Messages in this thread | | | Subject | Re: [PATCH 02/10] perf, trace: Use per-tracepoint-per-cpu hlist to track events | From | Peter Zijlstra <> | Date | Fri, 21 May 2010 12:19:09 +0200 |
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On Fri, 2010-05-21 at 12:13 +0200, Frederic Weisbecker wrote: > > I assumed that after probe unregister a tracepoint callback doesn't > > happen, which then guarantees we should never get !head.
> I'm not sure about this. The tracepoints are called under rcu_read_lock(), > but there is not synchronize_rcu() after we unregister a tracepoint, which > means you can have a pending preempted one somewhere. > > There is a call_rcu that removes the callbacks, but that only protect > the callback themselves.
Ah, ok, so we should do probe_unregister + synchronize_sched().
That should ensure __DO_TRACE() doesn't call into it anymore.
/me goes make a patch
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