#define DEBUG_SUBSYSTEM S_TASKQ
-/*
- * Task queue interface
- *
- * The taskq_work_wrapper functions are used to manage the work_structs
- * which must be submitted to linux. The shim layer allocates a wrapper
- * structure for all items which contains a pointer to itself as well as
- * the real work to be performed. When the work item run the generic
- * handle is called which calls the real work function and then using
- * the self pointer frees the work_struct.
+/* NOTE: Must be called with tq->tq_lock held, returns a list_t which
+ * is not attached to the free, work, or pending taskq lists.
*/
-typedef struct taskq_work_wrapper {
- struct work_struct tww_work;
- task_func_t tww_func;
- void * tww_priv;
-} taskq_work_wrapper_t;
+static task_t *
+task_alloc(taskq_t *tq, uint_t flags)
+{
+ task_t *t;
+ int count = 0;
+ ENTRY;
+
+ ASSERT(tq);
+ ASSERT(flags & (TQ_SLEEP | TQ_NOSLEEP)); /* One set */
+ ASSERT(!((flags & TQ_SLEEP) && (flags & TQ_NOSLEEP))); /* Not both */
+ ASSERT(spin_is_locked(&tq->tq_lock));
+retry:
+ /* Aquire task_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, task_t, t_list);
+ list_del_init(&t->t_list);
+ RETURN(t);
+ }
+
+ /* Free list is empty and memory allocs are prohibited */
+ if (flags & TQ_NOALLOC)
+ RETURN(NULL);
+
+ /* Hit maximum task_t pool size */
+ if (tq->tq_nalloc >= tq->tq_maxalloc) {
+ if (flags & TQ_NOSLEEP)
+ RETURN(NULL);
+
+ /* Sleep periodically polling the free list for an available
+ * task_t. If a full second passes and we have not found
+ * one gives up and return a NULL to the caller. */
+ if (flags & TQ_SLEEP) {
+ spin_unlock_irq(&tq->tq_lock);
+ schedule_timeout(HZ / 100);
+ spin_lock_irq(&tq->tq_lock);
+ if (count < 100)
+ GOTO(retry, count++);
+
+ RETURN(NULL);
+ }
+
+ /* Unreachable, TQ_SLEEP xor TQ_NOSLEEP */
+ SBUG();
+ }
+
+ spin_unlock_irq(&tq->tq_lock);
+ t = kmem_alloc(sizeof(task_t), flags & (TQ_SLEEP | TQ_NOSLEEP));
+ spin_lock_irq(&tq->tq_lock);
+
+ if (t) {
+ spin_lock_init(&t->t_lock);
+ INIT_LIST_HEAD(&t->t_list);
+ t->t_id = 0;
+ t->t_func = NULL;
+ t->t_arg = NULL;
+ tq->tq_nalloc++;
+ }
+
+ RETURN(t);
+}
+
+/* NOTE: Must be called with tq->tq_lock held, expectes the task_t
+ * to already be removed from the free, work, or pending taskq lists.
+ */
+static void
+task_free(taskq_t *tq, task_t *t)
+{
+ ENTRY;
+
+ ASSERT(tq);
+ ASSERT(t);
+ ASSERT(spin_is_locked(&tq->tq_lock));
+ ASSERT(list_empty(&t->t_list));
+
+ kmem_free(t, sizeof(task_t));
+ tq->tq_nalloc--;
+ EXIT;
+}
+
+/* NOTE: Must be called with tq->tq_lock held, either destroyes the
+ * task_t if too many exist or moves it to the free list for later use.
+ */
static void
-taskq_work_handler(void *priv)
+task_done(taskq_t *tq, task_t *t)
{
- taskq_work_wrapper_t *tww = priv;
+ ENTRY;
+ ASSERT(tq);
+ ASSERT(t);
+ ASSERT(spin_is_locked(&tq->tq_lock));
+
+ list_del_init(&t->t_list);
- ASSERT(tww);
- ASSERT(tww->tww_func);
+ if (tq->tq_nalloc <= tq->tq_minalloc) {
+ t->t_id = 0;
+ t->t_func = NULL;
+ t->t_arg = NULL;
+ list_add(&t->t_list, &tq->tq_free_list);
+ } else {
+ task_free(tq, t);
+ }
- /* Call the real function and free the wrapper */
- tww->tww_func(tww->tww_priv);
- kfree(tww);
+ EXIT;
}
-/* XXX - All flags currently ignored */
-taskqid_t
-__taskq_dispatch(taskq_t *tq, task_func_t func, void *priv, uint_t flags)
+/* Taskqid's are handed out in a monotonically increasing fashion per
+ * taskq_t. We don't handle taskqid wrapping yet, but fortuntely it isi
+ * a 64-bit value so this is probably never going to happen. The lowest
+ * pending taskqid is stored in the taskq_t to make it easy for any
+ * taskq_wait()'ers to know if the tasks they're waiting for have
+ * completed. Unfortunately, tq_task_lowest is kept up to date is
+ * a pretty brain dead way, something more clever should be done.
