| /* |
| * linux/kernel/workqueue.c |
| * |
| * Generic mechanism for defining kernel helper threads for running |
| * arbitrary tasks in process context. |
| * |
| * Started by Ingo Molnar, Copyright (C) 2002 |
| * |
| * Derived from the taskqueue/keventd code by: |
| * |
| * David Woodhouse <dwmw2@infradead.org> |
| * Andrew Morton |
| * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
| * Theodore Ts'o <tytso@mit.edu> |
| * |
| * Made to use alloc_percpu by Christoph Lameter. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/sched.h> |
| #include <linux/init.h> |
| #include <linux/signal.h> |
| #include <linux/completion.h> |
| #include <linux/workqueue.h> |
| #include <linux/slab.h> |
| #include <linux/cpu.h> |
| #include <linux/notifier.h> |
| #include <linux/kthread.h> |
| #include <linux/hardirq.h> |
| #include <linux/mempolicy.h> |
| #include <linux/freezer.h> |
| #include <linux/kallsyms.h> |
| #include <linux/debug_locks.h> |
| #include <linux/lockdep.h> |
| #include <linux/idr.h> |
| |
| enum { |
| /* global_cwq flags */ |
| GCWQ_FREEZING = 1 << 3, /* freeze in progress */ |
| |
| /* worker flags */ |
| WORKER_STARTED = 1 << 0, /* started */ |
| WORKER_DIE = 1 << 1, /* die die die */ |
| WORKER_IDLE = 1 << 2, /* is idle */ |
| WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ |
| |
| /* gcwq->trustee_state */ |
| TRUSTEE_START = 0, /* start */ |
| TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ |
| TRUSTEE_BUTCHER = 2, /* butcher workers */ |
| TRUSTEE_RELEASE = 3, /* release workers */ |
| TRUSTEE_DONE = 4, /* trustee is done */ |
| |
| BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
| BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, |
| BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, |
| |
| TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ |
| }; |
| |
| /* |
| * Structure fields follow one of the following exclusion rules. |
| * |
| * I: Set during initialization and read-only afterwards. |
| * |
| * L: gcwq->lock protected. Access with gcwq->lock held. |
| * |
| * F: wq->flush_mutex protected. |
| * |
| * W: workqueue_lock protected. |
| */ |
| |
| struct global_cwq; |
| struct cpu_workqueue_struct; |
| |
| struct worker { |
| /* on idle list while idle, on busy hash table while busy */ |
| union { |
| struct list_head entry; /* L: while idle */ |
| struct hlist_node hentry; /* L: while busy */ |
| }; |
| |
| struct work_struct *current_work; /* L: work being processed */ |
| struct list_head scheduled; /* L: scheduled works */ |
| struct task_struct *task; /* I: worker task */ |
| struct global_cwq *gcwq; /* I: the associated gcwq */ |
| struct cpu_workqueue_struct *cwq; /* I: the associated cwq */ |
| unsigned int flags; /* L: flags */ |
| int id; /* I: worker id */ |
| }; |
| |
| /* |
| * Global per-cpu workqueue. |
| */ |
| struct global_cwq { |
| spinlock_t lock; /* the gcwq lock */ |
| unsigned int cpu; /* I: the associated cpu */ |
| unsigned int flags; /* L: GCWQ_* flags */ |
| |
| int nr_workers; /* L: total number of workers */ |
| int nr_idle; /* L: currently idle ones */ |
| |
| /* workers are chained either in the idle_list or busy_hash */ |
| struct list_head idle_list; /* L: list of idle workers */ |
| struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; |
| /* L: hash of busy workers */ |
| |
| struct ida worker_ida; /* L: for worker IDs */ |
| |
| struct task_struct *trustee; /* L: for gcwq shutdown */ |
| unsigned int trustee_state; /* L: trustee state */ |
| wait_queue_head_t trustee_wait; /* trustee wait */ |
| } ____cacheline_aligned_in_smp; |
| |
| /* |
| * The per-CPU workqueue (if single thread, we always use the first |
| * possible cpu). The lower WORK_STRUCT_FLAG_BITS of |
| * work_struct->data are used for flags and thus cwqs need to be |
| * aligned at two's power of the number of flag bits. |
| */ |
| struct cpu_workqueue_struct { |
| struct global_cwq *gcwq; /* I: the associated gcwq */ |
| struct list_head worklist; |
| struct worker *worker; |
| struct workqueue_struct *wq; /* I: the owning workqueue */ |
| int work_color; /* L: current color */ |
| int flush_color; /* L: flushing color */ |
| int nr_in_flight[WORK_NR_COLORS]; |
| /* L: nr of in_flight works */ |
| int nr_active; /* L: nr of active works */ |
| int max_active; /* L: max active works */ |
| struct list_head delayed_works; /* L: delayed works */ |
| }; |
| |
| /* |
| * Structure used to wait for workqueue flush. |
| */ |
| struct wq_flusher { |
| struct list_head list; /* F: list of flushers */ |
| int flush_color; /* F: flush color waiting for */ |
| struct completion done; /* flush completion */ |
| }; |
| |
| /* |
| * The externally visible workqueue abstraction is an array of |
| * per-CPU workqueues: |
| */ |
| struct workqueue_struct { |
| unsigned int flags; /* I: WQ_* flags */ |
| struct cpu_workqueue_struct *cpu_wq; /* I: cwq's */ |
| struct list_head list; /* W: list of all workqueues */ |
| |
| struct mutex flush_mutex; /* protects wq flushing */ |
| int work_color; /* F: current work color */ |
| int flush_color; /* F: current flush color */ |
| atomic_t nr_cwqs_to_flush; /* flush in progress */ |
| struct wq_flusher *first_flusher; /* F: first flusher */ |
| struct list_head flusher_queue; /* F: flush waiters */ |
| struct list_head flusher_overflow; /* F: flush overflow list */ |
| |
| int saved_max_active; /* I: saved cwq max_active */ |
| const char *name; /* I: workqueue name */ |
| #ifdef CONFIG_LOCKDEP |
| struct lockdep_map lockdep_map; |
| #endif |
| }; |
| |
| #define for_each_busy_worker(worker, i, pos, gcwq) \ |
| for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ |
| hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) |
| |
| #ifdef CONFIG_DEBUG_OBJECTS_WORK |
| |
| static struct debug_obj_descr work_debug_descr; |
| |
| /* |
| * fixup_init is called when: |
| * - an active object is initialized |
| */ |
| static int work_fixup_init(void *addr, enum debug_obj_state state) |
| { |
| struct work_struct *work = addr; |
| |
| switch (state) { |
| case ODEBUG_STATE_ACTIVE: |
| cancel_work_sync(work); |
| debug_object_init(work, &work_debug_descr); |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| /* |
| * fixup_activate is called when: |
| * - an active object is activated |
| * - an unknown object is activated (might be a statically initialized object) |
| */ |
| static int work_fixup_activate(void *addr, enum debug_obj_state state) |
| { |
| struct work_struct *work = addr; |
| |
| switch (state) { |
| |
| case ODEBUG_STATE_NOTAVAILABLE: |
| /* |
| * This is not really a fixup. The work struct was |
| * statically initialized. We just make sure that it |
| * is tracked in the object tracker. |
| */ |
| if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
| debug_object_init(work, &work_debug_descr); |
| debug_object_activate(work, &work_debug_descr); |
| return 0; |
| } |
| WARN_ON_ONCE(1); |
| return 0; |
| |
| case ODEBUG_STATE_ACTIVE: |
| WARN_ON(1); |
| |
| default: |
| return 0; |
| } |
| } |
| |
| /* |
| * fixup_free is called when: |
| * - an active object is freed |
| */ |
| static int work_fixup_free(void *addr, enum debug_obj_state state) |
| { |
| struct work_struct *work = addr; |
| |
| switch (state) { |
| case ODEBUG_STATE_ACTIVE: |
| cancel_work_sync(work); |
| debug_object_free(work, &work_debug_descr); |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| static struct debug_obj_descr work_debug_descr = { |
| .name = "work_struct", |
| .fixup_init = work_fixup_init, |
| .fixup_activate = work_fixup_activate, |
| .fixup_free = work_fixup_free, |
| }; |
| |
| static inline void debug_work_activate(struct work_struct *work) |
| { |
| debug_object_activate(work, &work_debug_descr); |
| } |
| |
| static inline void debug_work_deactivate(struct work_struct *work) |
| { |
| debug_object_deactivate(work, &work_debug_descr); |
| } |
| |
| void __init_work(struct work_struct *work, int onstack) |
