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workqueue: Relocate worker and work management functions
Collect first_idle_worker(), worker_enter/leave_idle(), find_worker_executing_work(), move_linked_works() and wake_up_worker() into one place. These functions will later be used to implement higher level worker management logic. No functional changes. Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo
parent
ee1ceef727
commit
797e8345cb
@ -869,36 +869,6 @@ static bool too_many_workers(struct worker_pool *pool)
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return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
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}
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/*
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* Wake up functions.
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*/
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/* Return the first idle worker. Called with pool->lock held. */
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static struct worker *first_idle_worker(struct worker_pool *pool)
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{
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if (unlikely(list_empty(&pool->idle_list)))
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return NULL;
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return list_first_entry(&pool->idle_list, struct worker, entry);
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}
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/**
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* wake_up_worker - wake up an idle worker
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* @pool: worker pool to wake worker from
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*
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* Wake up the first idle worker of @pool.
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*
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* CONTEXT:
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* raw_spin_lock_irq(pool->lock).
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*/
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static void wake_up_worker(struct worker_pool *pool)
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{
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struct worker *worker = first_idle_worker(pool);
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if (likely(worker))
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wake_up_process(worker->task);
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}
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/**
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* worker_set_flags - set worker flags and adjust nr_running accordingly
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* @worker: self
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@ -947,6 +917,174 @@ static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
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pool->nr_running++;
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}
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/* Return the first idle worker. Called with pool->lock held. */
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static struct worker *first_idle_worker(struct worker_pool *pool)
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{
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if (unlikely(list_empty(&pool->idle_list)))
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return NULL;
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return list_first_entry(&pool->idle_list, struct worker, entry);
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}
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/**
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* worker_enter_idle - enter idle state
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* @worker: worker which is entering idle state
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*
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* @worker is entering idle state. Update stats and idle timer if
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* necessary.
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*
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* LOCKING:
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* raw_spin_lock_irq(pool->lock).
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*/
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static void worker_enter_idle(struct worker *worker)
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{
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struct worker_pool *pool = worker->pool;
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if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
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WARN_ON_ONCE(!list_empty(&worker->entry) &&
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(worker->hentry.next || worker->hentry.pprev)))
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return;
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/* can't use worker_set_flags(), also called from create_worker() */
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worker->flags |= WORKER_IDLE;
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pool->nr_idle++;
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worker->last_active = jiffies;
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/* idle_list is LIFO */
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list_add(&worker->entry, &pool->idle_list);
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if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
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mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
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/* Sanity check nr_running. */
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WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running);
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}
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/**
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* worker_leave_idle - leave idle state
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* @worker: worker which is leaving idle state
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*
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* @worker is leaving idle state. Update stats.
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*
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* LOCKING:
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* raw_spin_lock_irq(pool->lock).
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*/
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static void worker_leave_idle(struct worker *worker)
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{
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struct worker_pool *pool = worker->pool;
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if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
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return;
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worker_clr_flags(worker, WORKER_IDLE);
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pool->nr_idle--;
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list_del_init(&worker->entry);
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}
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/**
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* find_worker_executing_work - find worker which is executing a work
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* @pool: pool of interest
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* @work: work to find worker for
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*
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* Find a worker which is executing @work on @pool by searching
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* @pool->busy_hash which is keyed by the address of @work. For a worker
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* to match, its current execution should match the address of @work and
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* its work function. This is to avoid unwanted dependency between
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* unrelated work executions through a work item being recycled while still
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* being executed.
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*
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* This is a bit tricky. A work item may be freed once its execution
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* starts and nothing prevents the freed area from being recycled for
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* another work item. If the same work item address ends up being reused
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* before the original execution finishes, workqueue will identify the
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* recycled work item as currently executing and make it wait until the
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* current execution finishes, introducing an unwanted dependency.
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*
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* This function checks the work item address and work function to avoid
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* false positives. Note that this isn't complete as one may construct a
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* work function which can introduce dependency onto itself through a
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* recycled work item. Well, if somebody wants to shoot oneself in the
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* foot that badly, there's only so much we can do, and if such deadlock
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* actually occurs, it should be easy to locate the culprit work function.
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*
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* CONTEXT:
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* raw_spin_lock_irq(pool->lock).
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*
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* Return:
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* Pointer to worker which is executing @work if found, %NULL
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* otherwise.
