From d21f4f58c7e9bf6fc5f9dc0c824d3ab9c4f0e154 Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Wed, 16 Dec 2015 20:09:25 +0000 Subject: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive code [ Upstream commit 3822b5c2fc62e3de8a0f33806ff279fb7df92432 ] With b3ca9b02b00704053a38bfe4c31dbbb9c13595d0, the AF_UNIX SOCK_STREAM receive code was changed from using mutex_lock(&u->readlock) to mutex_lock_interruptible(&u->readlock) to prevent signals from being delayed for an indefinite time if a thread sleeping on the mutex happened to be selected for handling the signal. But this was never a problem with the stream receive code (as opposed to its datagram counterpart) as that never went to sleep waiting for new messages with the mutex held and thus, wouldn't cause secondary readers to block on the mutex waiting for the sleeping primary reader. As the interruptible locking makes the code more complicated in exchange for no benefit, change it back to using mutex_lock. Signed-off-by: Rainer Weikusat Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby --- net/unix/af_unix.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 9ce79ed792cd..31b88dcb0f01 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2088,14 +2088,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, memset(&tmp_scm, 0, sizeof(tmp_scm)); } - err = mutex_lock_interruptible(&u->readlock); - if (unlikely(err)) { - /* recvmsg() in non blocking mode is supposed to return -EAGAIN - * sk_rcvtimeo is not honored by mutex_lock_interruptible() - */ - err = noblock ? -EAGAIN : -ERESTARTSYS; - goto out; - } + mutex_lock(&u->readlock); if (flags & MSG_PEEK) skip = sk_peek_offset(sk, flags); @@ -2136,12 +2129,12 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, timeo = unix_stream_data_wait(sk, timeo, last); - if (signal_pending(current) - || mutex_lock_interruptible(&u->readlock)) { + if (signal_pending(current)) { err = sock_intr_errno(timeo); goto out; } + mutex_lock(&u->readlock); continue; unlock: unix_state_unlock(sk); -- 2.43.0