5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
