litmus-rt.git - The LITMUS^RT kernel.

diff options

author	manjugk manjugk <manjugk@ti.com>	2010-02-19 07:09:16 -0500
committer	Tony Lindgren <tony@atomide.com>	2010-02-25 17:45:08 -0500
commit	93bfc85b2361dec0d2b8b93311ce482957e34f5b (patch)
tree	64a41566012124ad3db1313c9d40409f1a8927c1 /lib/spinlock_debug.c
parent	9833eff3d7db76d2d04f28567ed8704d69e225ae (diff)

Zoom3: Defconfig update

Some of the features are not enabled by default in zoom3 defconfig. This patch enables: - MMC Resume - TWL4030 RTC driver - Debug File system Build and boot tested on Zoom3 board. Signed-off-by: Manjunatha GK <manjugk@ti.com> Signed-off-by: Tony Lindgren <tony@atomide.com>

Diffstat (limited to 'lib/spinlock_debug.c')

0 files changed, 0 insertions, 0 deletions

/* * kernel/workqueue.c - generic async execution with shared worker pool * * Copyright (C) 2002 Ingo Molnar * * 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. * * Copyright (C) 2010 SUSE Linux Products GmbH * Copyright (C) 2010 Tejun Heo <tj@kernel.org> * * This is the generic async execution mechanism. Work items as are * executed in process context. The worker pool is shared and * automatically managed. There is one worker pool for each CPU and * one extra for works which are better served by workers which are * not bound to any specific CPU. * * Please read Documentation/workqueue.txt for details. */ #include <linux/export.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> #include <linux/jhash.h> #include <linux/hashtable.h> #include <linux/rculist.h> #include "workqueue_internal.h" enum { /* * worker_pool flags * * A bound pool is either associated or disassociated with its CPU. * While associated (!DISASSOCIATED), all workers are bound to the * CPU and none has %WORKER_UNBOUND set and concurrency management * is in effect. * * While DISASSOCIATED, the cpu may be offline and all workers have * %WORKER_UNBOUND set and concurrency management disabled, and may * be executing on any CPU. The pool behaves as an unbound one. * * Note that DISASSOCIATED should be flipped only while holding * manager_mutex to avoid changing binding state while * create_worker() is in progress. */ POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ POOL_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_PREP = 1 << 3, /* preparing to run works */ WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ WORKER_UNBOUND = 1 << 7, /* worker is unbound */ WORKER_REBOUND = 1 << 8, /* worker was rebound */ WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | WORKER_UNBOUND | WORKER_REBOUND, NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, /* call for help after 10ms (min two ticks) */ MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ CREATE_COOLDOWN = HZ, /* time to breath after fail */ /* * Rescue workers are used only on emergencies and shared by * all cpus. Give -20. */ RESCUER_NICE_LEVEL = -20, HIGHPRI_NICE_LEVEL = -20, }; /* * Structure fields follow one of the following exclusion rules. * * I: Modifiable by initialization/destruction paths and read-only for * everyone else. * * P: Preemption protected. Disabling preemption is enough and should * only be modified and accessed from the local cpu. * * L: pool->lock protected. Access with pool->lock held. * * X: During normal operation, modification requires pool->lock and should * be done only from local cpu. Either disabling preemption on local * cpu or grabbing pool->lock is enough for read access. If * POOL_DISASSOCIATED is set, it's identical to L. * * MG: pool->manager_mutex and pool->lock protected. Writes require both * locks. Reads can happen under either lock. * * PL: wq_pool_mutex protected. * * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads. * * PW: pwq_lock protected. * * WQ: wq->mutex protected. * * WR: wq->mutex and pwq_lock protected for writes. Sched-RCU protected * for reads. * * MD: wq_mayday_lock protected. */ /* struct worker is defined in workqueue_internal.h */ struct worker_pool { spinlock_t lock; /* the pool lock */ int cpu; /* I: the associated cpu */ int id; /* I: pool ID */ unsigned int flags; /* X: