Messages in this thread | | | Subject | Re: [PATCH] tracing/profile: Fix profile_disable vs module_unload | From | Peter Zijlstra <> | Date | Mon, 24 Aug 2009 08:01:00 +0200 |
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On Mon, 2009-08-24 at 12:19 +0800, Li Zefan wrote: > If the correspoding module is unloaded before ftrace_profile_disable() > is called, event->profile_disable() won't be called, which can > cause oops: > > # insmod trace-events-sample.ko > # perf record -f -a -e sample:foo_bar sleep 3 & > # sleep 1 > # rmmod trace_events_sample > # insmod trace-events-sample.ko > OOPS! > > Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Hrmm, feel fragile, why don't we check if all a modules tracepoints are unused on unload?
> --- > kernel/trace/trace_event_profile.c | 5 ++++- > 1 files changed, 4 insertions(+), 1 deletions(-) > > diff --git a/kernel/trace/trace_event_profile.c b/kernel/trace/trace_event_profile.c > index 11ba5bb..55a25c9 100644 > --- a/kernel/trace/trace_event_profile.c > +++ b/kernel/trace/trace_event_profile.c > @@ -5,6 +5,7 @@ > * > */ > > +#include <linux/module.h> > #include "trace.h" > > int ftrace_profile_enable(int event_id) > @@ -14,7 +15,8 @@ int ftrace_profile_enable(int event_id) > > mutex_lock(&event_mutex); > list_for_each_entry(event, &ftrace_events, list) { > - if (event->id == event_id && event->profile_enable) { > + if (event->id == event_id && event->profile_enable && > + try_module_get(event->mod)) { > ret = event->profile_enable(event); > break; > } > @@ -32,6 +34,7 @@ void ftrace_profile_disable(int event_id) > list_for_each_entry(event, &ftrace_events, list) { > if (event->id == event_id) { > event->profile_disable(event); > + module_put(event->mod); > break; > } > }
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