Patch "net: unix: non blocking recvmsg() should not return -EINTR" has been added to the 3.10-stable tree

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This is a note to let you know that I've just added the patch titled

    net: unix: non blocking recvmsg() should not return -EINTR

to the 3.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-unix-non-blocking-recvmsg-should-not-return-eintr.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From foo@baz Fri Apr 11 08:46:36 PDT 2014
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Tue, 25 Mar 2014 18:42:27 -0700
Subject: net: unix: non blocking recvmsg() should not return -EINTR

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit de1443916791d75fdd26becb116898277bb0273f ]

Some applications didn't expect recvmsg() on a non blocking socket
could return -EINTR. This possibility was added as a side effect
of commit b3ca9b02b00704 ("net: fix multithreaded signal handling in
unix recv routines").

To hit this bug, you need to be a bit unlucky, as the u->readlock
mutex is usually held for very small periods.

Fixes: b3ca9b02b00704 ("net: fix multithreaded signal handling in unix recv routines")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Rainer Weikusat <rweikusat@xxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/unix/af_unix.c |   17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1792,8 +1792,11 @@ static int unix_dgram_recvmsg(struct kio
 		goto out;
 
 	err = mutex_lock_interruptible(&u->readlock);
-	if (err) {
-		err = sock_intr_errno(sock_rcvtimeo(sk, noblock));
+	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;
 	}
 
@@ -1913,6 +1916,7 @@ static int unix_stream_recvmsg(struct ki
 	struct unix_sock *u = unix_sk(sk);
 	struct sockaddr_un *sunaddr = msg->msg_name;
 	int copied = 0;
+	int noblock = flags & MSG_DONTWAIT;
 	int check_creds = 0;
 	int target;
 	int err = 0;
@@ -1928,7 +1932,7 @@ static int unix_stream_recvmsg(struct ki
 		goto out;
 
 	target = sock_rcvlowat(sk, flags&MSG_WAITALL, size);
-	timeo = sock_rcvtimeo(sk, flags&MSG_DONTWAIT);
+	timeo = sock_rcvtimeo(sk, noblock);
 
 	/* Lock the socket to prevent queue disordering
 	 * while sleeps in memcpy_tomsg
@@ -1940,8 +1944,11 @@ static int unix_stream_recvmsg(struct ki
 	}
 
 	err = mutex_lock_interruptible(&u->readlock);
-	if (err) {
-		err = sock_intr_errno(timeo);
+	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;
 	}
 


Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are

queue-3.10/inet-frag-make-sure-forced-eviction-removes-all-frags.patch
queue-3.10/tcp-tcp_release_cb-should-release-socket-ownership.patch
queue-3.10/net-unix-non-blocking-recvmsg-should-not-return-eintr.patch
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