linux-kernel - [PATCH 6/7] perf/bench-futex, requeue: Robustify futex

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Message-Id: <20210809043301.66002-7-dave@stgolabs.net>
Date:   Sun,  8 Aug 2021 21:33:00 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     acme@...nel.org
Cc:     mingo@...hat.com, peterz@...radead.org, tglx@...utronix.de,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        dave@...olabs.net, Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 6/7] perf/bench-futex, requeue: Robustify futex_wait() handling

Do not assume success and account for EAGAIN or any other return value,
however unlikely.

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 tools/perf/bench/futex-requeue.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/tools/perf/bench/futex-requeue.c b/tools/perf/bench/futex-requeue.c
index 80f40ee92b53..e4892ba6864f 100644
--- a/tools/perf/bench/futex-requeue.c
+++ b/tools/perf/bench/futex-requeue.c
@@ -76,6 +76,8 @@ static void print_summary(void)
 
 static void *workerfn(void *arg __maybe_unused)
 {
+	int ret;
+
 	pthread_mutex_lock(&thread_lock);
 	threads_starting--;
 	if (!threads_starting)
@@ -83,7 +85,18 @@ static void *workerfn(void *arg __maybe_unused)
 	pthread_cond_wait(&thread_worker, &thread_lock);
 	pthread_mutex_unlock(&thread_lock);
 
-	futex_wait(&futex1, 0, NULL, futex_flag);
+	while (1) {
+		ret = futex_wait(&futex1, 0, NULL, futex_flag);
+		if (!ret)
+			break;
+
+		if (ret && errno != EAGAIN) {
+			if (!params.silent)
+				warn("futex_wait");
+			break;
+		}
+	}
+
 	return NULL;
 }
 
-- 
2.26.2