perf evsel: Make perf_evsel__name() accept a NULL argument

[ Upstream commit fdbdd7e8580eac9bdafa532746c865644d125e34 ]

In which case it simply returns "unknown", like when it can't figure out
the evsel->name value.

This makes this code more robust and fixes a problem in 'perf trace'
where a NULL evsel was being passed to a routine that only used the
evsel for printing its name when a invalid syscall id was passed.

Reported-by: Leo Yan <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
1 file changed