Messages in this thread | | | Date | Mon, 1 Jul 2019 10:24:30 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH] perf: Fix race between close() and fork() |
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On Fri, Jun 28, 2019 at 10:46:08PM +0200, Peter Zijlstra wrote: > On Fri, Jun 28, 2019 at 05:50:03PM +0100, Mark Rutland wrote: > > > + /* > > > + * Wake any perf_event_free_task() waiting for this event to be > > > + * freed. > > > + */ > > > + smp_mb(); /* pairs with wait_var_event() */ > > > + wake_up_var(var); > > > > Huh, so wake_up_var() doesn't imply a RELEASE? > > > > As an aside, doesn't that mean all callers of wake_up_var() have to do > > likewise to ensure it isn't re-ordered with whatever prior stuff they're > > trying to notify waiters about? Several do an smp_store_release() then a > > wake_up_var(), but IIUC the wake_up_var() could get pulled before that > > release... > > Yah,... > > https://lkml.kernel.org/r/20190624165012.GH3436@hirez.programming.kicks-ass.net
That gets me a 404, so I'll assume that's a speculative store. ;)
> I needs to get back to that.
Ouch; sorry for reminding you of this mess!
Thanks, Mark.
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