+ */
+static int
+taskq_wait_check(taskq_t *tq, taskqid_t id)
+{
+ RETURN(tq->tq_lowest_id >= id);
+}
+
+/* Expected to wait for all previously scheduled tasks to complete. We do
+ * not need to wait for tasked scheduled after this call to complete. In
+ * otherwords we do not need to drain the entire taskq. */
+void
+__taskq_wait_id(taskq_t *tq, taskqid_t id)
{
- struct workqueue_struct *wq = tq;
- taskq_work_wrapper_t *tww;
- int rc;
ENTRY;
+ ASSERT(tq);
+
+ wait_event(tq->tq_wait_waitq, taskq_wait_check(tq, id));
+
+ EXIT;
+}
+EXPORT_SYMBOL(__taskq_wait_id);
+
+void
+__taskq_wait(taskq_t *tq)
+{
+ taskqid_t id;
+ ENTRY;
+ ASSERT(tq);
+
+ spin_lock_irq(&tq->tq_lock);
+ id = tq->tq_next_id;
+ spin_unlock_irq(&tq->tq_lock);
+
+ __taskq_wait_id(tq, id);
+
+ EXIT;
+
+}
+EXPORT_SYMBOL(__taskq_wait);
+
+int
+__taskq_member(taskq_t *tq, void *t)
+{
+ int i;
+ ENTRY;
+
+ ASSERT(tq);
+ ASSERT(t);
+
+ for (i = 0; i < tq->tq_nthreads; i++)
+ if (tq->tq_threads[i] == (struct task_struct *)t)
+ RETURN(1);
+
+ RETURN(0);
+}
+EXPORT_SYMBOL(__taskq_member);
+
+taskqid_t
+__taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
+{
+ task_t *t;
+ taskqid_t rc = 0;
+ ENTRY;
ASSERT(tq);
ASSERT(func);
+ if (unlikely(in_atomic() && (flags & TQ_SLEEP))) {
+ CERROR("May schedule while atomic: %s/0x%08x/%d\n",
+ current->comm, preempt_count(), current->pid);
+ SBUG();
+ }
- /* Use GFP_ATOMIC since this may be called in interrupt context */
- tww = (taskq_work_wrapper_t *)kmalloc(sizeof(*tww), GFP_ATOMIC);
- if (!tww)
- RETURN((taskqid_t)0);
+ spin_lock_irq(&tq->tq_lock);
- INIT_WORK(&(tww->tww_work), taskq_work_handler, tww);
- tww->tww_func = func;
- tww->tww_priv = priv;
+ /* Taskq being destroyed and all tasks drained */
+ if (!(tq->tq_flags & TQ_ACTIVE))
+ GOTO(out, rc = 0);
- rc = queue_work(wq, &(tww->tww_work));
- if (!rc) {
- kfree(tww);
- RETURN((taskqid_t)0);
- }
+ /* Do not queue the task unless there is idle thread for it */
+ ASSERT(tq->tq_nactive <= tq->tq_nthreads);
+ if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads))
+ GOTO(out, rc = 0);
+
+ if ((t = task_alloc(tq, flags)) == NULL)
+ GOTO(out, rc = 0);
- RETURN((taskqid_t)wq);
+
+ spin_lock(&t->t_lock);
+ list_add(&t->t_list, &tq->tq_pend_list);
+ t->t_id = rc = tq->tq_next_id;
+ tq->tq_next_id++;
+ t->t_func = func;
+ t->t_arg = arg;
+ spin_unlock(&t->t_lock);
+
+ wake_up(&tq->tq_work_waitq);
+out:
+ spin_unlock_irq(&tq->tq_lock);
+ RETURN(rc);
}
EXPORT_SYMBOL(__taskq_dispatch);
-/* XXX - We must fully implement dynamic workqueues since they make a
- * significant impact in terms of performance. For now I've made
- * a trivial compromise. If you ask for one thread you get one
- * thread, if you ask for more than that you get one per core.
