Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754140AbbL0UAx (ORCPT ); Sun, 27 Dec 2015 15:00:53 -0500 Received: from mail-wm0-f43.google.com ([74.125.82.43]:36504 "EHLO mail-wm0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752651AbbL0UAt (ORCPT ); Sun, 27 Dec 2015 15:00:49 -0500 From: Nicolai Stange To: "David S. Miller" Subject: [PATCH] net, socket, socket_wq: fix missing initialization of flags CC: Eric Dumazet CC: Nicolai Stange CC: netdev@vger.kernel.org CC: linux-kernel@vger.kernel.org Date: Sun, 27 Dec 2015 21:00:45 +0100 Message-ID: <87ege73bma.fsf@gmail.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1962 Lines: 49 Fixes: ceb5d58b2170 ("net: fix sock_wake_async() rcu protection") Commit ceb5d58b2170 ("net: fix sock_wake_async() rcu protection") from the current 4.4 release cycle introduces a new flags member in struct socket_wq and moved SOCKWQ_ASYNC_NOSPACE and SOCKWQ_ASYNC_WAITDATA from struct socket's flags member into that new place. Unfortunately, the new flags field is never initialized properly, at least not for the struct socket_wq instance created in sock_alloc_inode(). One particular issue I encountered because of this is that my GNU Emacs failed to draw anything on my desktop -- i.e. what I got is a transparent window, including the title bar. Bisection lead to the commit mentioned above and further investigation by means of strace told me that Emacs is indeed speaking to my Xorg through an O_ASYNC AF_UNIX socket. This is reproducible 100% of times and the fact that properly initializing the struct socket_wq ->flags fixes the issue leads me to the conclusion that somehow SOCKWQ_ASYNC_NOSPACE got set in the uninitialized ->flags, preventing my Emacs from receiving any SIGIO's due to send space becoming available again and it got stuck. Make sock_alloc_inode() set the newly created struct socket_wq's ->flags member to zero. Signed-off-by: Nicolai Stange --- net/socket.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/socket.c b/net/socket.c index 29822d6..d730ef9 100644 --- a/net/socket.c +++ b/net/socket.c @@ -257,6 +257,7 @@ static struct inode *sock_alloc_inode(struct super_block *sb) } init_waitqueue_head(&wq->wait); wq->fasync_list = NULL; + wq->flags = 0; RCU_INIT_POINTER(ei->socket.wq, wq); ei->socket.state = SS_UNCONNECTED; -- 2.6.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/