Date: Tue, 18 Aug 2015 12:59:59 +0200 From: Hans Petter Selasky <hps@selasky.org> To: Julien Charbon <jch@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r286880 - head/sys/kern Message-ID: <55D3102F.6080206@selasky.org> In-Reply-To: <201508181015.t7IAFAex055889@repo.freebsd.org> References: <201508181015.t7IAFAex055889@repo.freebsd.org>
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On 08/18/15 12:15, Julien Charbon wrote: > Author: jch > Date: Tue Aug 18 10:15:09 2015 > New Revision: 286880 > URL: https://svnweb.freebsd.org/changeset/base/286880 > > Log: > callout_stop() should return 0 (fail) when the callout is currently > being serviced and indeed unstoppable. > > A scenario to reproduce this case is: > > - the callout is being serviced and at same time, > - callout_reset() is called on this callout that sets > the CALLOUT_PENDING flag and at same time, > - callout_stop() is called on this callout and returns 1 (success) > even if the callout is indeed currently running and unstoppable. > > This issue was caught up while making r284245 (D2763) workaround, and > was discussed at BSDCan 2015. Once applied the r284245 workaround > is not needed anymore and will be reverted. > > Differential Revision: https://reviews.freebsd.org/D3078 > Reviewed by: jhb > Sponsored by: Verisign, Inc. > > Modified: > head/sys/kern/kern_timeout.c > > Modified: head/sys/kern/kern_timeout.c > ============================================================================== > --- head/sys/kern/kern_timeout.c Tue Aug 18 10:07:03 2015 (r286879) > +++ head/sys/kern/kern_timeout.c Tue Aug 18 10:15:09 2015 (r286880) > @@ -1150,7 +1150,7 @@ _callout_stop_safe(struct callout *c, in > struct callout_cpu *cc, *old_cc; > struct lock_class *class; > int direct, sq_locked, use_lock; > - int not_on_a_list; > + int not_on_a_list, not_running; > > if (safe) > WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock, > @@ -1378,8 +1378,15 @@ again: > } > } > callout_cc_del(c, cc); > + > + /* > + * If we are asked to stop a callout which is currently in progress > + * and indeed impossible to stop then return 0. > + */ > + not_running = !(cc_exec_curr(cc, direct) == c); > + > CC_UNLOCK(cc); > - return (1); > + return (not_running); > } > > void > > Should this be MFC'ed to 10? --HPS
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