svn commit: r302350 - in head: share/man/man9 sys/kern sys/sys

[Ngie Cooper (yaneurabeya)]

> On Jul 5, 2016, at 11:47, Gleb Smirnoff <glebius at FreeBSD.org> wrote:
> 
> Author: glebius
> Date: Tue Jul  5 18:47:17 2016
> New Revision: 302350
> URL: https://svnweb.freebsd.org/changeset/base/302350
> 
> Log:
>  The paradigm of a callout is that it has three consequent states:
>  not scheduled -> scheduled -> running -> not scheduled. The API and the
>  manual page assume that, some comments in the code assume that, and looks
>  like some contributors to the code also did. The problem is that this
>  paradigm isn't true. A callout can be scheduled and running at the same
>  time, which makes API description ambigouous. In such case callout_stop()
>  family of functions/macros should return 1 and 0 at the same time, since it
>  successfully unscheduled future callout but the current one is running.
>  Before this change we returned 1 in such a case, with an exception that
>  if running callout was migrating we returned 0, unless CS_MIGRBLOCK was
>  specified.
> 
>  With this change, we now return 0 in case if future callout was unscheduled,
>  but another one is still in action, indicating to API users that resources
>  are not yet safe to be freed.
> 
>  However, the sleepqueue code relies on getting 1 return code in that case,
>  and there already was CS_MIGRBLOCK flag, that covered one of the edge cases.
>  In the new return path we will also use this flag, to keep sleepqueue safe.
> 
>  Since the flag CS_MIGRBLOCK doesn't block migration and now isn't limited to
>  migration edge case, rename it to CS_EXECUTING.
> 
>  This change fixes panics on a high loaded TCP server.
> 
>  Reviewed by:	jch, hselasky, rrs, kib
>  Approved by:	re (gjb)
>  Differential Revision:	https://reviews.freebsd.org/D7042
> 
> Modified:
>  head/share/man/man9/timeout.9
>  head/sys/kern/kern_timeout.c
>  head/sys/kern/subr_sleepqueue.c
>  head/sys/sys/callout.h

Should __FreeBSD_version be bumped for the change?
Thanks,
-Ngie
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