workqueue: misc/cosmetic updates
Make the following updates in preparation of concurrency managed workqueue. None of these changes causes any visible behavior difference. * Add comments and adjust indentations to data structures and several functions. * Rename wq_per_cpu() to get_cwq() and swap the position of two parameters for consistency. Convert a direct per_cpu_ptr() access to wq->cpu_wq to get_cwq(). * Add work_static() and Update set_wq_data() such that it sets the flags part to WORK_STRUCT_PENDING | WORK_STRUCT_STATIC if static | @extra_flags. * Move santiy check on work->entry emptiness from queue_work_on() to __queue_work() which all queueing paths share. * Make __queue_work() take @cpu and @wq instead of @cwq. * Restructure flush_work() and __create_workqueue_key() to make them easier to modify. Signed-off-by: Tejun Heo <tj@kernel.org>
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Tejun Heo
parent
c790bce048
commit
4690c4ab56
@ -96,9 +96,14 @@ struct execute_work {
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#ifdef CONFIG_DEBUG_OBJECTS_WORK
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extern void __init_work(struct work_struct *work, int onstack);
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extern void destroy_work_on_stack(struct work_struct *work);
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static inline unsigned int work_static(struct work_struct *work)
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{
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return *work_data_bits(work) & (1 << WORK_STRUCT_STATIC);
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}
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#else
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static inline void __init_work(struct work_struct *work, int onstack) { }
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static inline void destroy_work_on_stack(struct work_struct *work) { }
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static inline unsigned int work_static(struct work_struct *work) { return 0; }
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#endif
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/*
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@ -36,6 +36,16 @@
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#define CREATE_TRACE_POINTS
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#include <trace/events/workqueue.h>
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/*
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* Structure fields follow one of the following exclusion rules.
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*
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* I: Set during initialization and read-only afterwards.
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*
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* L: cwq->lock protected. Access with cwq->lock held.
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*
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* W: workqueue_lock protected.
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*/
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/*
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* The per-CPU workqueue (if single thread, we always use the first
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* possible cpu).
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@ -48,7 +58,7 @@ struct cpu_workqueue_struct {
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wait_queue_head_t more_work;
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struct work_struct *current_work;
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struct workqueue_struct *wq;
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struct workqueue_struct *wq; /* I: the owning workqueue */
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struct task_struct *thread;
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} ____cacheline_aligned;
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@ -57,9 +67,9 @@ struct cpu_workqueue_struct {
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* per-CPU workqueues:
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*/
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struct workqueue_struct {
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struct cpu_workqueue_struct *cpu_wq;
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struct list_head list;
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const char *name;
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struct cpu_workqueue_struct *cpu_wq; /* I: cwq's */
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struct list_head list; /* W: list of all workqueues */
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const char *name; /* I: workqueue name */
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int singlethread;
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int freezeable; /* Freeze threads during suspend */
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#ifdef CONFIG_LOCKDEP
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@ -204,8 +214,8 @@ static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq)
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? cpu_singlethread_map : cpu_populated_map;
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}
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static
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struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu)
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static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
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struct workqueue_struct *wq)
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{
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if (unlikely(is_wq_single_threaded(wq)))
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cpu = singlethread_cpu;
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@ -217,15 +227,13 @@ struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu)
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* - Must *only* be called if the pending flag is set
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*/
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static inline void set_wq_data(struct work_struct *work,
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struct cpu_workqueue_struct *cwq)
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struct cpu_workqueue_struct *cwq,
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unsigned long extra_flags)
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{
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unsigned long new;
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BUG_ON(!work_pending(work));
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new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING);
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new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work);
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atomic_long_set(&work->data, new);
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atomic_long_set(&work->data, (unsigned long)cwq | work_static(work) |
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(1UL << WORK_STRUCT_PENDING) | extra_flags);
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}
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/*
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@ -233,9 +241,7 @@ static inline void set_wq_data(struct work_struct *work,
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*/
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static inline void clear_wq_data(struct work_struct *work)
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{
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unsigned long flags = *work_data_bits(work) &
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(1UL << WORK_STRUCT_STATIC);
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atomic_long_set(&work->data, flags);
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atomic_long_set(&work->data, work_static(work));
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}
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static inline
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@ -244,29 +250,47 @@ struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)
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return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK);
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}
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/**
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* insert_work - insert a work into cwq
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* @cwq: cwq @work belongs to
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* @work: work to insert
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* @head: insertion point
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* @extra_flags: extra WORK_STRUCT_* flags to set
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*
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* Insert @work into @cwq after @head.
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*
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* CONTEXT:
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* spin_lock_irq(cwq->lock).
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*/
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static void insert_work(struct cpu_workqueue_struct *cwq,
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struct work_struct *work, struct list_head *head)
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struct work_struct *work, struct list_head *head,
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unsigned int extra_flags)
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{
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trace_workqueue_insertion(cwq->thread, work);
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set_wq_data(work, cwq);
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/* we own @work, set data and link */
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set_wq_data(work, cwq, extra_flags);
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/*
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* Ensure that we get the right work->data if we see the
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* result of list_add() below, see try_to_grab_pending().
