Commit 9d819664 authored by Rainer Weikusat's avatar Rainer Weikusat Committed by Luis Henriques

af_unix: Revert 'lock_interruptible' in stream receive code

commit 3822b5c2 upstream.

With b3ca9b02, 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: default avatarRainer Weikusat <rweikusat@mobileactivedefense.com>
Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 2296bb5b
...@@ -2096,14 +2096,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, ...@@ -2096,14 +2096,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
memset(&tmp_scm, 0, sizeof(tmp_scm)); memset(&tmp_scm, 0, sizeof(tmp_scm));
} }
err = mutex_lock_interruptible(&u->readlock); mutex_lock(&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;
}
if (flags & MSG_PEEK) if (flags & MSG_PEEK)
skip = sk_peek_offset(sk, flags); skip = sk_peek_offset(sk, flags);
...@@ -2144,12 +2137,12 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock, ...@@ -2144,12 +2137,12 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
timeo = unix_stream_data_wait(sk, timeo, last); timeo = unix_stream_data_wait(sk, timeo, last);
if (signal_pending(current) if (signal_pending(current)) {
|| mutex_lock_interruptible(&u->readlock)) {
err = sock_intr_errno(timeo); err = sock_intr_errno(timeo);
goto out; goto out;
} }
mutex_lock(&u->readlock);
continue; continue;
unlock: unlock:
unix_state_unlock(sk); unix_state_unlock(sk);
......
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