfree)) { + sock_rfree(skb); skb->destructor = NULL; skb->sk = NULL; return skb_attempt_defer_free(skb); -- cgit v1.2.3