flags */ struct list_head worklist; /* L: list of pending works */ int nr_workers; /* L: total number of workers */ /* nr_idle includes the ones off idle_list for rebinding */ int nr_idle; /* L: currently idle ones */ struct list_head idle_list; /* X: list of idle workers */ struct timer_list idle_timer; /* L: worker idle timeout */ struct timer_list mayday_timer; /* L: SOS timer for workers */ /* a workers is either on busy_hash or idle_list, or the manager */ DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); /* L: hash of busy workers */ /* see manage_workers() for details on the two manager mutexes */ struct mutex manager_arb; /* manager arbitration */ struct mutex manager_mutex; /* manager exclusion */ struct idr worker_idr; /* MG: worker IDs and iteration */ struct workqueue_attrs *attrs; /* I: worker attributes */ struct hlist_node hash_node; /* PL: unbound_pool_hash node */ int refcnt; /* PL: refcnt for unbound pools */ /* * The current concurrency level. As it's likely to be accessed * from other CPUs during try_to_wake_up(), put it in a separate * cacheline. */ atomic_t nr_running ____cacheline_aligned_in_smp; /* * Destruction of pool is sched-RCU protected to allow dereferences * from get_work_pool(). */ struct rcu_head rcu; } ____cacheline_aligned_in_smp; /* * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS * of work_struct->data are used for flags and the remaining high bits * point to the pwq; thus, pwqs need to be aligned at two's power of the * number of flag bits. */ struct pool_workqueue { struct worker_pool *pool; /* I: the associated pool */ struct workqueue_struct *wq; /* I: the owning workqueue */ int work_color; /* L: current color */ int flush_color; /* L: flushing color */ int refcnt; /* L: reference count */ 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 */ struct list_head pwqs_node; /* WR: node on wq->pwqs */ struct list_head mayday_node; /* MD: node on wq->maydays */ /* * Release of unbound pwq is punted to system_wq. See put_pwq() * and pwq_unbound_release_workfn() for details. pool_workqueue * itself is also sched-RCU protected so that the first pwq can be * determined without grabbing wq->mutex. */ struct work_struct unbound_release_work; struct rcu_head rcu; } __aligned(1 << WORK_STRUCT_FLAG_BITS); /* * Structure used to wait for workqueue flush. */ struct wq_flusher { struct list_head list; /* WQ: list of flushers */ int flush_color; /* WQ: flush color waiting for */ struct completion done; /* flush completion */ }; struct wq_device; /* * The externally visible workqueue. It relays the issued work items to * the appropriate worker_pool through its pool_workqueues. */ struct workqueue_struct { unsigned int flags; /* WQ: WQ_* flags */ struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwq's */ struct list_head pwqs; /* WR: all pwqs of this wq */ struct list_head list; /* PL: list of all workqueues */ struct mutex mutex; /* protects this wq */ int work_color; /* WQ: current work color */ int flush_color; /* WQ: current flush color */ atomic_t nr_pwqs_to_flush; /* flush in progress */ struct wq_flusher *first_flusher; /* WQ: first flusher */ struct list_head flusher_queue; /* WQ: flush waiters */ struct list_head flusher_overflow; /* WQ: flush overflow list */ struct list_head maydays; /* MD: pwqs requesting rescue */ struct worker *rescuer; /* I: rescue worker */ int nr_drainers; /* WQ: drain in progress */ int saved_max_active; /* PW: saved pwq max_active */ #ifdef CONFIG_SYSFS struct wq_device *wq_dev; /* I: for sysfs interface */ #endif #ifdef CONFIG_LOCKDEP struct lockdep_map lockdep_map; #endif char name[]; /* I: workqueue name */ }; static struct kmem_cache *pwq_cache; static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ static DEFINE_SPINLOCK(pwq_lock); /* protects pool_workqueues */ static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ static LIST_HEAD(workqueues); /* PL: list of all workqueues */ static bool workqueue_freezing; /* PL: have wqs started freezing? */ /* the per-cpu worker pools */ static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools); static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ /* PL: hash of all unbound pools keyed by pool->attrs */ static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); /* I: attributes used when instantiating standard unbound pools on demand */ static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; struct workqueue_struct *system_wq __read_mostly; EXPORT_SYMBOL_GPL(system_wq); struct workqueue_struct *system_highpri_wq __read_mostly; EXPORT_SYMBOL_GPL(system_highpri_wq); struct workqueue_struct *system_long_wq __read_mostly; EXPORT_SYMBOL_GPL(system_long_wq); struct workqueue_struct *system_unbound_wq __read_mostly; EXPORT_SYMBOL_GPL(system_unbound_wq); struct workqueue_struct *system_freezable_wq __read_mostly; EXPORT_SYMBOL_GPL(system_freezable_wq); static int worker_thread(void *__worker); static void copy_workqueue_attrs(struct workqueue_attrs *to, const struct workqueue_attrs *from); #define CREATE_TRACE_POINTS #include <trace/events/workqueue.h> #define assert_rcu_or_pool_mutex() \ rcu_lockdep_assert(rcu_read_lock_sched_held() || \ lockdep_is_held(&wq_pool_mutex), \ "sched RCU or wq_pool_mutex should be held") #define assert_rcu_or_wq_mutex(wq) \ rcu_lockdep_assert(rcu_read_lock_sched_held() || \ lockdep_is_held(&wq->mutex) || \ lockdep_is_held(&pwq_lock), \ "sched RCU or wq->mutex should be held") #ifdef CONFIG_LOCKDEP #define assert_manager_or_pool_lock(pool) \ WARN_ONCE(debug_locks && \ !lockdep_is_held(&(pool)->manager_mutex) && \ !lockdep_is_held(&(pool)->lock), \ "pool->manager_mutex or ->lock should be held") #else #define assert_manager_or_pool_lock(pool) do { } while (0) #endif #define for_each_cpu_worker_pool(pool, cpu) \ for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ (pool)++) /** * for_each_pool - iterate through all worker_pools in the system * @pool: iteration cursor * @pi: integer used for iteration * * This must be called either with wq_pool_mutex held or sched RCU read * locked. If the pool needs to be used beyond the locking in effect, the * caller is responsible for guaranteeing that the pool stays online. * * The if/else clause exists only for the lockdep assertion and can be * ignored. */ #define for_each_pool(pool, pi) \ idr_for_each_entry(&worker_pool_idr, pool, pi) \ if (({ assert_rcu_or_pool_mutex(); false; })) { } \ else /** * for_each_pool_worker - iterate through all workers of a worker_pool * @worker: iteration cursor * @wi: integer used for iteration * @pool: worker_pool to iterate workers of * * This must be called with either @pool->manager_mutex or ->lock held. * * The if/else clause exists only for the lockdep assertion and can be * ignored. */ #define for_each_pool_worker(worker, wi, pool) \ idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \ if (({ assert_manager_or_pool_lock((pool)); false; })) { } \ else /** * for_each_pwq - iterate through all pool_workqueues of the specified workqueue * @pwq: iteration cursor * @wq: the target workqueue * * This must be called either with wq->mutex held or sched RCU read locked. * If the pwq needs to be used beyond the locking in effect, the caller is * responsible for guaranteeing that the pwq stays online. * * The if/else clause exists only for the lockdep assertion and can be * ignored. */ #define for_each_pwq(pwq, wq) \ list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \ if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \ else #ifdef CONFIG_DEBUG_OBJECTS_WORK static struct debug_obj_descr work_debug_descr; static void *work_debug_hint(void *addr) { return ((struct work_struct *) addr)->func; } /* * 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", .debug_hint = work_debug_hint, .