Skip to content

Commit

Permalink
workqueue: move try_to_grab_pending() upwards
Browse files Browse the repository at this point in the history 
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>
  • Loading branch information
Tejun Heo committed Aug 3, 2012
1 parent 715f130 commit bf4ede0
Showing 1 changed file with 143 additions and 143 deletions.
286 changes: 143 additions & 143 deletions kernel/workqueue.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -903,6 +903,149 @@ static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
work);
}

/**
* move_linked_works - move linked works to a list
* @work: start of series of works to be scheduled
* @head: target list to append @work to
* @nextp: out paramter for nested worklist walking
*
* Schedule linked works starting from @work to @head. Work series to
* be scheduled starts at @work and includes any consecutive work with
* WORK_STRUCT_LINKED set in its predecessor.
*
* If @nextp is not NULL, it's updated to point to the next work of
* the last scheduled work. This allows move_linked_works() to be
* nested inside outer list_for_each_entry_safe().
*
* CONTEXT:
* spin_lock_irq(gcwq->lock).
*/
static void move_linked_works(struct work_struct *work, struct list_head *head,
struct work_struct **nextp)
{
struct work_struct *n;

/*
* Linked worklist will always end before the end of the list,
* use NULL for list head.
*/
list_for_each_entry_safe_from(work, n, NULL, entry) {
list_move_tail(&work->entry, head);
if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
break;
}

/*
* If we're already inside safe list traversal and have moved
* multiple works to the scheduled queue, the next position
* needs to be updated.
*/
if (nextp)
*nextp = n;
}

static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
{
struct work_struct *work = list_first_entry(&cwq->delayed_works,
struct work_struct, entry);

trace_workqueue_activate_work(work);
move_linked_works(work, &cwq->pool->worklist, NULL);
__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
cwq->nr_active++;
}

/**
* cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
* @cwq: cwq of interest
* @color: color of work which left the queue
* @delayed: for a delayed work
*
* A work either has completed or is removed from pending queue,
* decrement nr_in_flight of its cwq and handle workqueue flushing.
*
* CONTEXT:
* spin_lock_irq(gcwq->lock).
*/
static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
bool delayed)
{
/* ignore uncolored works */
if (color == WORK_NO_COLOR)
return;

cwq->nr_in_flight[color]--;

if (!delayed) {
cwq->nr_active--;
if (!list_empty(&cwq->delayed_works)) {
/* one down, submit a delayed one */
if (cwq->nr_active < cwq->max_active)
cwq_activate_first_delayed(cwq);
}
}

/* is flush in progress and are we at the flushing tip? */
if (likely(cwq->flush_color != color))
return;

/* are there still in-flight works? */
if (cwq->nr_in_flight[color])
return;

/* this cwq is done, clear flush_color */
cwq->flush_color = -1;

/*
* If this was the last cwq, wake up the first flusher. It
* will handle the rest.
*/
if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
complete(&cwq->wq->first_flusher->done);
}

/*
* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
* so this work can't be re-armed in any way.
*/
static int try_to_grab_pending(struct work_struct *work)
{
struct global_cwq *gcwq;
int ret = -1;

if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
return 0;

/*
* The queueing is in progress, or it is already queued. Try to
* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
*/
gcwq = get_work_gcwq(work);
if (!gcwq)
return ret;

spin_lock_irq(&gcwq->lock);
if (!list_empty(&work->entry)) {
/*
* This work is queued, but perhaps we locked the wrong gcwq.
* In that case we must see the new value after rmb(), see
* insert_work()->wmb().
*/
smp_rmb();
if (gcwq == get_work_gcwq(work)) {
debug_work_deactivate(work);
list_del_init(&work->entry);
cwq_dec_nr_in_flight(get_work_cwq(work),
get_work_color(work),
*work_data_bits(work) & WORK_STRUCT_DELAYED);
ret = 1;
}
}
spin_unlock_irq(&gcwq->lock);

return ret;
}

/**
* insert_work - insert a work into gcwq
* @cwq: cwq @work belongs to
Expand Down Expand Up @@ -1831,107 +1974,6 @@ static bool manage_workers(struct worker *worker)
return ret;
}

