workqueue: move try_to_grab_pending() upwards
try_to_grab_pending() will be used by to-be-implemented mod_delayed_work[_on](). Move try_to_grab_pending() and related functions above queueing functions. This patch only moves functions around. Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo
parent
715f130080
commit
bf4ede014e
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@ -903,6 +903,149 @@ static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
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work);
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}
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/**
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* move_linked_works - move linked works to a list
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* @work: start of series of works to be scheduled
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* @head: target list to append @work to
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* @nextp: out paramter for nested worklist walking
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*
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* Schedule linked works starting from @work to @head. Work series to
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* be scheduled starts at @work and includes any consecutive work with
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* WORK_STRUCT_LINKED set in its predecessor.
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*
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* If @nextp is not NULL, it's updated to point to the next work of
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* the last scheduled work. This allows move_linked_works() to be
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* nested inside outer list_for_each_entry_safe().
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*
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* CONTEXT:
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* spin_lock_irq(gcwq->lock).
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*/
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static void move_linked_works(struct work_struct *work, struct list_head *head,
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struct work_struct **nextp)
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{
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struct work_struct *n;
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/*
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* Linked worklist will always end before the end of the list,
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* use NULL for list head.
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*/
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list_for_each_entry_safe_from(work, n, NULL, entry) {
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list_move_tail(&work->entry, head);
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if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
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break;
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}
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/*
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* If we're already inside safe list traversal and have moved
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* multiple works to the scheduled queue, the next position
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* needs to be updated.
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*/
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if (nextp)
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*nextp = n;
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}
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static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
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{
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struct work_struct *work = list_first_entry(&cwq->delayed_works,
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struct work_struct, entry);
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trace_workqueue_activate_work(work);
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move_linked_works(work, &cwq->pool->worklist, NULL);
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__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
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cwq->nr_active++;
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}
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/**
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* cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
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* @cwq: cwq of interest
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* @color: color of work which left the queue
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* @delayed: for a delayed work
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*
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* A work either has completed or is removed from pending queue,
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* decrement nr_in_flight of its cwq and handle workqueue flushing.
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*
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* CONTEXT:
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* spin_lock_irq(gcwq->lock).
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*/
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static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
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bool delayed)
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{
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/* ignore uncolored works */
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if (color == WORK_NO_COLOR)
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return;
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cwq->nr_in_flight[color]--;
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if (!delayed) {
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cwq->nr_active--;
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if (!list_empty(&cwq->delayed_works)) {
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/* one down, submit a delayed one */
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if (cwq->nr_active < cwq->max_active)
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cwq_activate_first_delayed(cwq);
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}
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}
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/* is flush in progress and are we at the flushing tip? */
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if (likely(cwq->flush_color != color))
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return;
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/* are there still in-flight works? */
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if (cwq->nr_in_flight[color])
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return;
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/* this cwq is done, clear flush_color */
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cwq->flush_color = -1;
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/*
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* If this was the last cwq, wake up the first flusher. It
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* will handle the rest.
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*/
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if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
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complete(&cwq->wq->first_flusher->done);
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}
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/*
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* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
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* so this work can't be re-armed in any way.
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*/
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static int try_to_grab_pending(struct work_struct *work)
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{
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struct global_cwq *gcwq;
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int ret = -1;
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if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
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return 0;
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/*
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* The queueing is in progress, or it is already queued. Try to
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* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
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*/
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gcwq = get_work_gcwq(work);
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if (!gcwq)
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return ret;
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spin_lock_irq(&gcwq->lock);
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if (!list_empty(&work->entry)) {
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/*
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* This work is queued, but perhaps we locked the wrong gcwq.
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* In that case we must see the new value after rmb(), see
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* insert_work()->wmb().
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*/
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smp_rmb();
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if (gcwq == get_work_gcwq(work)) {
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debug_work_deactivate(work);
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list_del_init(&work->entry);
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cwq_dec_nr_in_flight(get_work_cwq(work),
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get_work_color(work),
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*work_data_bits(work) & WORK_STRUCT_DELAYED);
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ret = 1;
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}
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}
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spin_unlock_irq(&gcwq->lock);
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return ret;
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}
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/**
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* insert_work - insert a work into gcwq
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* @cwq: cwq @work belongs to
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@ -1831,107 +1974,6 @@ static bool manage_workers(struct worker *worker)
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return ret;
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}
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/**
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* move_linked_works - move linked works to a list
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* @work: start of series of works to be scheduled
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* @head: target list to append @work to
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* @nextp: out paramter for nested worklist walking
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*
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* Schedule linked works starting from @work to @head. Work series to
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* be scheduled starts at @work and includes any consecutive work with
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* WORK_STRUCT_LINKED set in its predecessor.
