Commit 0146da0d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'locking_urgent_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull locking fix from Borislav Petkov:
 "Fix ordering in the queued writer lock's slowpath"

* tag 'locking_urgent_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/qrwlock: Fix ordering in queued_write_lock_slowpath()
parents 682b26bd 84a24bf8

kernel/locking/qrwlock.c

+4 −3
Original line number Diff line number Diff line
@@ -60,6 +60,8 @@ EXPORT_SYMBOL(queued_read_lock_slowpath); 
 */

void queued_write_lock_slowpath(struct qrwlock *lock)

{

	int cnts;



	/* Put the writer into the wait queue */

	arch_spin_lock(&lock->wait_lock);
@@ -73,9 +75,8 @@ void queued_write_lock_slowpath(struct qrwlock *lock) 


	/* When no more readers or writers, set the locked flag */

	do {

		atomic_cond_read_acquire(&lock->cnts, VAL == _QW_WAITING);

	} while (atomic_cmpxchg_relaxed(&lock->cnts, _QW_WAITING,

					_QW_LOCKED) != _QW_WAITING);

		cnts = atomic_cond_read_relaxed(&lock->cnts, VAL == _QW_WAITING);

	} while (!atomic_try_cmpxchg_acquire(&lock->cnts, &cnts, _QW_LOCKED));

unlock:

	arch_spin_unlock(&lock->wait_lock);

}