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 /* allocate ID and assign it to @pool */ static int worker_pool_assign_id(struct worker_pool *pool) { int ret; lockdep_assert_held(&wq_pool_mutex); do { if (!idr_pre_get(&worker_pool_idr, GFP_KERNEL)) return -ENOMEM; ret = idr_get_new(&worker_pool_idr, pool, &pool->id); } while (ret == -EAGAIN); return ret; } /** * first_pwq - return the first pool_workqueue of the specified workqueue * @wq: the target workqueue * * This must be called either with wq->mutex held or sched RCU read locked. * If the pwq needs to be used beyond the locking in effect, the caller is * responsible for guaranteeing that the pwq stays online. */ static struct pool_workqueue *first_pwq(struct workqueue_struct *wq) { assert_rcu_or_wq_mutex(wq); return list_first_or_null_rcu(&wq->pwqs, struct pool_workqueue, pwqs_node); } 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; } /* * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data * contain the pointer to the queued pwq. Once execution starts, the flag * is cleared and the high bits contain OFFQ flags and pool ID. * * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() * and clear_work_data() can be used to set the pwq, pool or clear * work->data. These functions should only be called while the work is * owned - ie. while the PENDING bit is set. * * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq * corresponding to a work. Pool is available once the work has been * queued anywhere after initialization until it is sync canceled. pwq is * available only while the work item is queued. * * %WORK_OFFQ_CANCELING is used to mark a work item which is being * canceled. While being canceled, a work item may have its PENDING set * but stay off timer and worklist for arbitrarily long and nobody should * try to steal the PENDING bit. */ static inline void set_work_data(struct work_struct *work, unsigned long data, unsigned long flags) { WARN_ON_ONCE(!work_pending(work)); atomic_long_set(&work->data, data | flags | work_static(work)); } static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, unsigned long extra_flags) { set_work_data(work, (unsigned long)pwq, WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); } static void set_work_pool_and_keep_pending(struct work_struct *work, int pool_id) { set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, WORK_STRUCT_PENDING); } static void set_work_pool_and_clear_pending(struct work_struct *work, int pool_id) { /* * The following wmb is paired with the implied mb in * test_and_set_bit(PENDING) and ensures all updates to @work made * here are visible to and precede any updates by the next PENDING * owner. */ smp_wmb(); set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); } static void clear_work_data(struct work_struct *work) { smp_wmb(); /* see set_work_pool_and_clear_pending() */ set_work_data(work, WORK_STRUCT_NO_POOL, 0); } static struct pool_workqueue *get_work_pwq(struct work_struct *work) { unsigned long data = atomic_long_read(&work->data); if (data & WORK_STRUCT_PWQ) return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); else return NULL; } /** * get_work_pool - return the worker_pool a given work was associated with * @work: the work item of interest * * Return the worker_pool @work was last associated with. %NULL if none. * * Pools are created and destroyed under wq_pool_mutex, and allows read * access under sched-RCU read lock. As such, this function should be * called under wq_pool_mutex or with preemption disabled. * * All fields of the returned pool are accessible as long as the above * mentioned locking is in effect. If the returned pool needs to be used * beyond the critical section, the caller is responsible for ensuring the * returned pool is and stays online. */ static struct worker_pool *get_work_pool(struct work_struct *work) { unsigned long data = atomic_long_read(&work->data); int pool_id; assert_rcu_or_pool_mutex(); if (data & WORK_STRUCT_PWQ) return ((struct pool_workqueue *) (data & WORK_STRUCT_WQ_DATA_MASK))->pool; pool_id = data >> WORK_OFFQ_POOL_SHIFT; if (pool_id == WORK_OFFQ_POOL_NONE) return NULL; return idr_find(&worker_pool_idr, pool_id); } /** * get_work_pool_id - return the worker pool ID a given work is associated with * @work: the work item of interest * * Return the worker_pool ID @work was last associated with. * %WORK_OFFQ_POOL_NONE if none. */ static int get_work_pool_id(struct work_struct *work) { unsigned long data = atomic_long_read(&work->data); if (data & WORK_STRUCT_PWQ) return ((struct pool_workqueue *) (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; return data >> WORK_OFFQ_POOL_SHIFT; } static void mark_work_canceling(struct work_struct *work) { unsigned long pool_id = get_work_pool_id(work); pool_id <<= WORK_OFFQ_POOL_SHIFT; set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); } static bool work_is_canceling(struct work_struct *work) { unsigned long data = atomic_long_read(&work->data); return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); } /* * Policy functions. These define the policies on how the global worker * pools are managed. Unless noted otherwise, these functions assume that * they're being called with pool->lock held. */ static bool __need_more_worker(struct worker_pool *pool) { return !atomic_read(&pool->nr_running); } /* * Need to wake up a worker? Called from anything but currently * running workers. * * Note that, because unbound workers never contribute to nr_running, this * function will always return %true for unbound pools as long as the * worklist isn't empty. */ static bool need_more_worker(struct worker_pool *pool) { return !list_empty(&pool->worklist) && __need_more_worker(pool); } /* Can I start working? Called from busy but !running workers. */ static bool may_start_working(struct worker_pool *pool) { return pool->nr_idle; } /* Do I need to keep working? Called from currently running workers. */ static bool keep_working(struct worker_pool *pool) { return !list_empty(&pool->worklist) && atomic_read(&pool->nr_running) <= 1; } /* Do we need a new worker? Called from manager. */ static bool need_to_create_worker(struct worker_pool *pool) { return need_more_worker(pool) && !may_start_working(pool); } /* Do I need to be the manager? */ static bool need_to_manage_workers(struct worker_pool *pool) { return need_to_create_worker(pool) || (pool->flags & POOL_MANAGE_WORKERS); } /* Do we have too many workers and should some go away? */ static bool too_many_workers(struct worker_pool *pool) { bool managing = mutex_is_locked(&pool->manager_arb); int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ int nr_busy = pool->nr_workers - nr_idle; /* * nr_idle and idle_list may disagree if idle rebinding is in * progress. Never return %true if idle_list is empty. */ if (list_empty(&pool->idle_list)) return false; return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; } /* * Wake up functions. */ /* Return the first worker. Safe with preemption disabled */ static struct worker *first_worker(struct worker_pool *pool) { if (unlikely(list_empty(&pool->idle_list))) return NULL; return list_first_entry(&pool->idle_list, struct worker, entry); } /** * wake_up_worker - wake up an idle worker * @pool: worker pool to wake worker from * * Wake up the first idle worker of @pool. * * CONTEXT: * spin_lock_irq(pool->lock). */ static void wake_up_worker(struct worker_pool *pool) { struct worker *worker = first_worker(pool); if (likely(worker)) wake_up_process(worker->task); } /** * wq_worker_waking_up - a worker is waking up * @task: task waking up * @cpu: CPU @task is waking up to * * This function is called during try_to_wake_up() when a worker is * being awoken. * * CONTEXT: * spin_lock_irq(rq->lock) */ void wq_worker_waking_up(struct task_struct *task, int cpu) { struct worker *worker = kthread_data(task); if (!(worker->flags & WORKER_NOT_RUNNING)) { WARN_ON_ONCE(worker->pool->cpu != cpu); atomic_inc(&worker->pool->nr_running); } } /** * wq_worker_sleeping - a worker is going to sleep * @task: task going to sleep * @cpu: CPU in question, must be the current CPU number * * This function is called during schedule() when a busy worker is * going to sleep. Worker on the same cpu can be woken up by * returning pointer to its task. * * CONTEXT: * spin_lock_irq(rq->lock) * * RETURNS: * Worker task on @cpu to wake up, %NULL if none. */ struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu) { struct worker *worker = kthread_data(task), *to_wakeup = NULL; struct worker_pool *pool; /* * Rescuers, which may not have all the fields set up like normal * workers, also reach