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*
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* If @nextp is not NULL, it's updated to point to the next work of
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* the last scheduled work. This allows move_linked_works() to be
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* nested inside outer list_for_each_entry_safe().
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*
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* CONTEXT:
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* spin_lock_irq(gcwq->lock).
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*/
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static void move_linked_works(struct work_struct *work, struct list_head *head,
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struct work_struct **nextp)
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{
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struct work_struct *n;
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/*
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* Linked worklist will always end before the end of the list,
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* use NULL for list head.
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*/
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list_for_each_entry_safe_from(work, n, NULL, entry) {
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list_move_tail(&work->entry, head);
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if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
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break;
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}
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/*
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* If we're already inside safe list traversal and have moved
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* multiple works to the scheduled queue, the next position
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* needs to be updated.
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*/
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if (nextp)
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*nextp = n;
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}
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static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
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{
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struct work_struct *work = list_first_entry(&cwq->delayed_works,
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struct work_struct, entry);
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trace_workqueue_activate_work(work);
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move_linked_works(work, &cwq->pool->worklist, NULL);
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__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
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cwq->nr_active++;
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}
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/**
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* cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
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* @cwq: cwq of interest
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* @color: color of work which left the queue
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* @delayed: for a delayed work
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*
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* A work either has completed or is removed from pending queue,
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* decrement nr_in_flight of its cwq and handle workqueue flushing.
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*
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* CONTEXT:
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* spin_lock_irq(gcwq->lock).
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*/
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static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
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bool delayed)
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{
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/* ignore uncolored works */
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if (color == WORK_NO_COLOR)
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return;
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cwq->nr_in_flight[color]--;
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if (!delayed) {
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cwq->nr_active--;
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if (!list_empty(&cwq->delayed_works)) {
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/* one down, submit a delayed one */
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if (cwq->nr_active < cwq->max_active)
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cwq_activate_first_delayed(cwq);
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}
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}
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/* is flush in progress and are we at the flushing tip? */
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if (likely(cwq->flush_color != color))
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return;
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/* are there still in-flight works? */
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if (cwq->nr_in_flight[color])
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return;
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/* this cwq is done, clear flush_color */
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cwq->flush_color = -1;
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/*
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* If this was the last cwq, wake up the first flusher. It
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* will handle the rest.
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*/
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if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
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complete(&cwq->wq->first_flusher->done);
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}
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/**
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* process_one_work - process single work
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* @worker: self
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@ -2767,48 +2809,6 @@ bool flush_work_sync(struct work_struct *work)
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}
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EXPORT_SYMBOL_GPL(flush_work_sync);
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/*
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* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
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* so this work can't be re-armed in any way.
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*/
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static int try_to_grab_pending(struct work_struct *work)
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{
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struct global_cwq *gcwq;
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int ret = -1;
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if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
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return 0;
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/*
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* The queueing is in progress, or it is already queued. Try to
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* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
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*/
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gcwq = get_work_gcwq(work);
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if (!gcwq)
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return ret;
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spin_lock_irq(&gcwq->lock);
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if (!list_empty(&work->entry)) {
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/*
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* This work is queued, but perhaps we locked the wrong gcwq.
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* In that case we must see the new value after rmb(), see
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* insert_work()->wmb().
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*/
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smp_rmb();
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if (gcwq == get_work_gcwq(work)) {
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debug_work_deactivate(work);
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list_del_init(&work->entry);
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cwq_dec_nr_in_flight(get_work_cwq(work),
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get_work_color(work),
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*work_data_bits(work) & WORK_STRUCT_DELAYED);
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ret = 1;
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}
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}
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spin_unlock_irq(&gcwq->lock);
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return ret;
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}
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static bool __cancel_work_timer(struct work_struct *work,
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struct timer_list* timer)
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{
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