diff options
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/qrwlock.c | 12 |
1 files changed, 4 insertions, 8 deletions
diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c index d9c36c5f5711..6a7a3b8d5ac9 100644 --- a/kernel/locking/qrwlock.c +++ b/kernel/locking/qrwlock.c @@ -88,15 +88,11 @@ void queued_read_lock_slowpath(struct qrwlock *lock, u32 cnts) arch_spin_lock(&lock->lock); /* - * At the head of the wait queue now, wait until the writer state - * goes to 0 and then try to increment the reader count and get - * the lock. It is possible that an incoming writer may steal the - * lock in the interim, so it is necessary to check the writer byte - * to make sure that the write lock isn't taken. + * At the head of the wait queue now, increment the reader count + * and wait until the writer, if it has the lock, has gone away. + * At ths stage, it is not possible for a writer to remain in the + * waiting state (_QW_WAITING). So there won't be any deadlock. */ - while (atomic_read(&lock->cnts) & _QW_WMASK) - cpu_relax_lowlatency(); - cnts = atomic_add_return(_QR_BIAS, &lock->cnts) - _QR_BIAS; rspin_until_writer_unlock(lock, cnts); |