Introduce userspace condition variable, since we have already POSIX
priority mutex implemented, it is the time to introduce this stuff, now we can use umutex and ucond together to implement pthread's condition wait/signal.
This commit is contained in:
David Xu
parent
f2b93482b8
commit
a6abdf322d
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=164839
@ -955,7 +955,7 @@ do_wait(struct thread *td, void *addr, u_long id,
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umtxq_unlock(&uq->uq_key);
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} else if (timeout == NULL) {
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umtxq_lock(&uq->uq_key);
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error = umtxq_sleep(uq, "ucond", 0);
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error = umtxq_sleep(uq, "uwait", 0);
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umtxq_remove(uq);
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umtxq_unlock(&uq->uq_key);
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} else {
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@ -964,7 +964,7 @@ do_wait(struct thread *td, void *addr, u_long id,
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TIMESPEC_TO_TIMEVAL(&tv, timeout);
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umtxq_lock(&uq->uq_key);
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for (;;) {
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error = umtxq_sleep(uq, "ucond", tvtohz(&tv));
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error = umtxq_sleep(uq, "uwait", tvtohz(&tv));
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if (!(uq->uq_flags & UQF_UMTXQ))
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break;
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if (error != ETIMEDOUT)
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@ -2168,6 +2168,140 @@ do_unlock_umutex(struct thread *td, struct umutex *m)
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return (EINVAL);
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}
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static int
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do_cv_wait(struct thread *td, struct ucond *cv, struct umutex *m,
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struct timespec *timeout)
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{
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struct umtx_q *uq;
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struct timeval tv;
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struct timespec cts, ets, tts;
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uint32_t flags;
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int error;
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uq = td->td_umtxq;
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flags = fuword32(&cv->c_flags);
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error = umtx_key_get(cv, TYPE_CV, GET_SHARE(flags), &uq->uq_key);
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if (error != 0)
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return (error);
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umtxq_lock(&uq->uq_key);
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umtxq_busy(&uq->uq_key);
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umtxq_insert(uq);
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umtxq_unlock(&uq->uq_key);
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/*
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* The magic thing is we should set c_has_waiters to 1 before
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* releasing user mutex.
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*/
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suword32(__DEVOLATILE(uint32_t *, &cv->c_has_waiters), 1);
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umtxq_lock(&uq->uq_key);
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umtxq_unbusy(&uq->uq_key);
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umtxq_unlock(&uq->uq_key);
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error = do_unlock_umutex(td, m);
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umtxq_lock(&uq->uq_key);
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if (error == 0) {
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if (timeout == NULL) {
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error = umtxq_sleep(uq, "ucond", 0);
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} else {
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getnanouptime(&ets);
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timespecadd(&ets, timeout);
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TIMESPEC_TO_TIMEVAL(&tv, timeout);
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for (;;) {
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error = umtxq_sleep(uq, "ucond", tvtohz(&tv));
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if (error != ETIMEDOUT)
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break;
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getnanouptime(&cts);
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if (timespeccmp(&cts, &ets, >=)) {
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error = ETIMEDOUT;
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break;
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}
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tts = ets;
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timespecsub(&tts, &cts);
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TIMESPEC_TO_TIMEVAL(&tv, &tts);
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}
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}
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}
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if (error != 0) {
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if ((uq->uq_flags & UQF_UMTXQ) == 0) {
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/*
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* If we concurrently got do_cv_signal()d
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* and we got an error or UNIX signals or a timeout,
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* then, perform another umtxq_signal to avoid
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* consuming the wakeup. This may cause supurious
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* wakeup for another thread which was just queued,
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* but SUSV3 explicitly allows supurious wakeup to
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* occur, and indeed a kernel based implementation
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* can not avoid it.
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*/
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umtxq_signal(&uq->uq_key, 1);
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}
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if (error == ERESTART)
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error = EINTR;
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}
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umtxq_remove(uq);
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umtxq_unlock(&uq->uq_key);
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umtx_key_release(&uq->uq_key);
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return (error);
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}
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/*
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* Signal a userland condition variable.
