[PATCH 3/3] tracing/kprobes: unregister_trace_probe needs to be called under mutex

From: Arnaldo Carvalho de Melo
Date: Wed Aug 04 2010 - 17:26:26 EST

From: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>

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)

Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
LKML-Reference: <20100630084548.GA10325@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
kernel/trace/trace_kprobe.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1b79d1c..8b27c98 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -925,14 +925,17 @@ 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 */
+ mutex_unlock(&probe_lock);
return 0;


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