- * It's unclear if you ever really need/want more than one per-core
- * anyway. More analysis is required.
- *
- * name - Workqueue names are limited to 10 chars
- * pri - Ignore priority
- * min - Ignored until this is a dynamic thread pool
- * max - Ignored until this is a dynamic thread pool
- * flags - Ignored until this is a dynamic thread_pool
- */
+/* NOTE: Must be called with tq->tq_lock held */
+static taskqid_t
+taskq_lowest_id(taskq_t *tq)
+{
+ taskqid_t lowest_id = ~0;
+ task_t *t;
+ ENTRY;
+
+ ASSERT(tq);
+ ASSERT(spin_is_locked(&tq->tq_lock));
+
+ list_for_each_entry(t, &tq->tq_pend_list, t_list)
+ if (t->t_id < lowest_id)
+ lowest_id = t->t_id;
+
+ list_for_each_entry(t, &tq->tq_work_list, t_list)
+ if (t->t_id < lowest_id)
+ lowest_id = t->t_id;
+
+ RETURN(lowest_id);
+}
+
+static int
+taskq_thread(void *args)
+{
+ DECLARE_WAITQUEUE(wait, current);
+ sigset_t blocked;
+ taskqid_t id;
+ taskq_t *tq = args;
+ task_t *t;
+ ENTRY;
+
+ ASSERT(tq);
+ current->flags |= PF_NOFREEZE;
+
+ sigfillset(&blocked);
+ sigprocmask(SIG_BLOCK, &blocked, NULL);
+ flush_signals(current);
+
+ spin_lock_irq(&tq->tq_lock);
+ tq->tq_nthreads++;
+ wake_up(&tq->tq_wait_waitq);
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ while (!kthread_should_stop()) {
+
+ add_wait_queue(&tq->tq_work_waitq, &wait);
+ if (list_empty(&tq->tq_pend_list)) {
+ spin_unlock_irq(&tq->tq_lock);
+ schedule();
+ spin_lock_irq(&tq->tq_lock);
+ } else {
+ __set_current_state(TASK_RUNNING);
+ }
+
+ remove_wait_queue(&tq->tq_work_waitq, &wait);
+ if (!list_empty(&tq->tq_pend_list)) {
+ t = list_entry(tq->tq_pend_list.next, task_t, t_list);
+ list_del_init(&t->t_list);
+ list_add(&t->t_list, &tq->tq_work_list);
+ tq->tq_nactive++;
+ spin_unlock_irq(&tq->tq_lock);
+
+ /* Perform the requested task */
+ t->t_func(t->t_arg);
+
+ spin_lock_irq(&tq->tq_lock);
+ tq->tq_nactive--;
+ id = t->t_id;
+ task_done(tq, t);
+
+ /* Update the lowest remaining taskqid yet to run */
+ if (tq->tq_lowest_id == id) {
+ tq->tq_lowest_id = taskq_lowest_id(tq);
+ ASSERT(tq->tq_lowest_id > id);
+ }
+
+ wake_up_all(&tq->tq_wait_waitq);
+ }
+
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ }
+
+ __set_current_state(TASK_RUNNING);
+ tq->tq_nthreads--;
+ spin_unlock_irq(&tq->tq_lock);
+
+ RETURN(0);
+}
+
taskq_t *
__taskq_create(const char *name, int nthreads, pri_t pri,
int minalloc, int maxalloc, uint_t flags)
{
- taskq_t *tq;
- ENTRY;
+ taskq_t *tq;
+ struct task_struct *t;
+ int rc = 0, i, j = 0;
+ ENTRY;
+
+ ASSERT(name != NULL);
+ ASSERT(pri <= maxclsyspri);
+ ASSERT(minalloc >= 0);
+ ASSERT(maxalloc <= INT_MAX);
+ ASSERT(!(flags & (TASKQ_CPR_SAFE | TASKQ_DYNAMIC))); /* Unsupported */
+
