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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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