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Date: Tue, 1 Sep 2015 11:26:36 -0700
From: John-Mark Gurney <jmg@funkthat.com>
To: Konstantin Belousov <kib@freebsd.org>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: Re: svn commit: r287366 - head/sys/kern
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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.

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."