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authorDmitry Chagin <dchagin@FreeBSD.org>2021-07-29 09:43:07 +0000
committerDmitry Chagin <dchagin@FreeBSD.org>2021-07-29 09:43:07 +0000
commit8e4d22c01d8f76ae144f32b4c5fac40451429891 (patch)
tree99d5c2f1fdf5aa05f6426ae9ccb083688e6a10e6
parent7caa29115b4a2023128ed07942b71074507a44a1 (diff)
downloadsrc-8e4d22c01d8f76ae144f32b4c5fac40451429891.tar.gz
src-8e4d22c01d8f76ae144f32b4c5fac40451429891.zip
umtx: Add umtxq_requeue Linux emulation layer extension.
Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D31235 MFC after: 2 weeks
-rw-r--r--sys/kern/kern_umtx.c37
-rw-r--r--sys/sys/umtxvar.h1
2 files changed, 38 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)
{
diff --git a/sys/sys/umtxvar.h b/sys/sys/umtxvar.h
index de1b649ed8d7..ed2d8046a5fb 100644
--- a/sys/sys/umtxvar.h
+++ b/sys/sys/umtxvar.h
@@ -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 *);