| { |
| if (onstack) |
| debug_object_init_on_stack(work, &work_debug_descr); |
| else |
| debug_object_init(work, &work_debug_descr); |
| } |
| EXPORT_SYMBOL_GPL(__init_work); |
| |
| void destroy_work_on_stack(struct work_struct *work) |
| { |
| debug_object_free(work, &work_debug_descr); |
| } |
| EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
| |
| #else |
| static inline void debug_work_activate(struct work_struct *work) { } |
| static inline void debug_work_deactivate(struct work_struct *work) { } |
| #endif |
| |
| /* Serializes the accesses to the list of workqueues. */ |
| static DEFINE_SPINLOCK(workqueue_lock); |
| static LIST_HEAD(workqueues); |
| static bool workqueue_freezing; /* W: have wqs started freezing? */ |
| |
| static DEFINE_PER_CPU(struct global_cwq, global_cwq); |
| |
| static int worker_thread(void *__worker); |
| |
| static int singlethread_cpu __read_mostly; |
| |
| static struct global_cwq *get_gcwq(unsigned int cpu) |
| { |
| return &per_cpu(global_cwq, cpu); |
| } |
| |
| static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, |
| struct workqueue_struct *wq) |
| { |
| return per_cpu_ptr(wq->cpu_wq, cpu); |
| } |
| |
| static struct cpu_workqueue_struct *target_cwq(unsigned int cpu, |
| struct workqueue_struct *wq) |
| { |
| if (unlikely(wq->flags & WQ_SINGLE_THREAD)) |
| cpu = singlethread_cpu; |
| return get_cwq(cpu, wq); |
| } |
| |
| static unsigned int work_color_to_flags(int color) |
| { |
| return color << WORK_STRUCT_COLOR_SHIFT; |
| } |
| |
| static int get_work_color(struct work_struct *work) |
| { |
| return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & |
| ((1 << WORK_STRUCT_COLOR_BITS) - 1); |
| } |
| |
| static int work_next_color(int color) |
| { |
| return (color + 1) % WORK_NR_COLORS; |
| } |
| |
| /* |
| * Set the workqueue on which a work item is to be run |
| * - Must *only* be called if the pending flag is set |
| */ |
| static inline void set_wq_data(struct work_struct *work, |
| struct cpu_workqueue_struct *cwq, |
| unsigned long extra_flags) |
| { |
| BUG_ON(!work_pending(work)); |
| |
| atomic_long_set(&work->data, (unsigned long)cwq | work_static(work) | |
| WORK_STRUCT_PENDING | extra_flags); |
| } |
| |
| /* |
| * Clear WORK_STRUCT_PENDING and the workqueue on which it was queued. |
| */ |
| static inline void clear_wq_data(struct work_struct *work) |
| { |
| atomic_long_set(&work->data, work_static(work)); |
| } |
| |
| static inline struct cpu_workqueue_struct *get_wq_data(struct work_struct *work) |
| { |
| return (void *)(atomic_long_read(&work->data) & |
| WORK_STRUCT_WQ_DATA_MASK); |
| } |
| |
| /** |
| * busy_worker_head - return the busy hash head for a work |
| * @gcwq: gcwq of interest |
| * @work: work to be hashed |
| * |
| * Return hash head of @gcwq for @work. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| * |
| * RETURNS: |
| * Pointer to the hash head. |
| */ |
| static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, |
| struct work_struct *work) |
| { |
| const int base_shift = ilog2(sizeof(struct work_struct)); |
| unsigned long v = (unsigned long)work; |
| |
| /* simple shift and fold hash, do we need something better? */ |
| v >>= base_shift; |
| v += v >> BUSY_WORKER_HASH_ORDER; |
| v &= BUSY_WORKER_HASH_MASK; |
| |
| return &gcwq->busy_hash[v]; |
| } |
| |
| /** |
| * insert_work - insert a work into cwq |
| * @cwq: cwq @work belongs to |
| * @work: work to insert |
| * @head: insertion point |
| * @extra_flags: extra WORK_STRUCT_* flags to set |
| * |
| * Insert @work into @cwq after @head. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void insert_work(struct cpu_workqueue_struct *cwq, |
| struct work_struct *work, struct list_head *head, |
| unsigned int extra_flags) |
| { |
| /* we own @work, set data and link */ |
| set_wq_data(work, cwq, extra_flags); |
| |
| /* |
| * Ensure that we get the right work->data if we see the |
| * result of list_add() below, see try_to_grab_pending(). |
| */ |
| smp_wmb(); |
| |
| list_add_tail(&work->entry, head); |
| wake_up_process(cwq->worker->task); |
| } |
| |
| static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
| struct work_struct *work) |
| { |
| struct cpu_workqueue_struct *cwq = target_cwq(cpu, wq); |
| struct global_cwq *gcwq = cwq->gcwq; |
| struct list_head *worklist; |
| unsigned long flags; |
| |
| debug_work_activate(work); |
| |
| spin_lock_irqsave(&gcwq->lock, flags); |
| BUG_ON(!list_empty(&work->entry)); |
| |
| cwq->nr_in_flight[cwq->work_color]++; |
| |
| if (likely(cwq->nr_active < cwq->max_active)) { |
| cwq->nr_active++; |
| worklist = &cwq->worklist; |
| } else |
| worklist = &cwq->delayed_works; |
| |
| insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color)); |
| |
| spin_unlock_irqrestore(&gcwq->lock, flags); |
| } |
| |
| /** |
| * queue_work - queue work on a workqueue |
| * @wq: workqueue to use |
| * @work: work to queue |
| * |
| * Returns 0 if @work was already on a queue, non-zero otherwise. |
| * |
| * We queue the work to the CPU on which it was submitted, but if the CPU dies |
| * it can be processed by another CPU. |
| */ |
| int queue_work(struct workqueue_struct *wq, struct work_struct *work) |
| { |
| int ret; |
| |
| ret = queue_work_on(get_cpu(), wq, work); |
| put_cpu(); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(queue_work); |
| |
| /** |
| * queue_work_on - queue work on specific cpu |
| * @cpu: CPU number to execute work on |
| * @wq: workqueue to use |
| * @work: work to queue |
| * |
| * Returns 0 if @work was already on a queue, non-zero otherwise. |
| * |
| * We queue the work to a specific CPU, the caller must ensure it |
| * can't go away. |
| */ |
| int |
| queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) |
| { |
| int ret = 0; |
| |
| if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
| __queue_work(cpu, wq, work); |
| ret = 1; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(queue_work_on); |
| |
| static void delayed_work_timer_fn(unsigned long __data) |
| { |
| struct delayed_work *dwork = (struct delayed_work *)__data; |
| struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work); |
| |
| __queue_work(smp_processor_id(), cwq->wq, &dwork->work); |
| } |
| |
| /** |
| * queue_delayed_work - queue work on a workqueue after delay |
| * @wq: workqueue to use |
| * @dwork: delayable work to queue |
| * @delay: number of jiffies to wait before queueing |
| * |
| * Returns 0 if @work was already on a queue, non-zero otherwise. |
| */ |
| int queue_delayed_work(struct workqueue_struct *wq, |
| struct delayed_work *dwork, unsigned long delay) |
| { |
| if (delay == 0) |
| return queue_work(wq, &dwork->work); |
| |
| return queue_delayed_work_on(-1, wq, dwork, delay); |
| } |
| EXPORT_SYMBOL_GPL(queue_delayed_work); |
| |
| /** |
| * queue_delayed_work_on - queue work on specific CPU after delay |
| * @cpu: CPU number to execute work on |
| * @wq: workqueue to use |
| * @dwork: work to queue |
| * @delay: number of jiffies to wait before queueing |
| * |
| * Returns 0 if @work was already on a queue, non-zero otherwise. |
| */ |
| int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
| struct delayed_work *dwork, unsigned long delay) |
| { |
| int ret = 0; |
| struct timer_list *timer = &dwork->timer; |
| struct work_struct *work = &dwork->work; |
| |
| if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
| BUG_ON(timer_pending(timer)); |
| BUG_ON(!list_empty(&work->entry)); |
| |
| timer_stats_timer_set_start_info(&dwork->timer); |
| |
| /* This stores cwq for the moment, for the timer_fn */ |
| set_wq_data(work, target_cwq(raw_smp_processor_id(), wq), 0); |
| timer->expires = jiffies + delay; |
| timer->data = (unsigned long)dwork; |
| timer->function = delayed_work_timer_fn; |
| |
| if (unlikely(cpu >= 0)) |
| add_timer_on(timer, cpu); |
| else |
| add_timer(timer); |
| ret = 1; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
