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@suse.de>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/20210809043301.66002-7-dave@stgolabs.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/bench/futex-requeue.c b/tools/perf/bench/futex-requeue.c
index 6606569..e23a080 100644 (file)
--- a/tools/perf/bench/futex-requeue.c
+++ b/tools/perf/bench/futex-requeue.c
@@ -77,6 +77,8 @@ static void print_summary(void)
 
 static void *workerfn(void *arg __maybe_unused)
 {
+       int ret;
+
        pthread_mutex_lock(&thread_lock);
        threads_starting--;
        if (!threads_starting)
@@ -84,7 +86,18 @@ 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;
 }