From patchwork Fri Jan 22 23:28:25 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 571949 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 090661402C4; Sat, 23 Jan 2016 10:32:50 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1aMlCA-0004Fg-SU; Fri, 22 Jan 2016 23:32:46 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1aMlA5-0003A2-MB for kernel-team@lists.ubuntu.com; Fri, 22 Jan 2016 23:30:37 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1aMlA5-0007id-4R; Fri, 22 Jan 2016 23:30:37 +0000 Received: from kamal by fourier with local (Exim 4.82) (envelope-from ) id 1aMlA2-0007nH-CP; Fri, 22 Jan 2016 15:30:34 -0800 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.13.y-ckt 012/108] af_unix: Revert 'lock_interruptible' in stream receive code Date: Fri, 22 Jan 2016 15:28:25 -0800 Message-Id: <1453505401-29377-13-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1453505401-29377-1-git-send-email-kamal@canonical.com> References: <1453505401-29377-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Cc: Kamal Mostafa , Rainer Weikusat , "David S. Miller" X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.13.11-ckt33 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Rainer Weikusat [ 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: Kamal Mostafa --- 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 9ce79ed..31b88dc 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 @@ again: 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);