[tip:perf/core] perf sched timehist: Handle zero sample->tid properly

[tip-bot for Namhyung Kim]

Commit-ID:  5d92d96a947a5d0d83710d11750bb29a0c1b985d
Gitweb:     http://git.kernel.org/tip/5d92d96a947a5d0d83710d11750bb29a0c1b985d
Author:     Namhyung Kim <namhyung@xxxxxxxxxx>
AuthorDate: Tue, 6 Dec 2016 12:40:03 +0900
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Wed, 7 Dec 2016 12:00:34 -0300

perf sched timehist: Handle zero sample->tid properly

Sometimes samples have tid of 0 but non-0 pid.  It ends up having a new
thread of 0 tid/pid (instead of referring idle task) since tid is used
to search matching task.  But I guess it's wrong to use 0 as a tid when
pid is set.  This patch uses tid only if it has a non-zero value or same
as pid (of 0).

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20161206034010.6499-4-namhyung@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/builtin-sched.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 634d8cf..c8b3e6c 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -2118,7 +2118,9 @@ static struct thread *timehist_get_thread(struct perf_sched *sched,
 			pr_err("Failed to get idle thread for cpu %d.\n", sample->cpu);
 
 	} else {
-		thread = machine__findnew_thread(machine, sample->pid, sample->tid);
+		/* there were samples with tid 0 but non-zero pid */
+		thread = machine__findnew_thread(machine, sample->pid,
+						 sample->tid ?: sample->pid);
 		if (thread == NULL) {
 			pr_debug("Failed to get thread for tid %d. skipping sample.\n",
 				 sample->tid);