svn commit: r286880 - head/sys/kern

[Julien Charbon]

 Hi Konstantin,

On 27/08/15 12:49, Konstantin Belousov wrote:
> On Wed, Aug 26, 2015 at 08:14:15PM +0200, Julien Charbon wrote:
>>  As I said, I am not opposed to back out this change, callout(9) API in
>> mpsafe mode is a already complex/subtle API, it won't change too much
>> the current complexity.
>>
>>  Let say that if nobody screams until Friday 8/28, I will put back
>> r284245 and revert this change _and_ I will make this case clear in the
>> man page.
> 
> [Replying to a random message in the whole set of conversations]
> 
> There is one more case, besides TCP timers, which is equially, of not
> more, critical and sensitive WRT to the callout_stop().  Look at the
> sys/kern/subr_sleepqueue.c:sleepq_check_timeout().  Stray return of
> the false result from callout_stop() causes creation of the non-killable
> processes:  the callout fired, we missed the wakeup and went to sleep
> by manually doing the context switch.  Such thread cannot be woken up.
> 
> I suspect that your fix is a better approach than my attempt to look
> at something similar at PR 200992 (may be not).

 This change (r286880) won't improve the PR 200992:

 r286880 only addresses a case where callout_stop() returns 1 instead of
0.  Thus the only thing that can do r286880 to PR 200992:

 - Don't change anything the issues
 - Worsen the issue

 Sorry to kill your hope of a simple and elegant fix for PR 200992.

--
Julien

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