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*/
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static struct worker *find_worker_executing_work(struct worker_pool *pool,
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struct work_struct *work)
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{
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struct worker *worker;
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hash_for_each_possible(pool->busy_hash, worker, hentry,
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(unsigned long)work)
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if (worker->current_work == work &&
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worker->current_func == work->func)
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return worker;
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return NULL;
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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 parameter 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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* raw_spin_lock_irq(pool->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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/**
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* wake_up_worker - wake up an idle worker
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* @pool: worker pool to wake worker from
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*
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* Wake up the first idle worker of @pool.
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*
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* CONTEXT:
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* raw_spin_lock_irq(pool->lock).
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*/
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static void wake_up_worker(struct worker_pool *pool)
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{
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struct worker *worker = first_idle_worker(pool);
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if (likely(worker))
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wake_up_process(worker->task);
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}
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#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT
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/*
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@ -1202,94 +1340,6 @@ work_func_t wq_worker_last_func(struct task_struct *task)
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return worker->last_func;
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}
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/**
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* find_worker_executing_work - find worker which is executing a work
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* @pool: pool of interest
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* @work: work to find worker for
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*
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* Find a worker which is executing @work on @pool by searching
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* @pool->busy_hash which is keyed by the address of @work. For a worker
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* to match, its current execution should match the address of @work and
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* its work function. This is to avoid unwanted dependency between
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* unrelated work executions through a work item being recycled while still
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* being executed.
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*
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* This is a bit tricky. A work item may be freed once its execution
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* starts and nothing prevents the freed area from being recycled for
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* another work item. If the same work item address ends up being reused
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* before the original execution finishes, workqueue will identify the
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* recycled work item as currently executing and make it wait until the
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* current execution finishes, introducing an unwanted dependency.
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*
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* This function checks the work item address and work function to avoid
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* false positives. Note that this isn't complete as one may construct a
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* work function which can introduce dependency onto itself through a
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* recycled work item. Well, if somebody wants to shoot oneself in the
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* foot that badly, there's only so much we can do, and if such deadlock
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* actually occurs, it should be easy to locate the culprit work function.
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*
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* CONTEXT:
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* raw_spin_lock_irq(pool->lock).
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*
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* Return:
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* Pointer to worker which is executing @work if found, %NULL
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* otherwise.
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*/
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static struct worker *find_worker_executing_work(struct worker_pool *pool,
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struct work_struct *work)
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{
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struct worker *worker;
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hash_for_each_possible(pool->busy_hash, worker, hentry,
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(unsigned long)work)
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if (worker->current_work == work &&
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worker->current_func == work->func)
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return worker;
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return NULL;
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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 parameter 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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* raw_spin_lock_irq(pool->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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/**
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* get_pwq - get an extra reference on the specified pool_workqueue
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* @pwq: pool_workqueue to get
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@ -1974,60 +2024,6 @@ bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork)
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}
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EXPORT_SYMBOL(queue_rcu_work);
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/**
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* worker_enter_idle - enter idle state
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* @worker: worker which is entering idle state
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*
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* @worker is entering idle state. Update stats and idle timer if
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* necessary.
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*
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* LOCKING:
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* raw_spin_lock_irq(pool->lock).
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*/
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static void worker_enter_idle(struct worker *worker)
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{
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struct worker_pool *pool = worker->pool;
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if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
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WARN_ON_ONCE(!list_empty(&worker->entry) &&
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(worker->hentry.next || worker->hentry.pprev)))
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return;
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/* can't use worker_set_flags(), also called from create_worker() */
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worker->flags |= WORKER_IDLE;
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pool->nr_idle++;
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worker->last_active = jiffies;
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/* idle_list is LIFO */
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list_add(&worker->entry, &pool->idle_list);
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if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
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mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
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/* Sanity check nr_running. */
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WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running);
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}
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/**
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* worker_leave_idle - leave idle state
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* @worker: worker which is leaving idle state
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*
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* @worker is leaving idle state. Update stats.
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*
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* LOCKING:
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* raw_spin_lock_irq(pool->lock).
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*/
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static void worker_leave_idle(struct worker *worker)
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{
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struct worker_pool *pool = worker->pool;
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if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
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return;
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worker_clr_flags(worker, WORKER_IDLE);
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pool->nr_idle--;
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list_del_init(&worker->entry);
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}
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static struct worker *alloc_worker(int node)
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{
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struct worker *worker;
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