perf trace: Filter out POLLHUP'ed file descriptors

So that we don't continue polling on vanished file descriptors, i.e.
file descriptors for events monitoring threads that exited.

I.e. the following 'trace' command now exits as expected, instead
of staying in an eternal loop:

      $ sleep 5s &
      $ trace -p `pidof sleep`

Reported-by: Jiri Olsa <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Don Zickus <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 6 insertions, 1 deletions

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index b8fedf3f9921..fe39dc620179 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -2044,6 +2044,7 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
 	int err = -1, i;
 	unsigned long before;
 	const bool forks = argc > 0;
+	bool draining = false;
 	char sbuf[STRERR_BUFSIZE];
 
 	trace->live = true;
@@ -2171,8 +2172,12 @@ next_event:
 	if (trace->nr_events == before) {
 		int timeout = done ? 100 : -1;
 
-		if (perf_evlist__poll(evlist, timeout) > 0)
+		if (!draining && perf_evlist__poll(evlist, timeout) > 0) {
+			if (perf_evlist__filter_pollfd(evlist, POLLERR | POLLHUP) == 0)
+				draining = true;
+
 			goto again;
+		}
 	} else {
 		goto again;
 	}