From: "Steven Rostedt (Google)" <rost...@goodmis.org>
Running the ftrace selftests caused the ring buffer mapping test to fail.
Investigating, I found that the snapshot counter would be incremented
every time a snapshot trigger was added, even if that snapshot trigger
failed.
# cd /sys/kernel/tracing
# echo "snapshot" > events/sched/sched_process_fork/trigger
# echo "snapshot" > events/sched/sched_process_fork/trigger
-bash: echo: write error: File exists
That second one that fails increments the snapshot counter but doesn't
decrement it. It needs to be decremented when the snapshot fails.
Fixes: 16f7e48ffc53a ("tracing: Add snapshot refcount")
Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
kernel/trace/trace_events_trigger.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_events_trigger.c
b/kernel/trace/trace_events_trigger.c
index 62e4f58b8671..4bec043c8690 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -1491,7 +1491,10 @@ register_snapshot_trigger(char *glob,
if (ret < 0)
return ret;
- return register_trigger(glob, data, file);
+ ret = register_trigger(glob, data, file);
+ if (ret < 0)
+ tracing_disarm_snapshot(file->tr);
+ return ret;
}
static void unregister_snapshot_trigger(char *glob,
--
2.43.0
