From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753173AbaIVDjv (ORCPT ); Sun, 21 Sep 2014 23:39:51 -0400 Received: from mail-qc0-f169.google.com ([209.85.216.169]:46161 "EHLO mail-qc0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751464AbaIVDju (ORCPT ); Sun, 21 Sep 2014 23:39:50 -0400 Date: Sun, 21 Sep 2014 23:39:46 -0400 From: Tejun Heo To: Yifan Zhang Cc: Jing Xiang , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] workqueue: fix a workqueue kernel panic issue. Message-ID: <20140922033946.GA23583@htj.dyndns.org> References: <1410941884-26034-1-git-send-email-zhangyf@marvell.com> <4737A960563B524DA805CA602BE04B307EEE6C2694@SC-VEXCH2.marvell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4737A960563B524DA805CA602BE04B307EEE6C2694@SC-VEXCH2.marvell.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 21, 2014 at 08:30:32PM -0700, Yifan Zhang wrote: > Hi Tejun, > > What's do you think of this patch ? Any concern ? Hmmm? Haven't I already responded to this patch? > -----Original Message----- > From: Yifan Zhang [mailto:zhangyf@marvell.com] > Sent: 2014年9月17日 16:18 > To: Tejun Heo; Jing Xiang; linux-kernel@vger.kernel.org > Cc: Yifan Zhang > Subject: [PATCH] workqueue: fix a workqueue kernel panic issue. > > if created workqueue in multi-thread unsynchronized, Can you please elaborate? > get_work_pwq() may return NULL, which cause kernel panic. Judge get_work_pwq() return value before use > pwq->wq->flags. > > Signed-off-by: Yifan Zhang > --- > kernel/workqueue.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 5dbe22a..d3ac87f 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -1947,9 +1947,19 @@ __acquires(&pool->lock) { > struct pool_workqueue *pwq = get_work_pwq(work); > struct worker_pool *pool = worker->pool; > - bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; > + bool cpu_intensive; > int work_color; > struct worker *collision; > + > + if (pwq == NULL) { > + pr_err("BUG: invalid struct work_struct.data %lu\n", > + atomic_long_read(&work->data)); > + dump_stack(); > + return; I have difficult time seeing how the above piece of code would be acceptable but maybe the situation you're trying to explain is weird enough to justify it. Thanks. -- tejun