| |
| /** |
| * worker_enter_idle - enter idle state |
| * @worker: worker which is entering idle state |
| * |
| * @worker is entering idle state. Update stats and idle timer if |
| * necessary. |
| * |
| * LOCKING: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void worker_enter_idle(struct worker *worker) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| |
| BUG_ON(worker->flags & WORKER_IDLE); |
| BUG_ON(!list_empty(&worker->entry) && |
| (worker->hentry.next || worker->hentry.pprev)); |
| |
| worker->flags |= WORKER_IDLE; |
| gcwq->nr_idle++; |
| |
| /* idle_list is LIFO */ |
| list_add(&worker->entry, &gcwq->idle_list); |
| |
| if (unlikely(worker->flags & WORKER_ROGUE)) |
| wake_up_all(&gcwq->trustee_wait); |
| } |
| |
| /** |
| * worker_leave_idle - leave idle state |
| * @worker: worker which is leaving idle state |
| * |
| * @worker is leaving idle state. Update stats. |
| * |
| * LOCKING: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void worker_leave_idle(struct worker *worker) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| |
| BUG_ON(!(worker->flags & WORKER_IDLE)); |
| worker->flags &= ~WORKER_IDLE; |
| gcwq->nr_idle--; |
| list_del_init(&worker->entry); |
| } |
| |
| static struct worker *alloc_worker(void) |
| { |
| struct worker *worker; |
| |
| worker = kzalloc(sizeof(*worker), GFP_KERNEL); |
| if (worker) { |
| INIT_LIST_HEAD(&worker->entry); |
| INIT_LIST_HEAD(&worker->scheduled); |
| } |
| return worker; |
| } |
| |
| /** |
| * create_worker - create a new workqueue worker |
| * @cwq: cwq the new worker will belong to |
| * @bind: whether to set affinity to @cpu or not |
| * |
| * Create a new worker which is bound to @cwq. The returned worker |
| * can be started by calling start_worker() or destroyed using |
| * destroy_worker(). |
| * |
| * CONTEXT: |
| * Might sleep. Does GFP_KERNEL allocations. |
| * |
| * RETURNS: |
| * Pointer to the newly created worker. |
| */ |
| static struct worker *create_worker(struct cpu_workqueue_struct *cwq, bool bind) |
| { |
| struct global_cwq *gcwq = cwq->gcwq; |
| int id = -1; |
| struct worker *worker = NULL; |
| |
| spin_lock_irq(&gcwq->lock); |
| while (ida_get_new(&gcwq->worker_ida, &id)) { |
| spin_unlock_irq(&gcwq->lock); |
| if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) |
| goto fail; |
| spin_lock_irq(&gcwq->lock); |
| } |
| spin_unlock_irq(&gcwq->lock); |
| |
| worker = alloc_worker(); |
| if (!worker) |
| goto fail; |
| |
| worker->gcwq = gcwq; |
| worker->cwq = cwq; |
| worker->id = id; |
| |
| worker->task = kthread_create(worker_thread, worker, "kworker/%u:%d", |
| gcwq->cpu, id); |
| if (IS_ERR(worker->task)) |
| goto fail; |
| |
| /* |
| * A rogue worker will become a regular one if CPU comes |
| * online later on. Make sure every worker has |
| * PF_THREAD_BOUND set. |
| */ |
| if (bind) |
| kthread_bind(worker->task, gcwq->cpu); |
| else |
| worker->task->flags |= PF_THREAD_BOUND; |
| |
| return worker; |
| fail: |
| if (id >= 0) { |
| spin_lock_irq(&gcwq->lock); |
| ida_remove(&gcwq->worker_ida, id); |
| spin_unlock_irq(&gcwq->lock); |
| } |
| kfree(worker); |
| return NULL; |
| } |
| |
| /** |
| * start_worker - start a newly created worker |
| * @worker: worker to start |
| * |
| * Make the gcwq aware of @worker and start it. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void start_worker(struct worker *worker) |
| { |
| worker->flags |= WORKER_STARTED; |
| worker->gcwq->nr_workers++; |
| worker_enter_idle(worker); |
| wake_up_process(worker->task); |
| } |
| |
| /** |
| * destroy_worker - destroy a workqueue worker |
| * @worker: worker to be destroyed |
| * |
| * Destroy @worker and adjust @gcwq stats accordingly. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
| */ |
| static void destroy_worker(struct worker *worker) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| int id = worker->id; |
| |
| /* sanity check frenzy */ |
| BUG_ON(worker->current_work); |
| BUG_ON(!list_empty(&worker->scheduled)); |
| |
| if (worker->flags & WORKER_STARTED) |
| gcwq->nr_workers--; |
| if (worker->flags & WORKER_IDLE) |
| gcwq->nr_idle--; |
| |
| list_del_init(&worker->entry); |
| worker->flags |= WORKER_DIE; |
| |
| spin_unlock_irq(&gcwq->lock); |
| |
| kthread_stop(worker->task); |
| kfree(worker); |
| |
| spin_lock_irq(&gcwq->lock); |
| ida_remove(&gcwq->worker_ida, id); |
| } |
| |
| /** |
| * 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); |
| |
| move_linked_works(work, &cwq->worklist, NULL); |
| 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 |
| * |
| * 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) |
| { |
| /* ignore uncolored works */ |
| if (color == WORK_NO_COLOR) |
| return; |
| |
| cwq->nr_in_flight[color]--; |
| cwq->nr_active--; |
| |
| /* one down, submit a delayed one */ |
| if (!list_empty(&cwq->delayed_works) && |
| 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 |
| * @work: work to process |
| * |
| * Process @work. This function contains all the logics necessary to |
| * process a single work including synchronization against and |
| * interaction with other workers on the same cpu, queueing and |
| * flushing. As long as context requirement is met, any worker can |
| * call this function to process a work. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
| */ |
| static void process_one_work(struct worker *worker, struct work_struct *work) |
| { |
| struct cpu_workqueue_struct *cwq = worker->cwq; |
| struct global_cwq *gcwq = cwq->gcwq; |
| struct hlist_head *bwh = busy_worker_head(gcwq, work); |
| work_func_t f = work->func; |
| int work_color; |
| #ifdef CONFIG_LOCKDEP |
| /* |
| * It is permissible to free the struct work_struct from |
| * inside the function that is called from it, this we need to |
| * take into account for lockdep too. To avoid bogus "held |
| * lock freed" warnings as well as problems when looking into |
| * work->lockdep_map, make a copy and use that here. |
| */ |
| struct lockdep_map lockdep_map = work->lockdep_map; |
| #endif |
| /* claim and process */ |
| debug_work_deactivate(work); |
| hlist_add_head(&worker->hentry, bwh); |
| worker->current_work = work; |
| work_color = get_work_color(work); |
| list_del_init(&work->entry); |
| |
| spin_unlock_irq(&gcwq->lock); |
| |
| BUG_ON(get_wq_data(work) != cwq); |
| work_clear_pending(work); |
| lock_map_acquire(&cwq->wq->lockdep_map); |
| lock_map_acquire(&lockdep_map); |
| f(work); |
| lock_map_release(&lockdep_map); |
| lock_map_release(&cwq->wq->lockdep_map); |
| |
| if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
| printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " |
| "%s/0x%08x/%d\n", |
| current->comm, preempt_count(), task_pid_nr(current)); |
| printk(KERN_ERR " last function: "); |
| print_symbol("%s\n", (unsigned long)f); |
| debug_show_held_locks(current); |
| dump_stack(); |
| } |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| /* we're done with it, release */ |
| hlist_del_init(&worker->hentry); |
| worker->current_work = NULL; |
| cwq_dec_nr_in_flight(cwq, work_color); |
| } |
| |
| /** |
| * process_scheduled_works - process scheduled works |
| * @worker: self |
| * |
| * Process all scheduled works. Please note that the scheduled list |
| * may change while processing a work, so this function repeatedly |
| * fetches a work from the top and executes it. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. |
| */ |
| static void process_scheduled_works(struct worker *worker) |
| { |
| while (!list_empty(&worker->scheduled)) { |
| struct work_struct *work = list_first_entry(&worker->scheduled, |
| struct work_struct, entry); |
| process_one_work(worker, work); |
| } |
| } |
| |
| /** |
| * worker_thread - the worker thread function |
| * @__worker: self |
| * |
| * The cwq worker thread function. |
| */ |
| static int worker_thread(void *__worker) |
| { |
| struct worker *worker = __worker; |
