From de1443916791d75fdd26becb116898277bb0273f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 25 Mar 2014 18:42:27 -0700 Subject: [PATCH] net: unix: non blocking recvmsg() should not return -EINTR 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 Cc: Rainer Weikusat Signed-off-by: David S. Miller --- net/unix/af_unix.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index ce6ec6c2f4d..94404f19f9d 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1787,8 +1787,11 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock, 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 kiocb *iocb, struct socket *sock, struct unix_sock *u = unix_sk(sk); DECLARE_SOCKADDR(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 kiocb *iocb, struct socket *sock, 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 kiocb *iocb, struct socket *sock, } 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; } -- 2.43.2