![Tejun Heo](/assets/img/avatar_default.png)
Implement worker states. After created, a worker is STARTED. While a worker isn't processing a work, it's IDLE and chained on gcwq->idle_list. While processing a work, a worker is BUSY and chained on gcwq->busy_hash. Also, gcwq now counts the number of all workers and idle ones. worker_thread() is restructured to reflect state transitions. cwq->more_work is removed and waking up a worker makes it check for events. A worker is killed by setting DIE flag while it's IDLE and waking it up. This gives gcwq better visibility of what's going on and allows it to find out whether a work is executing quickly which is necessary to have multiple workers processing the same cwq. Signed-off-by: Tejun Heo <tj@kernel.org>
2048 lines
52 KiB
C
2048 lines
52 KiB
C
/*
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* linux/kernel/workqueue.c
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*
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* Generic mechanism for defining kernel helper threads for running
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* arbitrary tasks in process context.
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*
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* Started by Ingo Molnar, Copyright (C) 2002
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*
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* Derived from the taskqueue/keventd code by:
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*
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* David Woodhouse <dwmw2@infradead.org>
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* Andrew Morton
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* Kai Petzke <wpp@marie.physik.tu-berlin.de>
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* Theodore Ts'o <tytso@mit.edu>
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*
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* Made to use alloc_percpu by Christoph Lameter.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/signal.h>
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#include <linux/completion.h>
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#include <linux/workqueue.h>
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#include <linux/slab.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/kthread.h>
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#include <linux/hardirq.h>
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#include <linux/mempolicy.h>
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#include <linux/freezer.h>
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#include <linux/kallsyms.h>
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#include <linux/debug_locks.h>
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#include <linux/lockdep.h>
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#include <linux/idr.h>
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enum {
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/* worker flags */
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WORKER_STARTED = 1 << 0, /* started */
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WORKER_DIE = 1 << 1, /* die die die */
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WORKER_IDLE = 1 << 2, /* is idle */
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BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
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BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER,
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BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1,
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};
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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: gcwq->lock protected. Access with gcwq->lock held.
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*
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* F: wq->flush_mutex protected.
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*
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* W: workqueue_lock protected.
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*/
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struct global_cwq;
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struct cpu_workqueue_struct;
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struct worker {
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/* on idle list while idle, on busy hash table while busy */
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union {
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struct list_head entry; /* L: while idle */
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struct hlist_node hentry; /* L: while busy */
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};
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struct work_struct *current_work; /* L: work being processed */
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struct list_head scheduled; /* L: scheduled works */
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struct task_struct *task; /* I: worker task */
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struct global_cwq *gcwq; /* I: the associated gcwq */
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struct cpu_workqueue_struct *cwq; /* I: the associated cwq */
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unsigned int flags; /* L: flags */
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int id; /* I: worker id */
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};
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/*
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* Global per-cpu workqueue.
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*/
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struct global_cwq {
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spinlock_t lock; /* the gcwq lock */
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unsigned int cpu; /* I: the associated cpu */
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int nr_workers; /* L: total number of workers */
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int nr_idle; /* L: currently idle ones */
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/* workers are chained either in the idle_list or busy_hash */
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struct list_head idle_list; /* L: list of idle workers */
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struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE];
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/* L: hash of busy workers */
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struct ida worker_ida; /* L: for worker IDs */
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} ____cacheline_aligned_in_smp;
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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). The lower WORK_STRUCT_FLAG_BITS of
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* work_struct->data are used for flags and thus cwqs need to be
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* aligned at two's power of the number of flag bits.
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*/
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struct cpu_workqueue_struct {
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struct global_cwq *gcwq; /* I: the associated gcwq */
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struct list_head worklist;
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struct worker *worker;
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struct workqueue_struct *wq; /* I: the owning workqueue */
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int work_color; /* L: current color */
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int flush_color; /* L: flushing color */
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int nr_in_flight[WORK_NR_COLORS];
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/* L: nr of in_flight works */
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int nr_active; /* L: nr of active works */
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int max_active; /* L: max active works */
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struct list_head delayed_works; /* L: delayed works */
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};
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/*
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* Structure used to wait for workqueue flush.
