diff options
| author | Tim Chase <[email protected]> | 2015-08-27 11:13:20 -0500 |
|---|---|---|
| committer | Brian Behlendorf <[email protected]> | 2015-09-01 08:46:41 -0700 |
| commit | a64e55752f4e88dcb544f2480100dcd6f6be3277 (patch) | |
| tree | c2e2a190ec0331ff1c154fd0eb0e04d6206850fc | |
| parent | 801b56090b42763d1d3b2593bb8d731d0d8fef22 (diff) | |
Create a new thread during recursive taskq dispatch if necessary
When dynamic taskq is enabled and all threads for a taskq are occupied,
a recursive dispatch can cause a deadlock if calling thread depends on
the recursively-dispatched thread for its return condition.
This patch attempts to create a new thread for recursive dispatch when
none are available.
Signed-off-by: Tim Chase <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #472
| -rw-r--r-- | module/spl/spl-taskq.c | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/module/spl/spl-taskq.c b/module/spl/spl-taskq.c index 7a756af37..82e71a388 100644 --- a/module/spl/spl-taskq.c +++ b/module/spl/spl-taskq.c @@ -448,8 +448,8 @@ taskq_wait(taskq_t *tq) } EXPORT_SYMBOL(taskq_wait); -int -taskq_member(taskq_t *tq, void *t) +static int +taskq_member_impl(taskq_t *tq, void *t) { struct list_head *l; taskq_thread_t *tqt; @@ -457,8 +457,8 @@ taskq_member(taskq_t *tq, void *t) ASSERT(tq); ASSERT(t); + ASSERT(spin_is_locked(&tq->tq_lock)); - spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags); list_for_each(l, &tq->tq_thread_list) { tqt = list_entry(l, taskq_thread_t, tqt_thread_list); if (tqt->tqt_thread == (struct task_struct *)t) { @@ -466,6 +466,16 @@ taskq_member(taskq_t *tq, void *t) break; } } + return (found); +} + +int +taskq_member(taskq_t *tq, void *t) +{ + int found; + + spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags); + found = taskq_member_impl(tq, t); spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags); return (found); @@ -528,6 +538,8 @@ taskq_cancel_id(taskq_t *tq, taskqid_t id) } EXPORT_SYMBOL(taskq_cancel_id); +static int taskq_thread_spawn(taskq_t *tq, int seq_tasks); + taskqid_t taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags) { @@ -574,6 +586,11 @@ taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags) wake_up(&tq->tq_work_waitq); out: + /* Spawn additional taskq threads if required. */ + if (tq->tq_nactive == tq->tq_nthreads && + taskq_member_impl(tq, current)) + (void) taskq_thread_spawn(tq, spl_taskq_thread_sequential + 1); + spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags); return (rc); } @@ -617,6 +634,10 @@ taskq_dispatch_delay(taskq_t *tq, task_func_t func, void *arg, spin_unlock(&t->tqent_lock); out: + /* Spawn additional taskq threads if required. */ + if (tq->tq_nactive == tq->tq_nthreads && + taskq_member_impl(tq, current)) + (void) taskq_thread_spawn(tq, spl_taskq_thread_sequential + 1); spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags); return (rc); } @@ -661,6 +682,10 @@ taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags, wake_up(&tq->tq_work_waitq); out: + /* Spawn additional taskq threads if required. */ + if (tq->tq_nactive == tq->tq_nthreads && + taskq_member_impl(tq, current)) + (void) taskq_thread_spawn(tq, spl_taskq_thread_sequential + 1); spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags); } EXPORT_SYMBOL(taskq_dispatch_ent); |