| struct global_cwq *gcwq = worker->gcwq; |
| struct cpu_workqueue_struct *cwq = worker->cwq; |
| |
| woke_up: |
| spin_lock_irq(&gcwq->lock); |
| |
| /* DIE can be set only while we're idle, checking here is enough */ |
| if (worker->flags & WORKER_DIE) { |
| spin_unlock_irq(&gcwq->lock); |
| return 0; |
| } |
| |
| worker_leave_idle(worker); |
| recheck: |
| /* |
| * ->scheduled list can only be filled while a worker is |
| * preparing to process a work or actually processing it. |
| * Make sure nobody diddled with it while I was sleeping. |
| */ |
| BUG_ON(!list_empty(&worker->scheduled)); |
| |
| while (!list_empty(&cwq->worklist)) { |
| struct work_struct *work = |
| list_first_entry(&cwq->worklist, |
| struct work_struct, entry); |
| |
| /* |
| * The following is a rather inefficient way to close |
| * race window against cpu hotplug operations. Will |
| * be replaced soon. |
| */ |
| if (unlikely(!(worker->flags & WORKER_ROGUE) && |
| !cpumask_equal(&worker->task->cpus_allowed, |
| get_cpu_mask(gcwq->cpu)))) { |
| spin_unlock_irq(&gcwq->lock); |
| set_cpus_allowed_ptr(worker->task, |
| get_cpu_mask(gcwq->cpu)); |
| cpu_relax(); |
| spin_lock_irq(&gcwq->lock); |
| goto recheck; |
| } |
| |
| if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
| /* optimization path, not strictly necessary */ |
| process_one_work(worker, work); |
| if (unlikely(!list_empty(&worker->scheduled))) |
| process_scheduled_works(worker); |
| } else { |
| move_linked_works(work, &worker->scheduled, NULL); |
| process_scheduled_works(worker); |
| } |
| } |
| |
| /* |
| * gcwq->lock is held and there's no work to process, sleep. |
| * Workers are woken up only while holding gcwq->lock, so |
| * setting the current state before releasing gcwq->lock is |
| * enough to prevent losing any event. |
| */ |
| worker_enter_idle(worker); |
| __set_current_state(TASK_INTERRUPTIBLE); |
| spin_unlock_irq(&gcwq->lock); |
| schedule(); |
| goto woke_up; |
| } |
| |
| struct wq_barrier { |
| struct work_struct work; |
| struct completion done; |
| }; |
| |
| static void wq_barrier_func(struct work_struct *work) |
| { |
| struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
| complete(&barr->done); |
| } |
| |
| /** |
| * insert_wq_barrier - insert a barrier work |
| * @cwq: cwq to insert barrier into |
| * @barr: wq_barrier to insert |
| * @target: target work to attach @barr to |
| * @worker: worker currently executing @target, NULL if @target is not executing |
| * |
| * @barr is linked to @target such that @barr is completed only after |
| * @target finishes execution. Please note that the ordering |
| * guarantee is observed only with respect to @target and on the local |
| * cpu. |
| * |
| * Currently, a queued barrier can't be canceled. This is because |
| * try_to_grab_pending() can't determine whether the work to be |
| * grabbed is at the head of the queue and thus can't clear LINKED |
| * flag of the previous work while there must be a valid next work |
| * after a work with LINKED flag set. |
| * |
| * Note that when @worker is non-NULL, @target may be modified |
| * underneath us, so we can't reliably determine cwq from @target. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
| struct wq_barrier *barr, |
| struct work_struct *target, struct worker *worker) |
| { |
| struct list_head *head; |
| unsigned int linked = 0; |
| |
| /* |
| * debugobject calls are safe here even with gcwq->lock locked |
| * as we know for sure that this will not trigger any of the |
| * checks and call back into the fixup functions where we |
| * might deadlock. |
| */ |
| INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); |
| __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
| init_completion(&barr->done); |
| |
| /* |
| * If @target is currently being executed, schedule the |
| * barrier to the worker; otherwise, put it after @target. |
| */ |
| if (worker) |
| head = worker->scheduled.next; |
| else { |
| unsigned long *bits = work_data_bits(target); |
| |
| head = target->entry.next; |
| /* there can already be other linked works, inherit and set */ |
| linked = *bits & WORK_STRUCT_LINKED; |
| __set_bit(WORK_STRUCT_LINKED_BIT, bits); |
| } |
| |
| debug_work_activate(&barr->work); |
| insert_work(cwq, &barr->work, head, |
| work_color_to_flags(WORK_NO_COLOR) | linked); |
| } |
| |
| /** |
| * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing |
| * @wq: workqueue being flushed |
| * @flush_color: new flush color, < 0 for no-op |
| * @work_color: new work color, < 0 for no-op |
| * |
| * Prepare cwqs for workqueue flushing. |
| * |
| * If @flush_color is non-negative, flush_color on all cwqs should be |
| * -1. If no cwq has in-flight commands at the specified color, all |
| * cwq->flush_color's stay at -1 and %false is returned. If any cwq |
| * has in flight commands, its cwq->flush_color is set to |
| * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq |
| * wakeup logic is armed and %true is returned. |
| * |
| * The caller should have initialized @wq->first_flusher prior to |
| * calling this function with non-negative @flush_color. If |
| * @flush_color is negative, no flush color update is done and %false |
| * is returned. |
| * |
| * If @work_color is non-negative, all cwqs should have the same |
| * work_color which is previous to @work_color and all will be |
| * advanced to @work_color. |
| * |
| * CONTEXT: |
| * mutex_lock(wq->flush_mutex). |
| * |
| * RETURNS: |
| * %true if @flush_color >= 0 and there's something to flush. %false |
| * otherwise. |
| */ |
| static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, |
| int flush_color, int work_color) |
| { |
| bool wait = false; |
| unsigned int cpu; |
| |
| if (flush_color >= 0) { |
| BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); |
| atomic_set(&wq->nr_cwqs_to_flush, 1); |
| } |
| |
| for_each_possible_cpu(cpu) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| struct global_cwq *gcwq = cwq->gcwq; |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| if (flush_color >= 0) { |
| BUG_ON(cwq->flush_color != -1); |
| |
| if (cwq->nr_in_flight[flush_color]) { |
| cwq->flush_color = flush_color; |
| atomic_inc(&wq->nr_cwqs_to_flush); |
| wait = true; |
| } |
| } |
| |
| if (work_color >= 0) { |
| BUG_ON(work_color != work_next_color(cwq->work_color)); |
| cwq->work_color = work_color; |
| } |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) |
| complete(&wq->first_flusher->done); |
| |
| return wait; |
| } |
| |
| /** |
| * flush_workqueue - ensure that any scheduled work has run to completion. |
| * @wq: workqueue to flush |
| * |
| * Forces execution of the workqueue and blocks until its completion. |
| * This is typically used in driver shutdown handlers. |
| * |
| * We sleep until all works which were queued on entry have been handled, |
| * but we are not livelocked by new incoming ones. |
| */ |
| void flush_workqueue(struct workqueue_struct *wq) |
| { |
| struct wq_flusher this_flusher = { |
| .list = LIST_HEAD_INIT(this_flusher.list), |
| .flush_color = -1, |
| .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), |
| }; |
| int next_color; |
| |
| lock_map_acquire(&wq->lockdep_map); |
| lock_map_release(&wq->lockdep_map); |
| |
| mutex_lock(&wq->flush_mutex); |
| |
| /* |
| * Start-to-wait phase |
| */ |
| next_color = work_next_color(wq->work_color); |
| |
| if (next_color != wq->flush_color) { |
| /* |
| * Color space is not full. The current work_color |
| * becomes our flush_color and work_color is advanced |
| * by one. |
| */ |
| BUG_ON(!list_empty(&wq->flusher_overflow)); |
| this_flusher.flush_color = wq->work_color; |
| wq->work_color = next_color; |
| |
| if (!wq->first_flusher) { |
| /* no flush in progress, become the first flusher */ |
| BUG_ON(wq->flush_color != this_flusher.flush_color); |
| |
| wq->first_flusher = &this_flusher; |
| |
| if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, |
