linux-kernel - [PATCH 4.9 127/128] perf probe: Do not show the skipped events

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Date:   Fri, 19 Jun 2020 16:33:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Masami Hiramatsu <mhiramat@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>
Subject: [PATCH 4.9 127/128] perf probe: Do not show the skipped events

From: Masami Hiramatsu <mhiramat@...nel.org>

commit f41ebe9defacddeae96a872a33f0f22ced0bfcef upstream.

When a probe point is expanded to several places (like inlined) and if
some of them are skipped because of blacklisted or __init function,
those trace_events has no event name. It must be skipped while showing
results.

Without this fix, you can see "(null):(null)" on the list,

  # ./perf probe request_resource
  reserve_setup is out of .text, skip it.
  Added new events:
    (null):(null)        (on request_resource)
    probe:request_resource (on request_resource)

  You can now use it in all perf tools, such as:

  	perf record -e probe:request_resource -aR sleep 1

  #

With this fix, it is ignored:

  # ./perf probe request_resource
  reserve_setup is out of .text, skip it.
  Added new events:
    probe:request_resource (on request_resource)

  You can now use it in all perf tools, such as:

  	perf record -e probe:request_resource -aR sleep 1

  #

Fixes: 5a51fcd1f30c ("perf probe: Skip kernel symbols which is out of .text")
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: stable@...r.kernel.org
Link: http://lore.kernel.org/lkml/158763968263.30755.12800484151476026340.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -344,6 +344,9 @@ static int perf_add_probe_events(struct
 
 		for (k = 0; k < pev->ntevs; k++) {
 			struct probe_trace_event *tev = &pev->tevs[k];
+			/* Skipped events have no event name */
+			if (!tev->event)
+				continue;
 
 			/* We use tev's name for showing new events */
 			show_perf_probe_event(tev->group, tev->event, pev,