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*/
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smp_wmb();
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list_add_tail(&work->entry, head);
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wake_up(&cwq->more_work);
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}
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static void __queue_work(struct cpu_workqueue_struct *cwq,
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static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
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struct work_struct *work)
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{
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struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
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unsigned long flags;
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debug_work_activate(work);
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spin_lock_irqsave(&cwq->lock, flags);
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insert_work(cwq, work, &cwq->worklist);
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BUG_ON(!list_empty(&work->entry));
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insert_work(cwq, work, &cwq->worklist, 0);
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spin_unlock_irqrestore(&cwq->lock, flags);
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}
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@ -308,8 +332,7 @@ queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
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int ret = 0;
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if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
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BUG_ON(!list_empty(&work->entry));
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__queue_work(wq_per_cpu(wq, cpu), work);
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__queue_work(cpu, wq, work);
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ret = 1;
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}
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return ret;
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@ -320,9 +343,8 @@ static void delayed_work_timer_fn(unsigned long __data)
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{
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struct delayed_work *dwork = (struct delayed_work *)__data;
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struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
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struct workqueue_struct *wq = cwq->wq;
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__queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work);
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__queue_work(smp_processor_id(), cwq->wq, &dwork->work);
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}
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/**
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@ -366,7 +388,7 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
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timer_stats_timer_set_start_info(&dwork->timer);
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/* This stores cwq for the moment, for the timer_fn */
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set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id()));
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set_wq_data(work, get_cwq(raw_smp_processor_id(), wq), 0);
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timer->expires = jiffies + delay;
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timer->data = (unsigned long)dwork;
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timer->function = delayed_work_timer_fn;
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@ -430,6 +452,12 @@ static void run_workqueue(struct cpu_workqueue_struct *cwq)
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spin_unlock_irq(&cwq->lock);
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}
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/**
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* worker_thread - the worker thread function
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* @__cwq: cwq to serve
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*
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* The cwq worker thread function.
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*/
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static int worker_thread(void *__cwq)
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{
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struct cpu_workqueue_struct *cwq = __cwq;
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@ -468,6 +496,17 @@ static void wq_barrier_func(struct work_struct *work)
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complete(&barr->done);
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}
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/**
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* insert_wq_barrier - insert a barrier work
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* @cwq: cwq to insert barrier into
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* @barr: wq_barrier to insert
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* @head: insertion point
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*
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* Insert barrier @barr into @cwq before @head.
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*
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* CONTEXT:
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* spin_lock_irq(cwq->lock).
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*/
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static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
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struct wq_barrier *barr, struct list_head *head)
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{
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@ -479,11 +518,10 @@ static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
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*/
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INIT_WORK_ON_STACK(&barr->work, wq_barrier_func);
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__set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
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init_completion(&barr->done);
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debug_work_activate(&barr->work);
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insert_work(cwq, &barr->work, head);
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insert_work(cwq, &barr->work, head, 0);
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}
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static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
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@ -517,9 +555,6 @@ static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
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*
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* We sleep until all works which were queued on entry have been handled,
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* but we are not livelocked by new incoming ones.
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*
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* This function used to run the workqueues itself. Now we just wait for the
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* helper threads to do it.
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*/
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void flush_workqueue(struct workqueue_struct *wq)
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{
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@ -558,7 +593,6 @@ int flush_work(struct work_struct *work)
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lock_map_acquire(&cwq->wq->lockdep_map);
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lock_map_release(&cwq->wq->lockdep_map);
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prev = NULL;
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spin_lock_irq(&cwq->lock);
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if (!list_empty(&work->entry)) {
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/*
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@ -567,22 +601,22 @@ int flush_work(struct work_struct *work)
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*/
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smp_rmb();
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if (unlikely(cwq != get_wq_data(work)))
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goto out;
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goto already_gone;
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prev = &work->entry;
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} else {
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if (cwq->current_work != work)
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goto out;
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goto already_gone;
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prev = &cwq->worklist;
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}
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insert_wq_barrier(cwq, &barr, prev->next);
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out:
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spin_unlock_irq(&cwq->lock);
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if (!prev)
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return 0;
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spin_unlock_irq(&cwq->lock);
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wait_for_completion(&barr.done);
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destroy_work_on_stack(&barr.work);
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return 1;
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already_gone:
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spin_unlock_irq(&cwq->lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(flush_work);
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@ -665,7 +699,7 @@ static void wait_on_work(struct work_struct *work)
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cpu_map = wq_cpu_map(wq);
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for_each_cpu(cpu, cpu_map)
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wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
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wait_on_cpu_work(get_cwq(cpu, wq), work);
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}
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static int __cancel_work_timer(struct work_struct *work,
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@ -782,9 +816,8 @@ EXPORT_SYMBOL(schedule_delayed_work);
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void flush_delayed_work(struct delayed_work *dwork)
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{
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if (del_timer_sync(&dwork->timer)) {
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struct cpu_workqueue_struct *cwq;
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cwq = wq_per_cpu(get_wq_data(&dwork->work)->wq, get_cpu());
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__queue_work(cwq, &dwork->work);
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__queue_work(get_cpu(), get_wq_data(&dwork->work)->wq,
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&dwork->work);
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put_cpu();
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}
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flush_work(&dwork->work);
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@ -991,13 +1024,11 @@ struct workqueue_struct *__create_workqueue_key(const char *name,
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wq = kzalloc(sizeof(*wq), GFP_KERNEL);
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if (!wq)
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return NULL;
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goto err;
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wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
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if (!wq->cpu_wq) {
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kfree(wq);
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return NULL;
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}
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if (!wq->cpu_wq)
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goto err;
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wq->name = name;
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lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
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@ -1041,6 +1072,12 @@ struct workqueue_struct *__create_workqueue_key(const char *name,
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wq = NULL;
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}
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return wq;
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err:
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if (wq) {
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free_percpu(wq->cpu_wq);
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kfree(wq);
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}
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return NULL;
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}
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EXPORT_SYMBOL_GPL(__create_workqueue_key);
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