| wq->work_color)) { |
| /* nothing to flush, done */ |
| wq->flush_color = next_color; |
| wq->first_flusher = NULL; |
| goto out_unlock; |
| } |
| } else { |
| /* wait in queue */ |
| BUG_ON(wq->flush_color == this_flusher.flush_color); |
| list_add_tail(&this_flusher.list, &wq->flusher_queue); |
| flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
| } |
| } else { |
| /* |
| * Oops, color space is full, wait on overflow queue. |
| * The next flush completion will assign us |
| * flush_color and transfer to flusher_queue. |
| */ |
| list_add_tail(&this_flusher.list, &wq->flusher_overflow); |
| } |
| |
| mutex_unlock(&wq->flush_mutex); |
| |
| wait_for_completion(&this_flusher.done); |
| |
| /* |
| * Wake-up-and-cascade phase |
| * |
| * First flushers are responsible for cascading flushes and |
| * handling overflow. Non-first flushers can simply return. |
| */ |
| if (wq->first_flusher != &this_flusher) |
| return; |
| |
| mutex_lock(&wq->flush_mutex); |
| |
| wq->first_flusher = NULL; |
| |
| BUG_ON(!list_empty(&this_flusher.list)); |
| BUG_ON(wq->flush_color != this_flusher.flush_color); |
| |
| while (true) { |
| struct wq_flusher *next, *tmp; |
| |
| /* complete all the flushers sharing the current flush color */ |
| list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
| if (next->flush_color != wq->flush_color) |
| break; |
| list_del_init(&next->list); |
| complete(&next->done); |
| } |
| |
| BUG_ON(!list_empty(&wq->flusher_overflow) && |
| wq->flush_color != work_next_color(wq->work_color)); |
| |
| /* this flush_color is finished, advance by one */ |
| wq->flush_color = work_next_color(wq->flush_color); |
| |
| /* one color has been freed, handle overflow queue */ |
| if (!list_empty(&wq->flusher_overflow)) { |
| /* |
| * Assign the same color to all overflowed |
| * flushers, advance work_color and append to |
| * flusher_queue. This is the start-to-wait |
| * phase for these overflowed flushers. |
| */ |
| list_for_each_entry(tmp, &wq->flusher_overflow, list) |
| tmp->flush_color = wq->work_color; |
| |
| wq->work_color = work_next_color(wq->work_color); |
| |
| list_splice_tail_init(&wq->flusher_overflow, |
| &wq->flusher_queue); |
| flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
| } |
| |
| if (list_empty(&wq->flusher_queue)) { |
| BUG_ON(wq->flush_color != wq->work_color); |
| break; |
| } |
| |
| /* |
| * Need to flush more colors. Make the next flusher |
| * the new first flusher and arm cwqs. |
| */ |
| BUG_ON(wq->flush_color == wq->work_color); |
| BUG_ON(wq->flush_color != next->flush_color); |
| |
| list_del_init(&next->list); |
| wq->first_flusher = next; |
| |
| if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) |
| break; |
| |
| /* |
| * Meh... this color is already done, clear first |
| * flusher and repeat cascading. |
| */ |
| wq->first_flusher = NULL; |
| } |
| |
| out_unlock: |
| mutex_unlock(&wq->flush_mutex); |
| } |
| EXPORT_SYMBOL_GPL(flush_workqueue); |
| |
| /** |
| * flush_work - block until a work_struct's callback has terminated |
| * @work: the work which is to be flushed |
| * |
| * Returns false if @work has already terminated. |
| * |
| * It is expected that, prior to calling flush_work(), the caller has |
| * arranged for the work to not be requeued, otherwise it doesn't make |
| * sense to use this function. |
| */ |
| int flush_work(struct work_struct *work) |
| { |
| struct worker *worker = NULL; |
| struct cpu_workqueue_struct *cwq; |
| struct global_cwq *gcwq; |
| struct wq_barrier barr; |
| |
| might_sleep(); |
| cwq = get_wq_data(work); |
| if (!cwq) |
| return 0; |
| gcwq = cwq->gcwq; |
| |
| lock_map_acquire(&cwq->wq->lockdep_map); |
| lock_map_release(&cwq->wq->lockdep_map); |
| |
| spin_lock_irq(&gcwq->lock); |
| if (!list_empty(&work->entry)) { |
| /* |
| * See the comment near try_to_grab_pending()->smp_rmb(). |
| * If it was re-queued under us we are not going to wait. |
| */ |
| smp_rmb(); |
| if (unlikely(cwq != get_wq_data(work))) |
| goto already_gone; |
| } else { |
| if (cwq->worker && cwq->worker->current_work == work) |
| worker = cwq->worker; |
| if (!worker) |
| goto already_gone; |
| } |
| |
| insert_wq_barrier(cwq, &barr, work, worker); |
| spin_unlock_irq(&gcwq->lock); |
| wait_for_completion(&barr.done); |
| destroy_work_on_stack(&barr.work); |
| return 1; |
| already_gone: |
| spin_unlock_irq(&gcwq->lock); |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(flush_work); |
| |
| /* |
| * 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; |
| struct cpu_workqueue_struct *cwq; |
| 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. |
| */ |
| |
| cwq = get_wq_data(work); |
| if (!cwq) |
| return ret; |
| gcwq = cwq->gcwq; |
| |
| spin_lock_irq(&gcwq->lock); |
| if (!list_empty(&work->entry)) { |
| /* |
| * This work is queued, but perhaps we locked the wrong cwq. |
| * In that case we must see the new value after rmb(), see |
| * insert_work()->wmb(). |
| */ |
| smp_rmb(); |
| if (cwq == get_wq_data(work)) { |
| debug_work_deactivate(work); |
| list_del_init(&work->entry); |
| cwq_dec_nr_in_flight(cwq, get_work_color(work)); |
| ret = 1; |
| } |
| } |
| spin_unlock_irq(&gcwq->lock); |
| |
| return ret; |
| } |
| |
| static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq, |
| struct work_struct *work) |
| { |
| struct global_cwq *gcwq = cwq->gcwq; |
| struct wq_barrier barr; |
| struct worker *worker; |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| worker = NULL; |
| if (unlikely(cwq->worker && cwq->worker->current_work == work)) { |
| worker = cwq->worker; |
| insert_wq_barrier(cwq, &barr, work, worker); |
| } |
| |
| spin_unlock_irq(&gcwq->lock); |
| |
| if (unlikely(worker)) { |
| wait_for_completion(&barr.done); |
| destroy_work_on_stack(&barr.work); |
| } |
| } |
| |
| static void wait_on_work(struct work_struct *work) |
| { |
| struct cpu_workqueue_struct *cwq; |
| struct workqueue_struct *wq; |
| int cpu; |
| |
| might_sleep(); |
| |
| lock_map_acquire(&work->lockdep_map); |
| lock_map_release(&work->lockdep_map); |
| |
| cwq = get_wq_data(work); |
| if (!cwq) |
| return; |
| |
| wq = cwq->wq; |
| |
| for_each_possible_cpu(cpu) |
| wait_on_cpu_work(get_cwq(cpu, wq), work); |
| } |
| |
| static int __cancel_work_timer(struct work_struct *work, |
| struct timer_list* timer) |
| { |
| int ret; |
| |
| do { |
| ret = (timer && likely(del_timer(timer))); |
| if (!ret) |
| ret = try_to_grab_pending(work); |
| wait_on_work(work); |
| } while (unlikely(ret < 0)); |
| |
| clear_wq_data(work); |
| return ret; |
| } |
| |
| /** |
| * cancel_work_sync - block until a work_struct's callback has terminated |
| * @work: the work which is to be flushed |
| * |
| * Returns true if @work was pending. |
| * |
| * cancel_work_sync() will cancel the work if it is queued. If the work's |
| * callback appears to be running, cancel_work_sync() will block until it |
| * has completed. |
| * |
| * It is possible to use this function if the work re-queues itself. It can |
| * cancel the work even if it migrates to another workqueue, however in that |
| * case it only guarantees that work->func() has completed on the last queued |
| * workqueue. |
| * |
| * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not |
| * pending, otherwise it goes into a busy-wait loop until the timer expires. |
| * |
| * The caller must ensure that workqueue_struct on which this work was last |
| * queued can't be destroyed before this function returns. |
| */ |
| int cancel_work_sync(struct work_struct *work) |
| { |
| return __cancel_work_timer(work, NULL); |
| } |
| EXPORT_SYMBOL_GPL(cancel_work_sync); |
| |
| /** |
| * cancel_delayed_work_sync - reliably kill off a delayed work. |
| * @dwork: the delayed work struct |
| * |
| * Returns true if @dwork was pending. |
| * |
| * It is possible to use this function if @dwork rearms itself via queue_work() |
| * or queue_delayed_work(). See also the comment for cancel_work_sync(). |