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*/
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static int
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do_cv_signal(struct thread *td, struct ucond *cv)
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{
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struct umtx_key key;
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int error, cnt, nwake;
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uint32_t flags;
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flags = fuword32(&cv->c_flags);
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if ((error = umtx_key_get(cv, TYPE_CV, GET_SHARE(flags), &key)) != 0)
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return (error);
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umtxq_lock(&key);
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umtxq_busy(&key);
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cnt = umtxq_count(&key);
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nwake = umtxq_signal(&key, 1);
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if (cnt <= nwake) {
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umtxq_unlock(&key);
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error = suword32(
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__DEVOLATILE(uint32_t *, &cv->c_has_waiters), 0);
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umtxq_lock(&key);
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}
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umtxq_unbusy(&key);
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umtxq_unlock(&key);
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umtx_key_release(&key);
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return (error);
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}
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static int
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do_cv_broadcast(struct thread *td, struct ucond *cv)
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{
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struct umtx_key key;
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int error;
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uint32_t flags;
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flags = fuword32(&cv->c_flags);
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if ((error = umtx_key_get(cv, TYPE_CV, GET_SHARE(flags), &key)) != 0)
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return (error);
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umtxq_lock(&key);
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umtxq_busy(&key);
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umtxq_signal(&key, INT_MAX);
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umtxq_unlock(&key);
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error = suword32(__DEVOLATILE(uint32_t *, &cv->c_has_waiters), 0);
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umtxq_lock(&key);
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umtxq_unbusy(&key);
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umtxq_unlock(&key);
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umtx_key_release(&key);
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return (error);
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}
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int
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_umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
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/* struct umtx *umtx */
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@ -2277,6 +2411,41 @@ __umtx_op_set_ceiling(struct thread *td, struct _umtx_op_args *uap)
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return do_set_ceiling(td, uap->obj, uap->val, uap->uaddr1);
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}
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static int
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__umtx_op_cv_wait(struct thread *td, struct _umtx_op_args *uap)
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{
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struct timespec *ts, timeout;
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int error;
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/* Allow a null timespec (wait forever). */
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if (uap->uaddr2 == NULL)
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ts = NULL;
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else {
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error = copyin(uap->uaddr2, &timeout,
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sizeof(timeout));
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if (error != 0)
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return (error);
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if (timeout.tv_nsec >= 1000000000 ||
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timeout.tv_nsec < 0) {
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return (EINVAL);
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}
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ts = &timeout;
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}
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return (do_cv_wait(td, uap->obj, uap->uaddr1, ts));
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}
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static int
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__umtx_op_cv_signal(struct thread *td, struct _umtx_op_args *uap)
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{
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return do_cv_signal(td, uap->obj);
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}
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static int
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__umtx_op_cv_broadcast(struct thread *td, struct _umtx_op_args *uap)
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{
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return do_cv_broadcast(td, uap->obj);
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}
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typedef int (*_umtx_op_func)(struct thread *td, struct _umtx_op_args *uap);
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static _umtx_op_func op_table[] = {
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@ -2287,7 +2456,10 @@ static _umtx_op_func op_table[] = {
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__umtx_op_trylock_umutex, /* UMTX_OP_MUTEX_TRYLOCK */
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__umtx_op_lock_umutex, /* UMTX_OP_MUTEX_LOCK */
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__umtx_op_unlock_umutex, /* UMTX_OP_MUTEX_UNLOCK */
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__umtx_op_set_ceiling /* UMTX_OP_SET_CEILING */
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__umtx_op_set_ceiling, /* UMTX_OP_SET_CEILING */
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__umtx_op_cv_wait, /* UMTX_OP_CV_WAIT*/
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__umtx_op_cv_signal, /* UMTX_OP_CV_SIGNAL */
