Messages in this thread |  | | | Subject | Re: [PATCH 02/10] perf, trace: Use per-tracepoint-per-cpu hlist to track events | | From | Steven Rostedt <> | | Date | Fri, 21 May 2010 10:04:03 -0400 |
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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.
-- Steve
> + tp_event->perf_event_disable(tp_event); > + > + free_percpu(tp_event->perf_events); > + tp_event->perf_events = NULL; > + > + if (!--total_ref_count) { > + for (i = 0; i < 4; i++) { > + free_percpu(perf_trace_buf[i]); > + perf_trace_buf[i] = NULL; > } > } > - mutex_unlock(&event_mutex); > } >
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