perf probe: Do not show the skipped events

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 <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: [e-mail]
Link: http://lore.kernel.org/lkml/158763968263.30755.12800484151476026340.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-probe.c

···
 
 		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,