linux-kernel - [PATCH] perf: ignore exited thread when synthesize thread map

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Date:   Wed, 22 Nov 2023 10:21:54 +0800
From:   Cruz Zhao <CruzZhao@...ux.alibaba.com>
To:     mingo@...hat.com, peterz@...radead.org, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        jolsa@...nel.org, namhyung@...nel.org, irogers@...gle.com,
        adrian.hunter@...el.com, kprateek.nayak@....com
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] perf: ignore exited thread when synthesize thread map

When synthesize thread map, some threads in thread map may have
already exited, so that __event__synthesize_thread() returns -1
and the synthesis breaks. However, It will not have any effect
if we just ignore the exited thread. So just ignore it and continue.

Signed-off-by: Cruz Zhao <CruzZhao@...ux.alibaba.com>
---
 tools/perf/util/synthetic-events.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index a0579c7d7b9e..43ad2298a933 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -866,14 +866,16 @@ int perf_event__synthesize_thread_map(struct perf_tool *tool,
 
 	err = 0;
 	for (thread = 0; thread < threads->nr; ++thread) {
+		/*
+		 * We may race with exiting thread, so don't stop just because
+		 * one thread couldn't be synthesized.
+		 */
 		if (__event__synthesize_thread(comm_event, mmap_event,
 					       fork_event, namespaces_event,
 					       perf_thread_map__pid(threads, thread), 0,
 					       process, tool, machine,
-					       needs_mmap, mmap_data)) {
-			err = -1;
-			break;
-		}
+					       needs_mmap, mmap_data))
+			continue;
 
 		/*
 		 * comm.pid is set to thread group id by
-- 
2.39.3