Revert "selftests/mm: fix deadlock for fork after pthread_create on ARM"

Revert "selftests/mm: fix deadlock for fork after pthread_create on ARM"

Patch series "selftests/mm: revert pthread_barrier change"

On Android arm, pthread_create followed by a fork caused a deadlock in
the case where the fork required work to be completed by the created
thread.

The previous patches incorrectly assumed that the parent would
always initialize the pthread_barrier for the child thread.  This
reverts the change and replaces the fix for wp-fork-with-event with the
original use of atomic_bool.

This patch (of 3):

This reverts commit e142cc87ac4ec618f2ccf5f68aedcd6e28a59d9d.

fork_event_consumer may be called by other tests that do not initialize
the pthread_barrier, so this approach is not correct.  The subsequent
patch will revert to using atomic_bool instead.

Link: https://lkml.kernel.org/r/20241018171734.2315053-1-edliaw@google.com
Link: https://lkml.kernel.org/r/20241018171734.2315053-2-edliaw@google.com
Fixes: e142cc87ac4e ("fix deadlock for fork after pthread_create on ARM")
Signed-off-by: Edward Liaw <edliaw@google.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>