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[PATCH] [testsuite][racy] Fix race condition in check-libthread-db
- From: Alan Hayward <alan dot hayward at arm dot com>
- To: gdb-patches at sourceware dot org
- Cc: nd at arm dot com, Alan Hayward <alan dot hayward at arm dot com>
- Date: Wed, 26 Sep 2018 16:00:35 +0100
- Subject: [PATCH] [testsuite][racy] Fix race condition in check-libthread-db
It is possible for the created thread to reach the breakpoint before
the main thread has set errno to 23.
Prevent this using a pthread barrier.
gdb/testsuite/ChangeLog:
2018-09-26 Alan Hayward <alan.hayward@arm.com>
* gdb.threads/check-libthread-db.c (thread_routine): Use a
pthread barrier.
(main): Likewise.
---
gdb/testsuite/gdb.threads/check-libthread-db.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/gdb/testsuite/gdb.threads/check-libthread-db.c b/gdb/testsuite/gdb.threads/check-libthread-db.c
index 85a97a93af..39d39694ce 100644
--- a/gdb/testsuite/gdb.threads/check-libthread-db.c
+++ b/gdb/testsuite/gdb.threads/check-libthread-db.c
@@ -23,6 +23,10 @@
#include <pthread.h>
#include <errno.h>
+/* This barrier ensures we only reach the initial breakpoint both threads have
+ set errno. */
+pthread_barrier_t start_threads_barrier;
+
static void
break_here (void)
{
@@ -32,6 +36,7 @@ static void *
thread_routine (void *arg)
{
errno = 42;
+ pthread_barrier_wait (&start_threads_barrier);
break_here ();
@@ -47,6 +52,8 @@ main (int argc, char *argv)
pthread_t the_thread;
int err;
+ pthread_barrier_init (&start_threads_barrier, NULL, 2);
+
err = pthread_create (&the_thread, NULL, thread_routine, NULL);
if (err != 0)
{
@@ -55,6 +62,7 @@ main (int argc, char *argv)
}
errno = 23;
+ pthread_barrier_wait (&start_threads_barrier);
err = pthread_join (the_thread, NULL);
if (err != 0)
--
2.15.2 (Apple Git-101.1)