here, let's not access anything before * checking NOT_RUNNING. */ if (worker->flags & WORKER_NOT_RUNNING) return NULL; pool = worker->pool; /* this can only happen on the local cpu */ if (WARN_ON_ONCE(cpu != raw_smp_processor_id())) return NULL; /* * The counterpart of the following dec_and_test, implied mb, * worklist not empty test sequence is in insert_work(). * Please read comment there. * * NOT_RUNNING is clear. This means that we're bound to and * running on the local cpu w/ rq lock held and preemption * disabled, which in turn means that none else could be * manipulating idle_list, so dereferencing idle_list without pool * lock is safe. */ if (atomic_dec_and_test(&pool->nr_running) && !list_empty(&pool->worklist)) to_wakeup = first_worker(pool); return to_wakeup ? to_wakeup->task : NULL; } /** * worker_set_flags - set worker flags and adjust nr_running accordingly * @worker: self * @flags: flags to set * @wakeup: wakeup an idle worker if necessary * * Set @flags in @worker->flags and adjust nr_running accordingly. If * nr_running becomes zero and @wakeup is %true, an idle worker is * woken up. * * CONTEXT: * spin_lock_irq(pool->lock) */ static inline void worker_set_flags(struct worker *worker, unsigned int flags, bool wakeup) { struct worker_pool *pool = worker->pool; WARN_ON_ONCE(worker->task != current); /* * If transitioning into NOT_RUNNING, adjust nr_running and * wake up an idle worker as necessary if requested by * @wakeup. */ if ((flags & WORKER_NOT_RUNNING) && !(worker->flags & WORKER_NOT_RUNNING)) { if (wakeup) { if (atomic_dec_and_test(&pool->nr_running) && !list_empty(&pool->worklist)) wake_up_worker(pool); } else atomic_dec(&pool->nr_running); } worker->flags |= flags; } /** * worker_clr_flags - clear worker flags and adjust nr_running accordingly * @worker: self * @flags: flags to clear * * Clear @flags in @worker->flags and adjust nr_running accordingly. * * CONTEXT: * spin_lock_irq(pool->lock) */ static inline void worker_clr_flags(struct worker *worker, unsigned int flags) { struct worker_pool *pool = worker->pool; unsigned int oflags = worker->flags; WARN_ON_ONCE(worker->task != current); worker->flags &= ~flags; /* * If transitioning out of NOT_RUNNING, increment nr_running. Note * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask * of multiple flags, not a single flag. */ if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) if (!(worker->flags & WORKER_NOT_RUNNING)) atomic_inc(&pool->nr_running); } /** * find_worker_executing_work - find worker which is executing a work * @pool: pool of interest * @work: work to find worker for * * Find a worker which is executing @work on @pool by searching * @pool->busy_hash which is keyed by the address of @work. For a worker * to match, its current execution should match the address of @work and * its work function. This is to avoid unwanted dependency between * unrelated work executions through a work item being recycled while still * being executed. * * This is a bit tricky. A work item may be freed once its execution * starts and nothing prevents the freed area from being recycled for * another work item. If the same work item address ends up being reused * before the original execution finishes, workqueue will identify the * recycled work item as currently executing and make it wait until the * current execution finishes, introducing an unwanted dependency. * * This function checks the work item address and work function to avoid * false positives. Note that this isn't complete as one may construct a * work function which can introduce dependency onto itself through a * recycled work item. Well, if somebody wants to shoot oneself in the * foot that badly, there's only so much we can do, and if such deadlock * actually occurs, it should be easy to locate the culprit work function. * * CONTEXT: * spin_lock_irq(pool->lock). * * RETURNS: * Pointer to worker which is executing @work if found, NULL * otherwise. */ static struct worker *find_worker_executing_work(struct worker_pool *pool, struct work_struct *work) { struct worker *worker; hash_for_each_possible(pool->busy_hash, worker, hentry, (unsigned