+ tq = kmem_alloc(sizeof(*tq), KM_SLEEP);
+ if (tq == NULL)
+ RETURN(NULL);
+
+ tq->tq_threads = kmem_alloc(nthreads * sizeof(t), KM_SLEEP);
+ if (tq->tq_threads == NULL) {
+ kmem_free(tq, sizeof(*tq));
+ RETURN(NULL);
+ }
+
+ spin_lock_init(&tq->tq_lock);
+ spin_lock_irq(&tq->tq_lock);
+ tq->tq_name = name;
+ tq->tq_nactive = 0;
+ tq->tq_nthreads = 0;
+ tq->tq_pri = pri;
+ tq->tq_minalloc = minalloc;
+ tq->tq_maxalloc = maxalloc;
+ tq->tq_nalloc = 0;
+ tq->tq_flags = (flags | TQ_ACTIVE);
+ tq->tq_next_id = 1;
+ tq->tq_lowest_id = 1;
+ INIT_LIST_HEAD(&tq->tq_free_list);
+ INIT_LIST_HEAD(&tq->tq_work_list);
+ INIT_LIST_HEAD(&tq->tq_pend_list);
+ init_waitqueue_head(&tq->tq_work_waitq);
+ init_waitqueue_head(&tq->tq_wait_waitq);
+
+ if (flags & TASKQ_PREPOPULATE)
+ for (i = 0; i < minalloc; i++)
+ task_done(tq, task_alloc(tq, TQ_SLEEP | TQ_NEW));
- if (nthreads == 1)
- tq = create_singlethread_workqueue(name);
- else
- tq = create_workqueue(name);
+ spin_unlock_irq(&tq->tq_lock);
- return tq;
+ for (i = 0; i < nthreads; i++) {
+ t = kthread_create(taskq_thread, tq, "%s/%d", name, i);
+ if (t) {
+ tq->tq_threads[i] = t;
+ kthread_bind(t, i % num_online_cpus());
+ set_user_nice(t, PRIO_TO_NICE(pri));
+ wake_up_process(t);
+ j++;
+ } else {
+ tq->tq_threads[i] = NULL;
+ rc = 1;
+ }
+ }
+
+ /* Wait for all threads to be started before potential destroy */
+ wait_event(tq->tq_wait_waitq, tq->tq_nthreads == j);
+
+ if (rc) {
+ __taskq_destroy(tq);
+ tq = NULL;
+ }
+
+ RETURN(tq);
}
EXPORT_SYMBOL(__taskq_create);
void
__taskq_destroy(taskq_t *tq)
{
+ task_t *t;
+ int i, nthreads;
ENTRY;
- destroy_workqueue(tq);
- EXIT;
-}
-EXPORT_SYMBOL(__taskq_destroy);
-void
-__taskq_wait(taskq_t *tq)
-{
- ENTRY;
- flush_workqueue(tq);
+ ASSERT(tq);
+ spin_lock_irq(&tq->tq_lock);
+ tq->tq_flags &= ~TQ_ACTIVE;
+ spin_unlock_irq(&tq->tq_lock);
+
+ /* TQ_ACTIVE cleared prevents new tasks being added to pending */
+ __taskq_wait(tq);
+
+ nthreads = tq->tq_nthreads;
+ for (i = 0; i < nthreads; i++)
+ if (tq->tq_threads[i])
+ kthread_stop(tq->tq_threads[i]);
+
+ spin_lock_irq(&tq->tq_lock);
+
+ while (!list_empty(&tq->tq_free_list)) {
+ t = list_entry(tq->tq_free_list.next, task_t, t_list);
+ list_del_init(&t->t_list);
+ task_free(tq, t);
+ }
+
+ ASSERT(tq->tq_nthreads == 0);
+ ASSERT(tq->tq_nalloc == 0);
+ ASSERT(list_empty(&tq->tq_free_list));
+ ASSERT(list_empty(&tq->tq_work_list));
+ ASSERT(list_empty(&tq->tq_pend_list));
+
+ spin_unlock_irq(&tq->tq_lock);
+ kmem_free(tq->tq_threads, nthreads * sizeof(task_t *));
+ kmem_free(tq, sizeof(taskq_t));
+
EXIT;
}
-EXPORT_SYMBOL(__taskq_wait);
+EXPORT_SYMBOL(__taskq_destroy);
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