From owner-svn-src-head@freebsd.org  Tue Sep  1 18:58:19 2015
Return-Path: <owner-svn-src-head@freebsd.org>
Delivered-To: svn-src-head@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 43F449C7396;
 Tue,  1 Sep 2015 18:58:19 +0000 (UTC)
 (envelope-from bdrewery@FreeBSD.org)
Received: from freefall.freebsd.org (freefall.freebsd.org
 [IPv6:2001:1900:2254:206c::16:87])
 by mx1.freebsd.org (Postfix) with ESMTP id 309AECB4;
 Tue,  1 Sep 2015 18:58:19 +0000 (UTC)
 (envelope-from bdrewery@FreeBSD.org)
Received: from mail.xzibition.com (localhost [IPv6:::1])
 by freefall.freebsd.org (Postfix) with ESMTP id 29BC61945;
 Tue,  1 Sep 2015 18:58:19 +0000 (UTC)
 (envelope-from bdrewery@FreeBSD.org)
Received: from mail.xzibition.com (localhost [172.31.3.2])
 by mail.xzibition.com (Postfix) with ESMTP id E4047FDB3;
 Tue,  1 Sep 2015 18:58:18 +0000 (UTC)
X-Virus-Scanned: amavisd-new at mail.xzibition.com
Received: from mail.xzibition.com ([172.31.3.2])
 by mail.xzibition.com (mail.xzibition.com [172.31.3.2]) (amavisd-new,
 port 10026)
 with LMTP id zzXAtODLAcGE; Tue,  1 Sep 2015 18:58:16 +0000 (UTC)
Subject: Re: svn commit: r287366 - head/sys/kern
DKIM-Filter: OpenDKIM Filter v2.9.2 mail.xzibition.com 88AF3FDAA
References: <201509011405.t81E5U0g025928@repo.freebsd.org>
 <20150901182636.GO33167@funkthat.com>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
From: Bryan Drewery <bdrewery@FreeBSD.org>
Organization: FreeBSD
Message-ID: <55E5F548.50007@FreeBSD.org>
Date: Tue, 1 Sep 2015 11:58:16 -0700
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0)
 Gecko/20100101 Thunderbird/38.2.0
MIME-Version: 1.0
In-Reply-To: <20150901182636.GO33167@funkthat.com>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
X-BeenThere: svn-src-head@freebsd.org
X-Mailman-Version: 2.1.20
Precedence: list
List-Id: SVN commit messages for the src tree for head/-current
 <svn-src-head.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head/>
List-Post: <mailto:svn-src-head@freebsd.org>
List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 01 Sep 2015 18:58:19 -0000

On 9/1/15 11:26 AM, John-Mark Gurney wrote:
> Konstantin Belousov wrote this message on Tue, Sep 01, 2015 at 14:05 +0000:
>> Author: kib
>> Date: Tue Sep  1 14:05:29 2015
>> New Revision: 287366
>> URL: https://svnweb.freebsd.org/changeset/base/287366
>>
>> Log:
>>   Exit notification for EVFILT_PROC removes knote from the knlist.  In
>>   particular, this invalidates the knote kn_link linkage, making the
>>   SLIST_FOREACH() loop accessing undefined values (e.g. trashed by
>>   QUEUE_MACRO_DEBUG).  If the knote is freed by other thread when kq
>>   lock is released or when influx is cleared, e.g. by knote_scan() for
>>   kqueue owning the knote, the iteration step would access freed memory.
>>   
>>   Use SLIST_FOREACH_SAFE() to fix iteration.
> 
> Please back this out immediately.
> 
> I objected to this change, and you did not give me enough time to
> properly address this change.
> 

FWIW we've had the same change in the Isilon codebase for some time as well.

-- 
Regards,
Bryan Drewery