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 16:18:18 +0200 |
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On Fri, 2010-05-21 at 10:04 -0400, Steven Rostedt wrote: > On Fri, 2010-05-21 at 11:02 +0200, Peter Zijlstra wrote: > > plain text document attachment (perf-trace-per-cpu-fold.patch) > > Avoid the swevent hash-table by using per-tracepoint hlists. > > > > Also, avoid conditionals on the fast path by ordering with probe unregister > > so that we should never get on the callback path without the data being there. > > > > > -void perf_trace_disable(int event_id) > > +void perf_trace_destroy(struct perf_event *p_event) > > { > > - struct ftrace_event_call *event; > > + struct ftrace_event_call *tp_event = p_event->tp_event; > > + int i; > > > > - mutex_lock(&event_mutex); > > - list_for_each_entry(event, &ftrace_events, list) { > > - if (event->id == event_id) { > > - perf_trace_event_disable(event); > > - module_put(event->mod); > > - break; > > + if (--tp_event->perf_refcount > 0) > > + return; > > + > > You remove the event_mutex and then update the tp_event->perf_refcount > without any protection. > > That tp_event->perf_refcount is global to the event not to the perf > event.
Oh, bugger, yes. I seem to have lost it on destroy..
Thanks!
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