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*/
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struct wq_flusher {
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struct list_head list; /* F: list of flushers */
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int flush_color; /* F: flush color waiting for */
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struct completion done; /* flush completion */
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};
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/*
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* The externally visible workqueue abstraction is an array of
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* per-CPU workqueues:
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*/
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struct workqueue_struct {
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unsigned int flags; /* I: WQ_* flags */
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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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struct mutex flush_mutex; /* protects wq flushing */
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int work_color; /* F: current work color */
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int flush_color; /* F: current flush color */
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atomic_t nr_cwqs_to_flush; /* flush in progress */
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struct wq_flusher *first_flusher; /* F: first flusher */
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struct list_head flusher_queue; /* F: flush waiters */
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struct list_head flusher_overflow; /* F: flush overflow list */
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int saved_max_active; /* I: saved cwq max_active */
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const char *name; /* I: workqueue name */
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#ifdef CONFIG_LOCKDEP
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struct lockdep_map lockdep_map;
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#endif
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};
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#ifdef CONFIG_DEBUG_OBJECTS_WORK
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static struct debug_obj_descr work_debug_descr;
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/*
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* fixup_init is called when:
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* - an active object is initialized
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*/
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static int work_fixup_init(void *addr, enum debug_obj_state state)
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{
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struct work_struct *work = addr;
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switch (state) {
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case ODEBUG_STATE_ACTIVE:
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cancel_work_sync(work);
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debug_object_init(work, &work_debug_descr);
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return 1;
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default:
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return 0;
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}
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}
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/*
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* fixup_activate is called when:
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* - an active object is activated
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* - an unknown object is activated (might be a statically initialized object)
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*/
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static int work_fixup_activate(void *addr, enum debug_obj_state state)
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{
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struct work_struct *work = addr;
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switch (state) {
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case ODEBUG_STATE_NOTAVAILABLE:
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/*
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* This is not really a fixup. The work struct was
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* statically initialized. We just make sure that it
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* is tracked in the object tracker.
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*/
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if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
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debug_object_init(work, &work_debug_descr);
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debug_object_activate(work, &work_debug_descr);
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return 0;
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}
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WARN_ON_ONCE(1);
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return 0;
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case ODEBUG_STATE_ACTIVE:
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WARN_ON(1);
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default:
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return 0;
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}
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}
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/*
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* fixup_free is called when:
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* - an active object is freed
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*/
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static int work_fixup_free(void *addr, enum debug_obj_state state)
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{
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struct work_struct *work = addr;
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switch (state) {
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case ODEBUG_STATE_ACTIVE:
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cancel_work_sync(work);
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debug_object_free(work, &work_debug_descr);
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return 1;
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default:
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return 0;
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}
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}
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static struct debug_obj_descr work_debug_descr = {
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.name = "work_struct",
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.fixup_init = work_fixup_init,
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.fixup_activate = work_fixup_activate,
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.fixup_free = work_fixup_free,
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};
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static inline void debug_work_activate(struct work_struct *work)
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{
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debug_object_activate(work, &work_debug_descr);
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}
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static inline void debug_work_deactivate(struct work_struct *work)
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{
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debug_object_deactivate(work, &work_debug_descr);
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}
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void __init_work(struct work_struct *work, int onstack)
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{
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if (onstack)
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debug_object_init_on_stack(work, &work_debug_descr);
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else
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debug_object_init(work, &work_debug_descr);
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}
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EXPORT_SYMBOL_GPL(__init_work);
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void destroy_work_on_stack(struct work_struct *work)
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{
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debug_object_free(work, &work_debug_descr);
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}
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EXPORT_SYMBOL_GPL(destroy_work_on_stack);
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#else
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static inline void debug_work_activate(struct work_struct *work) { }
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static inline void debug_work_deactivate(struct work_struct *work) { }
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#endif
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/* Serializes the accesses to the list of workqueues. */
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static DEFINE_SPINLOCK(workqueue_lock);
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static LIST_HEAD(workqueues);
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static bool workqueue_freezing; /* W: have wqs started freezing? */
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static DEFINE_PER_CPU(struct global_cwq, global_cwq);
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static int worker_thread(void *__worker);
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static int singlethread_cpu __read_mostly;
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static struct global_cwq *get_gcwq(unsigned int cpu)
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{
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return &per_cpu(global_cwq, cpu);
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}
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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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return per_cpu_ptr(wq->cpu_wq, cpu);
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}
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static struct cpu_workqueue_struct *target_cwq(unsigned int cpu,
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struct workqueue_struct *wq)
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{
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if (unlikely(wq->flags & WQ_SINGLE_THREAD))
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cpu = singlethread_cpu;
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return get_cwq(cpu, wq);
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}
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static unsigned int work_color_to_flags(int color)
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{
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return color << WORK_STRUCT_COLOR_SHIFT;
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}
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static int get_work_color(struct work_struct *work)
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{
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return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
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((1 << WORK_STRUCT_COLOR_BITS) - 1);
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}
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static int work_next_color(int color)
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{
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return (color + 1) % WORK_NR_COLORS;
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}
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/*
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* Set the workqueue on which a work item is to be run
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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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unsigned long extra_flags)
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{
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BUG_ON(!work_pending(work));
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atomic_long_set(&work->data, (unsigned long)cwq | work_static(work) |
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WORK_STRUCT_PENDING | extra_flags);
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}
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/*
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* Clear WORK_STRUCT_PENDING and the workqueue on which it was queued.
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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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atomic_long_set(&work->data, work_static(work));
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}
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static inline struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)
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{
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return (void *)(atomic_long_read(&work->data) &
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WORK_STRUCT_WQ_DATA_MASK);
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}
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/**
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* busy_worker_head - return the busy hash head for a work
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* @gcwq: gcwq of interest
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* @work: work to be hashed
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*
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* Return hash head of @gcwq for @work.
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*
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* CONTEXT:
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* spin_lock_irq(gcwq->lock).
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*
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* RETURNS:
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* Pointer to the hash head.
