[PATCH v2] perf probe: Return errno when does not hit any event

[Kefeng Wang <wangkefeng.wang@huawei.com>]

On old perf, when using perf probe -d to delete an inexistent event,
it return errno, eg,

-bash-4.3# perf probe -d xxx  || echo $?
Info: Event "*:xxx" does not exist.
  Error: Failed to delete events.
255

But now perf_del_probe_events() will always set ret = 0, different
from previous del_perf_probe_events(). After this, it return errno
again, eg,

-bash-4.3# ./perf probe -d xxx  || echo $?
"xxx" does not hit any event.
  Error: Failed to delete events.
254

And it is more appropriate to return -ENOENT instead of -EPERM.

Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>

Fixes: dddc7ee32fa1 ("perf probe: Fix an error when deleting probes successfully")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---

v1->v2:
- Using pr_wanring to show warning infos and drop inappropriate comment
  suggested by Masami Hiramatsu.

 tools/perf/builtin-probe.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 1fcebc3..51cdc23 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -442,9 +442,9 @@ static int perf_del_probe_events(struct strfilter *filter)
 	}
 
 	if (ret == -ENOENT && ret2 == -ENOENT)
-		pr_debug("\"%s\" does not hit any event.\n", str);
-		/* Note that this is silently ignored */
-	ret = 0;
+		pr_warning("\"%s\" does not hit any event.\n", str);
+	else
+		ret = 0;
 
 error:
 	if (kfd >= 0)
-- 
1.7.12.4