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__umtx_op_cv_broadcast /* UMTX_OP_CV_BROADCAST */
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};
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int
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@ -2402,6 +2574,27 @@ __umtx_op_lock_umutex_compat32(struct thread *td, struct _umtx_op_args *uap)
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return do_lock_umutex(td, uap->obj, ts, 0);
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}
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static int
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__umtx_op_cv_wait_compat32(struct thread *td, struct _umtx_op_args *uap)
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{
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struct timespec *ts, timeout;
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int error;
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/* Allow a null timespec (wait forever). */
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if (uap->uaddr2 == NULL)
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ts = NULL;
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else {
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error = copyin_timeout32(uap->uaddr2, &timeout);
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if (error != 0)
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return (error);
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if (timeout.tv_nsec >= 1000000000 ||
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timeout.tv_nsec < 0)
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return (EINVAL);
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ts = &timeout;
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}
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return (do_cv_wait(td, uap->obj, uap->uaddr1, ts));
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}
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static _umtx_op_func op_table_compat32[] = {
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__umtx_op_lock_umtx_compat32, /* UMTX_OP_LOCK */
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__umtx_op_unlock_umtx_compat32, /* UMTX_OP_UNLOCK */
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@ -2410,7 +2603,10 @@ static _umtx_op_func op_table_compat32[] = {
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__umtx_op_trylock_umutex, /* UMTX_OP_MUTEX_LOCK */
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__umtx_op_lock_umutex_compat32, /* UMTX_OP_MUTEX_TRYLOCK */
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__umtx_op_unlock_umutex, /* UMTX_OP_MUTEX_UNLOCK */
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__umtx_op_set_ceiling /* UMTX_OP_SET_CEILING */
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__umtx_op_set_ceiling, /* UMTX_OP_SET_CEILING */
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__umtx_op_cv_wait_compat32, /* UMTX_OP_CV_WAIT*/
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__umtx_op_cv_signal, /* UMTX_OP_CV_SIGNAL */
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__umtx_op_cv_broadcast /* UMTX_OP_CV_BROADCAST */
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};
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int
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@ -49,26 +49,36 @@ struct umtx {
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#define UMUTEX_UNOWNED 0x0
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#define UMUTEX_CONTESTED 0x80000000U
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#define UMUTEX_ERROR_CHECK 0x0002 /* Error-checking mutex */
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#define UMUTEX_PRIO_INHERIT 0x0004 /* Priority inherited mutex */
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#define UMUTEX_PRIO_PROTECT 0x0008 /* Priority protect mutex */
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#define UMUTEX_ERROR_CHECK 0x0002 /* Error-checking mutex */
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#define UMUTEX_PRIO_INHERIT 0x0004 /* Priority inherited mutex */
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#define UMUTEX_PRIO_PROTECT 0x0008 /* Priority protect mutex */
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struct umutex {
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volatile __lwpid_t m_owner; /* Owner of the mutex */
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uint32_t m_flags; /* Flags of the mutex */
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uint32_t m_ceilings[2]; /* Priority protect ceiling */
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uint32_t m_spare[4]; /* Spare space */
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uint32_t m_flags; /* Flags of the mutex */
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uint32_t m_ceilings[2]; /* Priority protect ceiling */
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uint32_t m_spare[4]; /* Spare space */
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};
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struct ucond {
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volatile uint32_t c_has_waiters; /* Has waiters in kernel */
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uint32_t c_flags; /* Flags of the condition variable */
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uint32_t c_spare[2]; /* Spare space */
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};
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/* op code for _umtx_op */
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#define UMTX_OP_LOCK 0
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#define UMTX_OP_UNLOCK 1
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#define UMTX_OP_WAIT 2
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#define UMTX_OP_WAKE 3
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#define UMTX_OP_MUTEX_TRYLOCK 4
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#define UMTX_OP_MUTEX_LOCK 5
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#define UMTX_OP_MUTEX_UNLOCK 6
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#define UMTX_OP_SET_CEILING 7
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#define UMTX_OP_MAX 8
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#define UMTX_OP_LOCK 0
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#define UMTX_OP_UNLOCK 1
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#define UMTX_OP_WAIT 2
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#define UMTX_OP_WAKE 3
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#define UMTX_OP_MUTEX_TRYLOCK 4
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#define UMTX_OP_MUTEX_LOCK 5
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#define UMTX_OP_MUTEX_UNLOCK 6
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#define UMTX_OP_SET_CEILING 7
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#define UMTX_OP_CV_WAIT 8
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#define UMTX_OP_CV_SIGNAL 9
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#define UMTX_OP_CV_BROADCAST 10
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#define UMTX_OP_MAX 11
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#ifndef _KERNEL
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