From 9fc3183f0f8ab8ec85f0e5f65bae9e18ddf545a0 Mon Sep 17 00:00:00 2001 From: Alan Hayward Date: Wed, 26 Sep 2018 14:06:54 +0100 Subject: [PATCH] testsuite: 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.threads/check-libthread-db.c (thread_routine): Use a pthread barrier. (main): Likewise. --- gdb/testsuite/ChangeLog | 6 ++++++ gdb/testsuite/gdb.threads/check-libthread-db.c | 8 ++++++++ 2 files changed, 14 insertions(+) diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 2b4b0973ef2..2072705fd53 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2018-09-27 Alan Hayward + + * gdb.threads/check-libthread-db.c (thread_routine): Use a + pthread barrier. + (main): Likewise. + 2018-09-26 Andrew Burgess * gdb.base/large-frame-1.c: New file. diff --git a/gdb/testsuite/gdb.threads/check-libthread-db.c b/gdb/testsuite/gdb.threads/check-libthread-db.c index 85a97a93af9..2d9aec4bb44 100644 --- a/gdb/testsuite/gdb.threads/check-libthread-db.c +++ b/gdb/testsuite/gdb.threads/check-libthread-db.c @@ -23,6 +23,10 @@ #include #include +/* This barrier ensures we only reach the initial breakpoint after 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) -- 2.30.2