| */ |
| int cancel_delayed_work_sync(struct delayed_work *dwork) |
| { |
| return __cancel_work_timer(&dwork->work, &dwork->timer); |
| } |
| EXPORT_SYMBOL(cancel_delayed_work_sync); |
| |
| static struct workqueue_struct *keventd_wq __read_mostly; |
| |
| /** |
| * schedule_work - put work task in global workqueue |
| * @work: job to be done |
| * |
| * Returns zero if @work was already on the kernel-global workqueue and |
| * non-zero otherwise. |
| * |
| * This puts a job in the kernel-global workqueue if it was not already |
| * queued and leaves it in the same position on the kernel-global |
| * workqueue otherwise. |
| */ |
| int schedule_work(struct work_struct *work) |
| { |
| return queue_work(keventd_wq, work); |
| } |
| EXPORT_SYMBOL(schedule_work); |
| |
| /* |
| * schedule_work_on - put work task on a specific cpu |
| * @cpu: cpu to put the work task on |
| * @work: job to be done |
| * |
| * This puts a job on a specific cpu |
| */ |
| int schedule_work_on(int cpu, struct work_struct *work) |
| { |
| return queue_work_on(cpu, keventd_wq, work); |
| } |
| EXPORT_SYMBOL(schedule_work_on); |
| |
| /** |
| * schedule_delayed_work - put work task in global workqueue after delay |
| * @dwork: job to be done |
| * @delay: number of jiffies to wait or 0 for immediate execution |
| * |
| * After waiting for a given time this puts a job in the kernel-global |
| * workqueue. |
| */ |
| int schedule_delayed_work(struct delayed_work *dwork, |
| unsigned long delay) |
| { |
| return queue_delayed_work(keventd_wq, dwork, delay); |
| } |
| EXPORT_SYMBOL(schedule_delayed_work); |
| |
| /** |
| * flush_delayed_work - block until a dwork_struct's callback has terminated |
| * @dwork: the delayed work which is to be flushed |
| * |
| * Any timeout is cancelled, and any pending work is run immediately. |
| */ |
| void flush_delayed_work(struct delayed_work *dwork) |
| { |
| if (del_timer_sync(&dwork->timer)) { |
| __queue_work(get_cpu(), get_wq_data(&dwork->work)->wq, |
| &dwork->work); |
| put_cpu(); |
| } |
| flush_work(&dwork->work); |
| } |
| EXPORT_SYMBOL(flush_delayed_work); |
| |
| /** |
| * schedule_delayed_work_on - queue work in global workqueue on CPU after delay |
| * @cpu: cpu to use |
| * @dwork: job to be done |
| * @delay: number of jiffies to wait |
| * |
| * After waiting for a given time this puts a job in the kernel-global |
| * workqueue on the specified CPU. |
| */ |
| int schedule_delayed_work_on(int cpu, |
| struct delayed_work *dwork, unsigned long delay) |
| { |
| return queue_delayed_work_on(cpu, keventd_wq, dwork, delay); |
| } |
| EXPORT_SYMBOL(schedule_delayed_work_on); |
| |
| /** |
| * schedule_on_each_cpu - call a function on each online CPU from keventd |
| * @func: the function to call |
| * |
| * Returns zero on success. |
| * Returns -ve errno on failure. |
| * |
| * schedule_on_each_cpu() is very slow. |
| */ |
| int schedule_on_each_cpu(work_func_t func) |
| { |
| int cpu; |
| int orig = -1; |
| struct work_struct *works; |
| |
| works = alloc_percpu(struct work_struct); |
| if (!works) |
| return -ENOMEM; |
| |
| get_online_cpus(); |
| |
| /* |
| * When running in keventd don't schedule a work item on |
| * itself. Can just call directly because the work queue is |
| * already bound. This also is faster. |
| */ |
| if (current_is_keventd()) |
| orig = raw_smp_processor_id(); |
| |
| for_each_online_cpu(cpu) { |
| struct work_struct *work = per_cpu_ptr(works, cpu); |
| |
| INIT_WORK(work, func); |
| if (cpu != orig) |
| schedule_work_on(cpu, work); |
| } |
| if (orig >= 0) |
| func(per_cpu_ptr(works, orig)); |
| |
| for_each_online_cpu(cpu) |
| flush_work(per_cpu_ptr(works, cpu)); |
| |
| put_online_cpus(); |
| free_percpu(works); |
| return 0; |
| } |
| |
| /** |
| * flush_scheduled_work - ensure that any scheduled work has run to completion. |
| * |
| * Forces execution of the kernel-global workqueue and blocks until its |
| * completion. |
| * |
| * Think twice before calling this function! It's very easy to get into |
| * trouble if you don't take great care. Either of the following situations |
| * will lead to deadlock: |
| * |
| * One of the work items currently on the workqueue needs to acquire |
| * a lock held by your code or its caller. |
| * |
| * Your code is running in the context of a work routine. |
| * |
| * They will be detected by lockdep when they occur, but the first might not |
| * occur very often. It depends on what work items are on the workqueue and |
| * what locks they need, which you have no control over. |
| * |
| * In most situations flushing the entire workqueue is overkill; you merely |
| * need to know that a particular work item isn't queued and isn't running. |
| * In such cases you should use cancel_delayed_work_sync() or |
| * cancel_work_sync() instead. |
| */ |
| void flush_scheduled_work(void) |
| { |
| flush_workqueue(keventd_wq); |
| } |
| EXPORT_SYMBOL(flush_scheduled_work); |
| |
| /** |
| * execute_in_process_context - reliably execute the routine with user context |
| * @fn: the function to execute |
| * @ew: guaranteed storage for the execute work structure (must |
| * be available when the work executes) |
| * |
| * Executes the function immediately if process context is available, |
| * otherwise schedules the function for delayed execution. |
| * |
| * Returns: 0 - function was executed |
| * 1 - function was scheduled for execution |
| */ |
| int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
| { |
| if (!in_interrupt()) { |
| fn(&ew->work); |
| return 0; |
| } |
| |
| INIT_WORK(&ew->work, fn); |
| schedule_work(&ew->work); |
| |
| return 1; |
| } |
| EXPORT_SYMBOL_GPL(execute_in_process_context); |
| |
| int keventd_up(void) |
| { |
| return keventd_wq != NULL; |
| } |
| |
| int current_is_keventd(void) |
| { |
| struct cpu_workqueue_struct *cwq; |
| int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */ |
| int ret = 0; |
| |
| BUG_ON(!keventd_wq); |
| |
| cwq = get_cwq(cpu, keventd_wq); |
| if (current == cwq->worker->task) |
| ret = 1; |
| |
| return ret; |
| |
| } |
| |
| static struct cpu_workqueue_struct *alloc_cwqs(void) |
| { |
| /* |
| * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. |
| * Make sure that the alignment isn't lower than that of |
| * unsigned long long. |
| */ |
| const size_t size = sizeof(struct cpu_workqueue_struct); |
| const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, |
| __alignof__(unsigned long long)); |
| struct cpu_workqueue_struct *cwqs; |
| #ifndef CONFIG_SMP |
| void *ptr; |
| |
| /* |
| * On UP, percpu allocator doesn't honor alignment parameter |
| * and simply uses arch-dependent default. Allocate enough |
| * room to align cwq and put an extra pointer at the end |
| * pointing back to the originally allocated pointer which |
| * will be used for free. |
| * |
| * FIXME: This really belongs to UP percpu code. Update UP |
| * percpu code to honor alignment and remove this ugliness. |
| */ |
| ptr = __alloc_percpu(size + align + sizeof(void *), 1); |
| cwqs = PTR_ALIGN(ptr, align); |
| *(void **)per_cpu_ptr(cwqs + 1, 0) = ptr; |
| #else |
| /* On SMP, percpu allocator can do it itself */ |
| cwqs = __alloc_percpu(size, align); |
| #endif |
| /* just in case, make sure it's actually aligned */ |
| BUG_ON(!IS_ALIGNED((unsigned long)cwqs, align)); |
| return cwqs; |
| } |
| |
| static void free_cwqs(struct cpu_workqueue_struct *cwqs) |
| { |
| #ifndef CONFIG_SMP |
| /* on UP, the pointer to free is stored right after the cwq */ |
| if (cwqs) |
| free_percpu(*(void **)per_cpu_ptr(cwqs + 1, 0)); |
| #else |
| free_percpu(cwqs); |
| #endif |
| } |
| |
| struct workqueue_struct *__create_workqueue_key(const char *name, |
| unsigned int flags, |
| int max_active, |
| struct lock_class_key *key, |
| const char *lock_name) |
| { |
| bool singlethread = flags & WQ_SINGLE_THREAD; |
| struct workqueue_struct *wq; |
