diff options
Diffstat (limited to 'sys/kern/kern_umtx.c')
| -rw-r--r-- | sys/kern/kern_umtx.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c index d869d5870000..7c850c0d78d8 100644 --- a/sys/kern/kern_umtx.c +++ b/sys/kern/kern_umtx.c @@ -621,6 +621,43 @@ umtxq_signal_thread(struct umtx_q *uq) wakeup(uq); } +/* + * Wake up a maximum of n_wake threads that are waiting on an userland + * object identified by key. The remaining threads are removed from queue + * identified by key and added to the queue identified by key2 (requeued). + * The n_requeue specifies an upper limit on the number of threads that + * are requeued to the second queue. + */ +int +umtxq_requeue(struct umtx_key *key, int n_wake, struct umtx_key *key2, + int n_requeue) +{ + struct umtxq_queue *uh, *uh2; + struct umtx_q *uq, *uq_temp; + int ret; + + ret = 0; + UMTXQ_LOCKED_ASSERT(umtxq_getchain(key)); + UMTXQ_LOCKED_ASSERT(umtxq_getchain(key2)); + uh = umtxq_queue_lookup(key, UMTX_SHARED_QUEUE); + uh2 = umtxq_queue_lookup(key2, UMTX_SHARED_QUEUE); + if (uh == NULL) + return (0); + TAILQ_FOREACH_SAFE(uq, &uh->head, uq_link, uq_temp) { + if (++ret <= n_wake) { + umtxq_remove(uq); + wakeup_one(uq); + } else { + umtxq_remove(uq); + uq->uq_key = *key2; + umtxq_insert(uq); + if (ret - n_wake == n_requeue) + break; + } + } + return (ret); +} + static inline int tstohz(const struct timespec *tsp) { |