percpu-rwsem: cleanup the lockdep annotations in percpu_down_read()

Stolen from Peter's patch.

Change percpu_down_read() to use __down_read(), this way we can
do rwsem_acquire_read() unconditionally at the start to make this
code more symmetric and clean.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
1 file changed