| bool failed = false; |
| unsigned int cpu; |
| |
| max_active = clamp_val(max_active, 1, INT_MAX); |
| |
| wq = kzalloc(sizeof(*wq), GFP_KERNEL); |
| if (!wq) |
| goto err; |
| |
| wq->cpu_wq = alloc_cwqs(); |
| if (!wq->cpu_wq) |
| goto err; |
| |
| wq->flags = flags; |
| wq->saved_max_active = max_active; |
| mutex_init(&wq->flush_mutex); |
| atomic_set(&wq->nr_cwqs_to_flush, 0); |
| INIT_LIST_HEAD(&wq->flusher_queue); |
| INIT_LIST_HEAD(&wq->flusher_overflow); |
| wq->name = name; |
| lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
| INIT_LIST_HEAD(&wq->list); |
| |
| cpu_maps_update_begin(); |
| /* |
| * We must initialize cwqs for each possible cpu even if we |
| * are going to call destroy_workqueue() finally. Otherwise |
| * cpu_up() can hit the uninitialized cwq once we drop the |
| * lock. |
| */ |
| for_each_possible_cpu(cpu) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| |
| BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); |
| cwq->gcwq = gcwq; |
| cwq->wq = wq; |
| cwq->flush_color = -1; |
| cwq->max_active = max_active; |
| INIT_LIST_HEAD(&cwq->worklist); |
| INIT_LIST_HEAD(&cwq->delayed_works); |
| |
| if (failed) |
| continue; |
| cwq->worker = create_worker(cwq, |
| cpu_online(cpu) && !singlethread); |
| if (cwq->worker) |
| start_worker(cwq->worker); |
| else |
| failed = true; |
| } |
| |
| /* |
| * workqueue_lock protects global freeze state and workqueues |
| * list. Grab it, set max_active accordingly and add the new |
| * workqueue to workqueues list. |
| */ |
| spin_lock(&workqueue_lock); |
| |
| if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) |
| for_each_possible_cpu(cpu) |
| get_cwq(cpu, wq)->max_active = 0; |
| |
| list_add(&wq->list, &workqueues); |
| |
| spin_unlock(&workqueue_lock); |
| |
| cpu_maps_update_done(); |
| |
| if (failed) { |
| destroy_workqueue(wq); |
| wq = NULL; |
| } |
| return wq; |
| err: |
| if (wq) { |
| free_cwqs(wq->cpu_wq); |
| kfree(wq); |
| } |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(__create_workqueue_key); |
| |
| /** |
| * destroy_workqueue - safely terminate a workqueue |
| * @wq: target workqueue |
| * |
| * Safely destroy a workqueue. All work currently pending will be done first. |
| */ |
| void destroy_workqueue(struct workqueue_struct *wq) |
| { |
| unsigned int cpu; |
| |
| flush_workqueue(wq); |
| |
| /* |
| * wq list is used to freeze wq, remove from list after |
| * flushing is complete in case freeze races us. |
| */ |
| cpu_maps_update_begin(); |
| spin_lock(&workqueue_lock); |
| list_del(&wq->list); |
| spin_unlock(&workqueue_lock); |
| cpu_maps_update_done(); |
| |
| for_each_possible_cpu(cpu) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| int i; |
| |
| if (cwq->worker) { |
| spin_lock_irq(&cwq->gcwq->lock); |
| destroy_worker(cwq->worker); |
| cwq->worker = NULL; |
| spin_unlock_irq(&cwq->gcwq->lock); |
| } |
| |
| for (i = 0; i < WORK_NR_COLORS; i++) |
| BUG_ON(cwq->nr_in_flight[i]); |
| BUG_ON(cwq->nr_active); |
| BUG_ON(!list_empty(&cwq->delayed_works)); |
| } |
| |
| free_cwqs(wq->cpu_wq); |
| kfree(wq); |
| } |
| EXPORT_SYMBOL_GPL(destroy_workqueue); |
| |
| /* |
| * CPU hotplug. |
| * |
| * CPU hotplug is implemented by allowing cwqs to be detached from |
| * CPU, running with unbound workers and allowing them to be |
| * reattached later if the cpu comes back online. A separate thread |
| * is created to govern cwqs in such state and is called the trustee. |
| * |
| * Trustee states and their descriptions. |
| * |
| * START Command state used on startup. On CPU_DOWN_PREPARE, a |
| * new trustee is started with this state. |
| * |
| * IN_CHARGE Once started, trustee will enter this state after |
| * making all existing workers rogue. DOWN_PREPARE waits |
| * for trustee to enter this state. After reaching |
| * IN_CHARGE, trustee tries to execute the pending |
| * worklist until it's empty and the state is set to |
| * BUTCHER, or the state is set to RELEASE. |
| * |
| * BUTCHER Command state which is set by the cpu callback after |
| * the cpu has went down. Once this state is set trustee |
| * knows that there will be no new works on the worklist |
| * and once the worklist is empty it can proceed to |
| * killing idle workers. |
| * |
| * RELEASE Command state which is set by the cpu callback if the |
| * cpu down has been canceled or it has come online |
| * again. After recognizing this state, trustee stops |
| * trying to drain or butcher and transits to DONE. |
| * |
| * DONE Trustee will enter this state after BUTCHER or RELEASE |
| * is complete. |
| * |
| * trustee CPU draining |
| * took over down complete |
| * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE |
| * | | ^ |
| * | CPU is back online v return workers | |
| * ----------------> RELEASE -------------- |
| */ |
| |
| /** |
| * trustee_wait_event_timeout - timed event wait for trustee |
| * @cond: condition to wait for |
| * @timeout: timeout in jiffies |
| * |
| * wait_event_timeout() for trustee to use. Handles locking and |
| * checks for RELEASE request. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. To be used by trustee. |
| * |
| * RETURNS: |
| * Positive indicating left time if @cond is satisfied, 0 if timed |
| * out, -1 if canceled. |
| */ |
| #define trustee_wait_event_timeout(cond, timeout) ({ \ |
| long __ret = (timeout); \ |
| while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ |
| __ret) { \ |
| spin_unlock_irq(&gcwq->lock); \ |
| __wait_event_timeout(gcwq->trustee_wait, (cond) || \ |
| (gcwq->trustee_state == TRUSTEE_RELEASE), \ |
| __ret); \ |
| spin_lock_irq(&gcwq->lock); \ |
| } \ |
| gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ |
| }) |
| |
| /** |
| * trustee_wait_event - event wait for trustee |
| * @cond: condition to wait for |
| * |
| * wait_event() for trustee to use. Automatically handles locking and |
| * checks for CANCEL request. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. To be used by trustee. |
| * |
| * RETURNS: |
| * 0 if @cond is satisfied, -1 if canceled. |
| */ |
| #define trustee_wait_event(cond) ({ \ |
| long __ret1; \ |
| __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ |
| __ret1 < 0 ? -1 : 0; \ |
| }) |
| |
| static int __cpuinit trustee_thread(void *__gcwq) |
| { |
| struct global_cwq *gcwq = __gcwq; |
| struct worker *worker; |
| struct hlist_node *pos; |
| int i; |
| |
| BUG_ON(gcwq->cpu != smp_processor_id()); |
| |
| spin_lock_irq(&gcwq->lock); |
| /* |
| * Make all multithread workers rogue. Trustee must be bound |
| * to the target cpu and can't be cancelled. |
| */ |
| BUG_ON(gcwq->cpu != smp_processor_id()); |
| |
| list_for_each_entry(worker, &gcwq->idle_list, entry) |
| if (!(worker->cwq->wq->flags & WQ_SINGLE_THREAD)) |
| worker->flags |= WORKER_ROGUE; |
| |
| for_each_busy_worker(worker, i, pos, gcwq) |
| if (!(worker->cwq->wq->flags & WQ_SINGLE_THREAD)) |
| worker->flags |= WORKER_ROGUE; |
| |
| /* |
| * We're now in charge. Notify and proceed to drain. We need |
| * to keep the gcwq running during the whole CPU down |
| * procedure as other cpu hotunplug callbacks may need to |
| * flush currently running tasks. |
| */ |
| gcwq->trustee_state = TRUSTEE_IN_CHARGE; |
| wake_up_all(&gcwq->trustee_wait); |
| |
| /* |
| * The original cpu is in the process of dying and may go away |
| * anytime now. When that happens, we and all workers would |
| * be migrated to other cpus. Try draining any left work. |
| * Note that if the gcwq is frozen, there may be frozen works |
| * in freezeable cwqs. Don't declare completion while frozen. |
| */ |
| while (gcwq->nr_workers != gcwq->nr_idle || |
| gcwq->flags & GCWQ_FREEZING || |
| gcwq->trustee_state == TRUSTEE_IN_CHARGE) { |
| /* give a breather */ |
| if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) |
| break; |
| } |
| |
| /* notify completion */ |
| gcwq->trustee = NULL; |
| gcwq->trustee_state = TRUSTEE_DONE; |
| wake_up_all(&gcwq->trustee_wait); |
