diff --git a/include/sys/taskq.h b/include/sys/taskq.h
index 4ea29cb3bb..54d869afec 100644
--- a/include/sys/taskq.h
+++ b/include/sys/taskq.h
@@ -51,8 +51,11 @@ typedef struct taskq_ent {
taskqid_t tqent_id;
task_func_t *tqent_func;
void *tqent_arg;
+ uintptr_t tqent_flags;
} taskq_ent_t;
+#define TQENT_FLAG_PREALLOC 0x1
+
/*
* Flags for taskq_dispatch. TQ_SLEEP/TQ_NOSLEEP should be same as
* KM_SLEEP/KM_NOSLEEP. TQ_NOQUEUE/TQ_NOALLOC are set particularly
@@ -100,6 +103,9 @@ typedef struct taskq_thread {
extern taskq_t *system_taskq;
extern taskqid_t __taskq_dispatch(taskq_t *, task_func_t, void *, uint_t);
+extern void __taskq_dispatch_ent(taskq_t *, task_func_t, void *, uint_t, taskq_ent_t *);
+extern int __taskq_empty_ent(taskq_ent_t *);
+extern void __taskq_init_ent(taskq_ent_t *);
extern taskq_t *__taskq_create(const char *, int, pri_t, int, int, uint_t);
extern void __taskq_destroy(taskq_t *);
extern void __taskq_wait_id(taskq_t *, taskqid_t);
@@ -113,6 +119,9 @@ void spl_taskq_fini(void);
#define taskq_wait_id(tq, id) __taskq_wait_id(tq, id)
#define taskq_wait(tq) __taskq_wait(tq)
#define taskq_dispatch(tq, f, p, fl) __taskq_dispatch(tq, f, p, fl)
+#define taskq_dispatch_ent(tq, f, p, fl, t) __taskq_dispatch_ent(tq, f, p, fl, t)
+#define taskq_empty_ent(t) __taskq_empty_ent(t)
+#define taskq_init_ent(t) __taskq_init_ent(t)
#define taskq_create(n, th, p, mi, ma, fl) __taskq_create(n, th, p, mi, ma, fl)
#define taskq_create_proc(n, th, p, mi, ma, pr, fl) \
__taskq_create(n, th, p, mi, ma, fl)
diff --git a/module/spl/spl-taskq.c b/module/spl/spl-taskq.c
index 5c22544b8b..b2b0e6ca86 100644
--- a/module/spl/spl-taskq.c
+++ b/module/spl/spl-taskq.c
@@ -57,6 +57,9 @@ retry:
/* Acquire taskq_ent_t's from free list if available */
if (!list_empty(&tq->tq_free_list) && !(flags & TQ_NEW)) {
t = list_entry(tq->tq_free_list.next, taskq_ent_t, tqent_list);
+
+ ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
+
list_del_init(&t->tqent_list);
SRETURN(t);
}
@@ -93,11 +96,7 @@ retry:
spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
if (t) {
- spin_lock_init(&t->tqent_lock);
- INIT_LIST_HEAD(&t->tqent_list);
- t->tqent_id = 0;
- t->tqent_func = NULL;
- t->tqent_arg = NULL;
+ taskq_init_ent(t);
tq->tq_nalloc++;
}
@@ -136,12 +135,18 @@ task_done(taskq_t *tq, taskq_ent_t *t)
ASSERT(t);
ASSERT(spin_is_locked(&tq->tq_lock));
+ /* For prealloc'd tasks, we don't free anything. */
+ if ((!(tq->tq_flags & TASKQ_DYNAMIC)) &&
+ (t->tqent_flags & TQENT_FLAG_PREALLOC))
+ return;
+
list_del_init(&t->tqent_list);
if (tq->tq_nalloc <= tq->tq_minalloc) {
t->tqent_id = 0;
t->tqent_func = NULL;
t->tqent_arg = NULL;
+ t->tqent_flags = 0;
list_add_tail(&t->tqent_list, &tq->tq_free_list);
} else {
task_free(tq, t);
@@ -281,6 +286,9 @@ __taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
tq->tq_next_id++;
t->tqent_func = func;
t->tqent_arg = arg;
+
+ ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
+
spin_unlock(&t->tqent_lock);
wake_up(&tq->tq_work_waitq);
@@ -289,6 +297,72 @@ out:
SRETURN(rc);
}
EXPORT_SYMBOL(__taskq_dispatch);
+
+void
+__taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
+ taskq_ent_t *t)
+{
+ SENTRY;
+
+ ASSERT(tq);
+ ASSERT(func);
+ ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC));
+
+ spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
+
+ /* Taskq being destroyed and all tasks drained */
+ if (!(tq->tq_flags & TQ_ACTIVE)) {
+ t->tqent_id = 0;
+ goto out;
+ }
+
+ spin_lock(&t->tqent_lock);
+
+ /*
+ * Mark it as a prealloc'd task. This is important
+ * to ensure that we don't free it later.
+ */
+ t->tqent_flags |= TQENT_FLAG_PREALLOC;
+
+ /* Queue to the priority list instead of the pending list */
+ if (flags & TQ_FRONT)
+ list_add_tail(&t->tqent_list, &tq->tq_prio_list);
+ else
+ list_add_tail(&t->tqent_list, &tq->tq_pend_list);
+
+ t->tqent_id = tq->tq_next_id;
+ tq->tq_next_id++;
+ t->tqent_func = func;
+ t->tqent_arg = arg;
+
+ spin_unlock(&t->tqent_lock);
+
+ wake_up(&tq->tq_work_waitq);
+out:
+ spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
+ SEXIT;
+}
+EXPORT_SYMBOL(__taskq_dispatch_ent);
+
+int
+__taskq_empty_ent(taskq_ent_t *t)
+{
+ return list_empty(&t->tqent_list);
+}
+EXPORT_SYMBOL(__taskq_empty_ent);
+
+void
+__taskq_init_ent(taskq_ent_t *t)
+{
+ spin_lock_init(&t->tqent_lock);
+ INIT_LIST_HEAD(&t->tqent_list);
+ t->tqent_id = 0;
+ t->tqent_func = NULL;
+ t->tqent_arg = NULL;
+ t->tqent_flags = 0;
+}
+EXPORT_SYMBOL(__taskq_init_ent);
+
/*
* Returns the lowest incomplete taskqid_t. The taskqid_t may
* be queued on the pending list, on the priority list, or on
@@ -407,6 +481,10 @@ taskq_thread(void *args)
if (pend_list) {
t = list_entry(pend_list->next, taskq_ent_t, tqent_list);
list_del_init(&t->tqent_list);
+ /* In order to support recursively dispatching a
+ * preallocated taskq_ent_t, tqent_id must be
+ * stored prior to executing tqent_func. */
+ id = t->tqent_id;
tqt->tqt_ent = t;
taskq_insert_in_order(tq, tqt);
tq->tq_nactive++;
@@ -419,7 +497,6 @@ taskq_thread(void *args)
tq->tq_nactive--;
list_del_init(&tqt->tqt_active_list);
tqt->tqt_ent = NULL;
- id = t->tqent_id;
task_done(tq, t);
/* When the current lowest outstanding taskqid is
@@ -570,6 +647,9 @@ __taskq_destroy(taskq_t *tq)
while (!list_empty(&tq->tq_free_list)) {
t = list_entry(tq->tq_free_list.next, taskq_ent_t, tqent_list);
+
+ ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
+
list_del_init(&t->tqent_list);
task_free(tq, t);
}