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SubjectRe: [Bugfix] unregister_trace_probe needs to be called under mutex
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On Wed, 2010-06-30 at 14:15 +0530, Srikar Dronamraju wrote:
> Comment in unregister_trace_probe() says probe_lock will be held
> when it gets called. However there is a case where it might called
> without the probe_lock being held. Also since we are traversing the
> probe_list and deleting an element from the probe_list, probe_lock
> should be held.
>
> This was first pointed in uprobes traceevent review by Frederic
> Weisbecker here. (http://lkml.org/lkml/2010/5/12/106)
>
> This patch is needed for both 2.6.35-rc3 and 2.6.35-rc3-tip
>
> Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> ---
>
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 4f11a56..67670cd 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -269,14 +269,17 @@ static int create_trace_probe(int argc, char **argv)
> pr_info("Delete command needs an event name.\n");
> return -EINVAL;
> }
> + mutex_lock(&probe_lock);
> tp = find_probe_event(event, group);
> if (!tp) {
> + mutex_unlock(&probe_lock);
> pr_info("Event %s/%s doesn't exist.\n", group, event);
> return -ENOENT;
> }
> /* delete an event */
> unregister_trace_probe(tp);
> free_trace_probe(tp);
> + mutex_unlock(&probe_lock);
> return 0;
> }

Shouldn't all that go through steven's ->reg() interface?


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