5.15-stable review patch. If anyone has any objections, please let me know.
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From: Kuniyuki Iwashima kuniyu@amazon.com
[ Upstream commit a9bf9c7dc6a5899c01cb8f6e773a66315a5cd4b7 ]
As small optimisation, unix_stream_connect() prefetches the client's sk->sk_state without unix_state_lock() and checks if it's TCP_CLOSE.
Later, sk->sk_state is checked again under unix_state_lock().
Let's use READ_ONCE() for the first check and TCP_CLOSE directly for the second check.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/unix/af_unix.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)
--- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1331,7 +1331,6 @@ static int unix_stream_connect(struct so struct sock *other = NULL; struct sk_buff *skb = NULL; unsigned int hash; - int st; int err; long timeo;
@@ -1413,9 +1412,7 @@ restart:
Well, and we have to recheck the state after socket locked. */ - st = sk->sk_state; - - switch (st) { + switch (READ_ONCE(sk->sk_state)) { case TCP_CLOSE: /* This is ok... continue with connect */ break; @@ -1430,7 +1427,7 @@ restart:
unix_state_lock_nested(sk, U_LOCK_SECOND);
- if (sk->sk_state != st) { + if (sk->sk_state != TCP_CLOSE) { unix_state_unlock(sk); unix_state_unlock(other); sock_put(other);