[PATCH net-next] tcp: annotate data-race around queue->synflood_warned

[PATCH net-next] tcp: annotate data-race around queue->synflood_warned

[Eric Dumazet]

Annotate the lockless read of queue->synflood_warned.

Following xchg() has the needed data-race resolution.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp_input.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 94024fdc2da1b28af1b3b6e50735bf6b915f861d..0ae291e53eab228ce171cd73abafc009d99b886d 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6841,7 +6841,7 @@ static bool tcp_syn_flood_action(const struct sock *sk, const char *proto)
 #endif
 		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
 
-	if (!queue->synflood_warned && syncookies != 2 &&
+	if (!READ_ONCE(queue->synflood_warned) && syncookies != 2 &&
 	    xchg(&queue->synflood_warned, 1) == 0) {
 		if (IS_ENABLED(CONFIG_IPV6) && sk->sk_family == AF_INET6) {
 			net_info_ratelimited("%s: Possible SYN flooding on port [%pI6c]:%u. %s.\n",
-- 
2.38.1.431.g37b22c650d-goog

Re: [PATCH net-next] tcp: annotate data-race around queue->synflood_warned

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:

On Tue, 15 Nov 2022 09:18:51 +0000 you wrote:
> Annotate the lockless read of queue->synflood_warned.
> 
> Following xchg() has the needed data-race resolution.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
>  net/ipv4/tcp_input.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Here is the summary with links:
  - [net-next] tcp: annotate data-race around queue->synflood_warned
    https://git.kernel.org/netdev/net-next/c/bf36267e3ad3

You are awesome, thank you!
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