Messages in this thread | | | Subject | Re: [PATCH 2/5] perf: Support disable() after stop() on software events | From | Peter Zijlstra <> | Date | Thu, 10 Jun 2010 12:50:17 +0200 |
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On Thu, 2010-06-10 at 05:49 +0200, Frederic Weisbecker wrote: > If we call perf_event_stop() on a software event and then the > disable() pmu callback on them after that, we'll call twice > hlist_del_rcu() on the same hlist node and then bring a crash > by dereferencing LIST_POISON2. > > Just use hlist_del_init_rcu() instead to fix this problem. > > This preparates for new context exclusions. > > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Stephane Eranian <eranian@google.com> > Cc: Cyrill Gorcunov <gorcunov@gmail.com> > Cc: Zhang Yanmin <yanmin_zhang@linux.intel.com> > Cc: Steven Rostedt <rostedt@goodmis.org> > --- > kernel/perf_event.c | 2 +- > kernel/trace/trace_event_perf.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/perf_event.c b/kernel/perf_event.c > index 5c004f7..2d818bc 100644 > --- a/kernel/perf_event.c > +++ b/kernel/perf_event.c > @@ -4291,7 +4291,7 @@ static int perf_swevent_enable(struct perf_event *event) > > static void perf_swevent_disable(struct perf_event *event) > { > - hlist_del_rcu(&event->hlist_entry); > + hlist_del_init_rcu(&event->hlist_entry); > } > > static void perf_swevent_void(struct perf_event *event) > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c > index 4799d70..7bc1f26 100644 > --- a/kernel/trace/trace_event_perf.c > +++ b/kernel/trace/trace_event_perf.c > @@ -122,7 +122,7 @@ int perf_trace_enable(struct perf_event *p_event) > > void perf_trace_disable(struct perf_event *p_event) > { > - hlist_del_rcu(&p_event->hlist_entry); > + hlist_del_init_rcu(&p_event->hlist_entry); > } > > void perf_trace_destroy(struct perf_event *p_event)
Ok, so then why did you need the first patch?
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