libstdc++: Fix deadlock in shared_timed_mutex test [PR122401]HEADtrunkmaster

The test_shared_relative function deadlocks on older Glibc versions that
don't have pthread_rwlock_clockrdlock, because (as already mentioned
earlier in the test file) pthread_rwlock_timedrdlock returns EDEADLK if
the thread that already holds a write lock attempts to acquire read
lock, causing std::shared_timed_mutex to loop forever.

The fix is to do the invalid try_lock_shared_for call on a different
thread. To avoid undefined behaviour, we need to make the same changes
to all calls that try to acquire a lock that is already held.

Also add missing -pthread for PR122401.

libstdc++-v3/ChangeLog:

	PR libstdc++/122401
	* testsuite/30_threads/shared_timed_mutex/try_lock_until/116586.cc:
	Do not try to acquire locks on the thread that already holds a
	lock. Add -pthread for et pthread.

Reviewed-by: Mike Crowe <mac@mcrowe.com>
Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>

0 files changed, 0 insertions, 0 deletions