rwsem: shorter spinlocked section in rwsem_down_failed_common()

This change reduces the size of the spinlocked and TASK_UNINTERRUPTIBLE
sections in rwsem_down_failed_common():

- We only need the sem->wait_lock to insert ourselves on the wait_list;
  the waiter node can be prepared outside of the wait_lock.

- The task state only needs to be set to TASK_UNINTERRUPTIBLE immediately
  before checking if we actually need to sleep; it doesn't need to protect
  the entire function.

Signed-off-by: Michel Lespinasse <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Reviewed-by: Peter Hurley <[email protected]>
Acked-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions