diff options
| -rw-r--r-- | sys/kern/kern_umtx.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c index 71287c4..135f7c7 100644 --- a/sys/kern/kern_umtx.c +++ b/sys/kern/kern_umtx.c @@ -2526,6 +2526,12 @@ do_rw_rdlock(struct thread *td, struct urwlock *rwlock, long fflag, int timo) umtxq_busy(&uq->uq_key); umtxq_unlock(&uq->uq_key); + /* + * re-read the state, in case it changed between the try-lock above + * and the check below + */ + state = fuword32(__DEVOLATILE(int32_t *, &rwlock->rw_state)); + /* set read contention bit */ while ((state & wrflags) && !(state & URWLOCK_READ_WAITERS)) { oldstate = casuword32(&rwlock->rw_state, state, state | URWLOCK_READ_WAITERS); @@ -2658,6 +2664,12 @@ do_rw_wrlock(struct thread *td, struct urwlock *rwlock, int timo) umtxq_busy(&uq->uq_key); umtxq_unlock(&uq->uq_key); + /* + * re-read the state, in case it changed between the try-lock above + * and the check below + */ + state = fuword32(__DEVOLATILE(int32_t *, &rwlock->rw_state)); + while (((state & URWLOCK_WRITE_OWNER) || URWLOCK_READER_COUNT(state) != 0) && (state & URWLOCK_WRITE_WAITERS) == 0) { oldstate = casuword32(&rwlock->rw_state, state, state | URWLOCK_WRITE_WAITERS); |