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*/
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static struct hlist_head *busy_worker_head(struct global_cwq *gcwq,
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struct work_struct *work)
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{
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const int base_shift = ilog2(sizeof(struct work_struct));
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unsigned long v = (unsigned long)work;
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/* simple shift and fold hash, do we need something better? */
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v >>= base_shift;
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v += v >> BUSY_WORKER_HASH_ORDER;
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v &= BUSY_WORKER_HASH_MASK;
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return &gcwq->busy_hash[v];
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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(gcwq->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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unsigned int extra_flags)
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{
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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_process(cwq->worker->task);
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}
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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 = target_cwq(cpu, wq);
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struct global_cwq *gcwq = cwq->gcwq;
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struct list_head *worklist;
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unsigned long flags;
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debug_work_activate(work);
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spin_lock_irqsave(&gcwq->lock, flags);
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BUG_ON(!list_empty(&work->entry));
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cwq->nr_in_flight[cwq->work_color]++;
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if (likely(cwq->nr_active < cwq->max_active)) {
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cwq->nr_active++;
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worklist = &cwq->worklist;
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} else
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worklist = &cwq->delayed_works;
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insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color));
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spin_unlock_irqrestore(&gcwq->lock, flags);
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}
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/**
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* queue_work - queue work on a workqueue
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* @wq: workqueue to use
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* @work: work to queue
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*
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* Returns 0 if @work was already on a queue, non-zero otherwise.
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*
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* We queue the work to the CPU on which it was submitted, but if the CPU dies
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* it can be processed by another CPU.
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*/
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int queue_work(struct workqueue_struct *wq, struct work_struct *work)
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{
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int ret;
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ret = queue_work_on(get_cpu(), wq, work);
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put_cpu();
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return ret;
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}
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EXPORT_SYMBOL_GPL(queue_work);
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/**
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* queue_work_on - queue work on specific cpu
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* @cpu: CPU number to execute work on
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* @wq: workqueue to use
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* @work: work to queue
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*
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* Returns 0 if @work was already on a queue, non-zero otherwise.
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*
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* We queue the work to a specific CPU, the caller must ensure it
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* can't go away.
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*/
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int
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queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
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{
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int ret = 0;
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if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(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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}
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EXPORT_SYMBOL_GPL(queue_work_on);
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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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__queue_work(smp_processor_id(), cwq->wq, &dwork->work);
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}
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/**
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* queue_delayed_work - queue work on a workqueue after delay
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* @wq: workqueue to use
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* @dwork: delayable work to queue
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* @delay: number of jiffies to wait before queueing
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*
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* Returns 0 if @work was already on a queue, non-zero otherwise.
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*/
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int queue_delayed_work(struct workqueue_struct *wq,
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struct delayed_work *dwork, unsigned long delay)
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{
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if (delay == 0)
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return queue_work(wq, &dwork->work);
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return queue_delayed_work_on(-1, wq, dwork, delay);
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}
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EXPORT_SYMBOL_GPL(queue_delayed_work);
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/**
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* queue_delayed_work_on - queue work on specific CPU after delay
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* @cpu: CPU number to execute work on
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* @wq: workqueue to use
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* @dwork: work to queue
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* @delay: number of jiffies to wait before queueing
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*
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* Returns 0 if @work was already on a queue, non-zero otherwise.
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*/
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int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
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struct delayed_work *dwork, unsigned long delay)
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{
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int ret = 0;
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struct timer_list *timer = &dwork->timer;
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struct work_struct *work = &dwork->work;
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if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
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BUG_ON(timer_pending(timer));
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BUG_ON(!list_empty(&work->entry));
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|
|
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);
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
|
|
if (bind)
|
|
kthread_bind(worker->task, gcwq->cpu);
|
|
|
|
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:
|
|
if (unlikely(!cpumask_equal(&worker->task->cpus_allowed,
|
|
get_cpu_mask(gcwq->cpu))))
|
|
set_cpus_allowed_ptr(worker->task, get_cpu_mask(gcwq->cpu));
|
|
|
|
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);
|
|
|
|
/*
|
|
* ->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);
|
|
|
|
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);
|
|
|
|
static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
|
|
unsigned long action,
|
|
void *hcpu)
|
|
{
|
|
unsigned int cpu = (unsigned long)hcpu;
|
|
struct cpu_workqueue_struct *cwq;
|
|
struct workqueue_struct *wq;
|
|
|
|
action &= ~CPU_TASKS_FROZEN;
|
|
|
|
list_for_each_entry(wq, &workqueues, list) {
|
|
if (wq->flags & WQ_SINGLE_THREAD)
|
|
continue;
|
|
|
|
cwq = get_cwq(cpu, wq);
|
|
|
|
switch (action) {
|
|
case CPU_POST_DEAD:
|
|
flush_workqueue(wq);
|
|
break;
|
|
}
|
|
}
|
|
|
|
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);
|
|
|
|
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);
|
|
|
|
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, 0);
|
|
|
|
/* 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);
|
|
}
|
|
|
|
keventd_wq = create_workqueue("events");
|
|
BUG_ON(!keventd_wq);
|
|
}
|