[PATCH 4.18 316/350] tracing: Return -ENOENT if there is no target synthetic event

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Masami Hiramatsu <mhiramat@xxxxxxxxxx>

commit 18858511fd8a877303cc34c06efa461b26a0e070 upstream.

Return -ENOENT error if there is no target synthetic event.
This notices an operation failure to user as below;

  # echo 'wakeup_latency u64 lat; pid_t pid;' > synthetic_events
  # echo '!wakeup' >> synthetic_events
  sh: write error: No such file or directory

Link: http://lkml.kernel.org/r/154013449986.25576.9487131386597290172.stgit@devbox

Acked-by: Tom Zanussi <zanussi@xxxxxxxxxxxxxxx>
Tested-by: Tom Zanussi <zanussi@xxxxxxxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Rajvi Jingar <rajvi.jingar@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 4b147936fa50 ('tracing: Add support for 'synthetic' events')
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/trace/trace_events_hist.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1072,8 +1072,10 @@ static int create_synth_event(int argc,
 		event = NULL;
 		ret = -EEXIST;
 		goto out;
-	} else if (delete_event)
+	} else if (delete_event) {
+		ret = -ENOENT;
 		goto out;
+	}
 
 	if (argc < 2) {
 		ret = -EINVAL;