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umtx: Add umtxq_requeue Linux emulation layer extension.

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Reviewed by:		kib
Differential Revision:	https://reviews.freebsd.org/D31235
MFC after:		2 weeks
This commit is contained in:
Dmitry Chagin 2021-07-29 12:43:07 +03:00
parent 7caa29115b
commit 8e4d22c01d
2 changed files with 38 additions and 0 deletions
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37
sys/kern/kern_umtx.c
View File

@ -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)
{

1
sys/sys/umtxvar.h
View File

@ -210,6 +210,7 @@ void umtxq_free(struct umtx_q *);
struct umtxq_chain *umtxq_getchain(struct umtx_key *);
void umtxq_insert_queue(struct umtx_q *, int);
void umtxq_remove_queue(struct umtx_q *, int);
int umtxq_requeue(struct umtx_key *, int, struct umtx_key *, int);
int umtxq_signal_mask(struct umtx_key *, int, u_int);
int umtxq_sleep(struct umtx_q *, const char *,
struct umtx_abs_timeout *);