svn commit: r287366 - head/sys/kern

[Bryan Drewery]

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