- Fix ordering in the queued writer lock's slowpath.

-----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmCFOD4ACgkQEsHwGGHe
 VUrwChAAr3r3Qr60WDUVTtbx0TS+d7Rk+aq63DhN6PvFADMlZe3PfjRFnw9bamIO
 hgf/65+BsYPTbO8w9CdSdgrv00oVw0v1pbYVdIAJDBzzwrG489gjJxozrIgQHU+X
 ixpxnG7R8e4dZrA4Q/ip2EZYRwGfWyO1H2Z1K6/W/sSk3HGi2EKa3+4BGBIhVtnI
 K81ckR59H+/+Fi8D3PZozK0HmC1XXKuoA5I0Yx0mgivy6i1XQ6UPohgWLXW76uae
 JtvbC2E9APhlYaRlIzdAAA7bx2REvyic6JjfTR515llIo3X2npVWlbusipjQdnOG
 enuFmHCCu49z9IAgGzI/ez+jEC41/SwJtma6lyDlcrW8j3Ovw5j6eMju14rrZD72
 8wqFXll7eAoFNbln0H9xUwvOVVWeIvMbF0+WluFWMsX5nDY4XRnEtYa24XPdeOFA
 aDhtuSmyQzcLi/mzgOU9q3dg/VKPb4i9XROwaXtJXXD8GVzbN2i5yOMleLmfHJ0K
 e1o/qc4VFItF+nCyp0v+yqEB8sQ23zRWiuw7zE1PvolBsULp+gO1lmJIJvSwaGaB
 nKJ04k7AvdkK82926cjfnhC6TvsOdHMWsdFBq+J/01bSnFGXwtzSJ6qoFTCts3TX
 zi7E5u+TEDAa4EZ4eO4Ds0yaKdJ0tBncoKUDLkTg7M98dLqv+dI=
 =GDTe
 -----END PGP SIGNATURE-----

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()
This commit is contained in:
Linus Torvalds 2021-04-25 09:10:10 -07:00
commit 0146da0d4c

View File

@ -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);
}