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| author | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-02-22 20:33:25 -0500 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-03-18 10:33:05 -0400 |
| commit | 2048fdc27525c6b32c63f8429d9335b7fd2f90c2 (patch) | |
| tree | f8f98c86b73f831623c317cda2eb01f9ee08a975 /kernel/trace | |
| parent | cca990c7b565af0dc61a8f647c00833453cf5bff (diff) | |
| download | linux-2048fdc27525c6b32c63f8429d9335b7fd2f90c2.tar.gz linux-2048fdc27525c6b32c63f8429d9335b7fd2f90c2.tar.bz2 linux-2048fdc27525c6b32c63f8429d9335b7fd2f90c2.zip | |
tracing: Decrement the snapshot if the snapshot trigger fails to register
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.
Link: https://lore.kernel.org/linux-trace-kernel/20240223013344.729055907@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Fixes: 16f7e48ffc53a ("tracing: Add snapshot refcount")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace_events_trigger.c | 5 |
1 files changed, 4 insertions, 1 deletions
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, |