| spin_unlock_irq(&gcwq->lock); |
| return 0; |
| } |
| |
| /** |
| * wait_trustee_state - wait for trustee to enter the specified state |
| * @gcwq: gcwq the trustee of interest belongs to |
| * @state: target state to wait for |
| * |
| * Wait for the trustee to reach @state. DONE is already matched. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. To be used by cpu_callback. |
| */ |
| static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) |
| { |
| if (!(gcwq->trustee_state == state || |
| gcwq->trustee_state == TRUSTEE_DONE)) { |
| spin_unlock_irq(&gcwq->lock); |
| __wait_event(gcwq->trustee_wait, |
| gcwq->trustee_state == state || |
| gcwq->trustee_state == TRUSTEE_DONE); |
| spin_lock_irq(&gcwq->lock); |
| } |
| } |
| |
| static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, |
| unsigned long action, |
| void *hcpu) |
| { |
| unsigned int cpu = (unsigned long)hcpu; |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| struct task_struct *new_trustee = NULL; |
| struct worker *worker; |
| struct hlist_node *pos; |
| unsigned long flags; |
| int i; |
| |
| action &= ~CPU_TASKS_FROZEN; |
| |
| switch (action) { |
| case CPU_DOWN_PREPARE: |
| new_trustee = kthread_create(trustee_thread, gcwq, |
| "workqueue_trustee/%d\n", cpu); |
| if (IS_ERR(new_trustee)) |
| return notifier_from_errno(PTR_ERR(new_trustee)); |
| kthread_bind(new_trustee, cpu); |
| } |
| |
| /* some are called w/ irq disabled, don't disturb irq status */ |
| spin_lock_irqsave(&gcwq->lock, flags); |
| |
| switch (action) { |
| case CPU_DOWN_PREPARE: |
| /* initialize trustee and tell it to acquire the gcwq */ |
| BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); |
| gcwq->trustee = new_trustee; |
| gcwq->trustee_state = TRUSTEE_START; |
| wake_up_process(gcwq->trustee); |
| wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); |
| break; |
| |
| case CPU_POST_DEAD: |
| gcwq->trustee_state = TRUSTEE_BUTCHER; |
| break; |
| |
| case CPU_DOWN_FAILED: |
| case CPU_ONLINE: |
| if (gcwq->trustee_state != TRUSTEE_DONE) { |
| gcwq->trustee_state = TRUSTEE_RELEASE; |
| wake_up_process(gcwq->trustee); |
| wait_trustee_state(gcwq, TRUSTEE_DONE); |
| } |
| |
| /* clear ROGUE from all multithread workers */ |
| list_for_each_entry(worker, &gcwq->idle_list, entry) |
| if (!(worker->cwq->wq->flags & WQ_SINGLE_THREAD)) |
| worker->flags &= ~WORKER_ROGUE; |
| |
| for_each_busy_worker(worker, i, pos, gcwq) |
| if (!(worker->cwq->wq->flags & WQ_SINGLE_THREAD)) |
| worker->flags &= ~WORKER_ROGUE; |
| break; |
| } |
| |
| spin_unlock_irqrestore(&gcwq->lock, flags); |
| |
| return notifier_from_errno(0); |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| struct work_for_cpu { |
| struct completion completion; |
| long (*fn)(void *); |
| void *arg; |
| long ret; |
| }; |
| |
| static int do_work_for_cpu(void *_wfc) |
| { |
| struct work_for_cpu *wfc = _wfc; |
| wfc->ret = wfc->fn(wfc->arg); |
| complete(&wfc->completion); |
| return 0; |
| } |
| |
| /** |
| * work_on_cpu - run a function in user context on a particular cpu |
| * @cpu: the cpu to run on |
| * @fn: the function to run |
| * @arg: the function arg |
| * |
| * This will return the value @fn returns. |
| * It is up to the caller to ensure that the cpu doesn't go offline. |
| * The caller must not hold any locks which would prevent @fn from completing. |
| */ |
| long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) |
| { |
| struct task_struct *sub_thread; |
| struct work_for_cpu wfc = { |
| .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), |
| .fn = fn, |
| .arg = arg, |
| }; |
| |
| sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); |
| if (IS_ERR(sub_thread)) |
| return PTR_ERR(sub_thread); |
| kthread_bind(sub_thread, cpu); |
| wake_up_process(sub_thread); |
| wait_for_completion(&wfc.completion); |
| return wfc.ret; |
| } |
| EXPORT_SYMBOL_GPL(work_on_cpu); |
| #endif /* CONFIG_SMP */ |
| |
| #ifdef CONFIG_FREEZER |
| |
| /** |
| * freeze_workqueues_begin - begin freezing workqueues |
| * |
| * Start freezing workqueues. After this function returns, all |
| * freezeable workqueues will queue new works to their frozen_works |
| * list instead of the cwq ones. |
| * |
| * CONTEXT: |
| * Grabs and releases workqueue_lock and gcwq->lock's. |
| */ |
| void freeze_workqueues_begin(void) |
| { |
| struct workqueue_struct *wq; |
| unsigned int cpu; |
| |
| spin_lock(&workqueue_lock); |
| |
| BUG_ON(workqueue_freezing); |
| workqueue_freezing = true; |
| |
| for_each_possible_cpu(cpu) { |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| BUG_ON(gcwq->flags & GCWQ_FREEZING); |
| gcwq->flags |= GCWQ_FREEZING; |
| |
| list_for_each_entry(wq, &workqueues, list) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| |
| if (wq->flags & WQ_FREEZEABLE) |
| cwq->max_active = 0; |
| } |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| spin_unlock(&workqueue_lock); |
| } |
| |
| /** |
| * freeze_workqueues_busy - are freezeable workqueues still busy? |
| * |
| * Check whether freezing is complete. This function must be called |
| * between freeze_workqueues_begin() and thaw_workqueues(). |
| * |
| * CONTEXT: |
| * Grabs and releases workqueue_lock. |
| * |
| * RETURNS: |
| * %true if some freezeable workqueues are still busy. %false if |
| * freezing is complete. |
| */ |
| bool freeze_workqueues_busy(void) |
| { |
| struct workqueue_struct *wq; |
| unsigned int cpu; |
| bool busy = false; |
| |
| spin_lock(&workqueue_lock); |
| |
| BUG_ON(!workqueue_freezing); |
| |
| for_each_possible_cpu(cpu) { |
| /* |
| * nr_active is monotonically decreasing. It's safe |
| * to peek without lock. |
| */ |
| list_for_each_entry(wq, &workqueues, list) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| |
| if (!(wq->flags & WQ_FREEZEABLE)) |
| continue; |
| |
| BUG_ON(cwq->nr_active < 0); |
| if (cwq->nr_active) { |
| busy = true; |
| goto out_unlock; |
| } |
| } |
| } |
| out_unlock: |
| spin_unlock(&workqueue_lock); |
| return busy; |
| } |
| |
| /** |
| * thaw_workqueues - thaw workqueues |
| * |
| * Thaw workqueues. Normal queueing is restored and all collected |
| * frozen works are transferred to their respective cwq worklists. |
| * |
| * CONTEXT: |
| * Grabs and releases workqueue_lock and gcwq->lock's. |
| */ |
| void thaw_workqueues(void) |
| { |
| struct workqueue_struct *wq; |
| unsigned int cpu; |
| |
| spin_lock(&workqueue_lock); |
| |
| if (!workqueue_freezing) |
| goto out_unlock; |
| |
| for_each_possible_cpu(cpu) { |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); |
| gcwq->flags &= ~GCWQ_FREEZING; |
| |
| list_for_each_entry(wq, &workqueues, list) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| |
| if (!(wq->flags & WQ_FREEZEABLE)) |
| continue; |
| |
| /* restore max_active and repopulate worklist */ |
| cwq->max_active = wq->saved_max_active; |
| |
| while (!list_empty(&cwq->delayed_works) && |
| cwq->nr_active < cwq->max_active) |
| cwq_activate_first_delayed(cwq); |
| |
| wake_up_process(cwq->worker->task); |
| } |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| workqueue_freezing = false; |
| out_unlock: |
| spin_unlock(&workqueue_lock); |
| } |
| #endif /* CONFIG_FREEZER */ |
| |
| void __init init_workqueues(void) |
| { |
| unsigned int cpu; |
| int i; |
| |
| singlethread_cpu = cpumask_first(cpu_possible_mask); |
| hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); |
| |
| /* initialize gcwqs */ |
| for_each_possible_cpu(cpu) { |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| |
| spin_lock_init(&gcwq->lock); |
| gcwq->cpu = cpu; |
| |
| INIT_LIST_HEAD(&gcwq->idle_list); |
| for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) |
| INIT_HLIST_HEAD(&gcwq->busy_hash[i]); |
| |
| ida_init(&gcwq->worker_ida); |
| |
| gcwq->trustee_state = TRUSTEE_DONE; |
| init_waitqueue_head(&gcwq->trustee_wait); |
| } |
| |
| keventd_wq = create_workqueue("events"); |
| BUG_ON(!keventd_wq); |
| } |