5.4-stable review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu (Google) mhiramat@kernel.org
commit 0958b33ef5a04ed91f61cef4760ac412080c4e08 upstream.
Fix register_snapshot_trigger() to return error code if it failed to allocate a snapshot instead of 0 (success). Unless that, it will register snapshot trigger without an error.
Link: https://lore.kernel.org/linux-trace-kernel/170622977792.270660.2789298642759...
Fixes: 0bbe7f719985 ("tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation") Cc: stable@vger.kernel.org Cc: Vincent Donnefort vdonnefort@google.com Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/trace/trace_events_trigger.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -1140,8 +1140,10 @@ register_snapshot_trigger(char *glob, st struct event_trigger_data *data, struct trace_event_file *file) { - if (tracing_alloc_snapshot_instance(file->tr) != 0) - return 0; + int ret = tracing_alloc_snapshot_instance(file->tr); + + if (ret < 0) + return ret;
return register_trigger(glob, ops, data, file); }