/**
* move_linked_works - move linked works to a list
* @work: start of series of works to be scheduled
* @head: target list to append @work to
* @nextp: out paramter for nested worklist walking
*
* Schedule linked works starting from @work to @head. Work series to
* be scheduled starts at @work and includes any consecutive work with
* WORK_STRUCT_LINKED set in its predecessor.
*
* If @nextp is not NULL, it's updated to point to the next work of
* the last scheduled work. This allows move_linked_works() to be
* nested inside outer list_for_each_entry_safe().
*
* CONTEXT:
* spin_lock_irq(gcwq->lock).
*/
static void move_linked_works(struct work_struct *work, struct list_head *head,
struct work_struct **nextp)
{
struct work_struct *n;

/*
* Linked worklist will always end before the end of the list,
* use NULL for list head.
*/
list_for_each_entry_safe_from(work, n, NULL, entry) {
list_move_tail(&work->entry, head);
if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
break;
}

/*
* If we're already inside safe list traversal and have moved
* multiple works to the scheduled queue, the next position
* needs to be updated.
*/
if (nextp)
*nextp = n;
}

static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
{
struct work_struct *work = list_first_entry(&cwq->delayed_works,
struct work_struct, entry);

trace_workqueue_activate_work(work);
move_linked_works(work, &cwq->pool->worklist, NULL);
__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
cwq->nr_active++;
}

/**
* cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
* @cwq: cwq of interest
* @color: color of work which left the queue
* @delayed: for a delayed work
*
* A work either has completed or is removed from pending queue,
* decrement nr_in_flight of its cwq and handle workqueue flushing.
*
* CONTEXT:
* spin_lock_irq(gcwq->lock).
*/
static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
bool delayed)
{
/* ignore uncolored works */
if (color == WORK_NO_COLOR)
return;

cwq->nr_in_flight[color]--;

if (!delayed) {
cwq->nr_active--;
if (!list_empty(&cwq->delayed_works)) {
/* one down, submit a delayed one */
if (cwq->nr_active < cwq->max_active)
cwq_activate_first_delayed(cwq);
}
}

/* is flush in progress and are we at the flushing tip? */
if (likely(cwq->flush_color != color))
return;

/* are there still in-flight works? */
if (cwq->nr_in_flight[color])
return;

/* this cwq is done, clear flush_color */
cwq->flush_color = -1;

/*
* If this was the last cwq, wake up the first flusher. It
* will handle the rest.
*/
if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
complete(&cwq->wq->first_flusher->done);
}

/**
* process_one_work - process single work
* @worker: self
Expand Down Expand Up @@ -2767,48 +2809,6 @@ bool flush_work_sync(struct work_struct *work)
}
EXPORT_SYMBOL_GPL(flush_work_sync);

/*
* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
* so this work can't be re-armed in any way.
*/
static int try_to_grab_pending(struct work_struct *work)
{
struct global_cwq *gcwq;
int ret = -1;

if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
return 0;

/*
* The queueing is in progress, or it is already queued. Try to
* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
*/
gcwq = get_work_gcwq(work);
if (!gcwq)
return ret;

spin_lock_irq(&gcwq->lock);
if (!list_empty(&work->entry)) {
/*
* This work is queued, but perhaps we locked the wrong gcwq.
* In that case we must see the new value after rmb(), see
* insert_work()->wmb().
*/
smp_rmb();
if (gcwq == get_work_gcwq(work)) {
debug_work_deactivate(work);
list_del_init(&work->entry);
cwq_dec_nr_in_flight(get_work_cwq(work),
get_work_color(work),
*work_data_bits(work) & WORK_STRUCT_DELAYED);
ret = 1;
}
}
spin_unlock_irq(&gcwq->lock);

return ret;
}

static bool __cancel_work_timer(struct work_struct *work,
struct timer_list* timer)
{
Expand Down

0 comments on commit bf4ede0

Please sign in to comment.