long)work) if (worker->current_work == work && worker->current_func == work->func) return worker; return NULL; } /** * 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(pool->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; } /** * get_pwq - get an extra reference on the specified pool_workqueue * @pwq: pool_workqueue to get * * Obtain an extra reference on @pwq. The caller should guarantee that * @pwq has positive refcnt and be holding the matching pool->lock. */ static void get_pwq(struct pool_workqueue *pwq) { lockdep_assert_held(&pwq->pool->lock); WARN_ON_ONCE(pwq->refcnt <= 0); pwq->refcnt++; } /** * put_pwq - put a pool_workqueue reference * @pwq: pool_workqueue to put * * Drop a reference of @pwq. If its refcnt reaches zero, schedule its * destruction. The caller should be holding the matching pool->lock. */ static void put_pwq(struct pool_workqueue *pwq) { lockdep_assert_held(&pwq->pool->lock); if (likely(--pwq->refcnt)) return; if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) return; /* * @pwq can't be released under pool->lock, bounce to * pwq_unbound_release_workfn(). This never recurses on the same * pool->lock as this path is taken only for unbound workqueues and * the release work item is scheduled on a per-cpu workqueue. To * avoid lockdep warning, unbound pool->locks are given lockdep * subclass of 1 in get_unbound_pool(). */ schedule_work(&pwq->unbound_release_work); } static void pwq_activate_delayed_work(struct work_struct *work) { struct pool_workqueue *pwq = get_work_pwq(work); trace_workqueue_activate_work(work); move_linked_works(work, &pwq->pool->worklist, NULL); __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); pwq->nr_active++; } static void pwq_activate_first_delayed(struct pool_workqueue *pwq) { struct work_struct *work = list_first_entry(&pwq->delayed_works, struct work_struct, entry); pwq_activate_delayed_work(work); } /** * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight * @pwq: pwq 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 pwq and handle workqueue flushing. * * CONTEXT: * spin_lock_irq(pool->lock). */ static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) { /* uncolored work items don't participate in flushing or nr_active */ if (color == WORK_NO_COLOR) goto out_put; pwq->nr_in_flight[color]--; pwq->nr_active--; if (!list_empty(&pwq->delayed_works)) { /* one down, submit a delayed one */ if (pwq->nr_active < pwq->max_active) pwq_activate_first_delayed(pwq); } /* is flush in progress and are we at the flushing tip? */ if (likely(pwq->flush_color != color)) goto out_put; /* are there still in-flight works? */ if (pwq->nr_in_flight[color]) goto out_put; /* this pwq is done, clear flush_color */ pwq->flush_color = -1; /* * If this was the last pwq, wake up the first flusher. It * will handle the rest. */ if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) complete(&pwq->wq->first_flusher->done); out_put: put_pwq(pwq); } /** * try_to_grab_pending - steal work item from worklist and disable irq * @work: work item to steal * @is_dwork: @work is a delayed_work * @flags: place to store irq state * * Try to grab PENDING bit of @work. This function can handle @work in any * stable state - idle, on timer or on worklist. Return values are * * 1 if @work was pending and we successfully stole PENDING * 0 if @work was idle and we claimed PENDING * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry * -ENOENT if someone else is canceling @work, this state may persist * for arbitrarily long * * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting * interrupted while holding PENDING and @work off queue, irq must be * disabled on entry. This, combined with delayed_work->timer being * irqsafe, ensures that we return -EAGAIN for finite short period of time. * * On successful return, >= 0, irq is disabled and the caller is * responsible for releasing it using local_irq_restore(*@flags). * * This function is safe to call from any context including IRQ handler. */ static int try_to_grab_pending(struct work_struct *work, bool is_dwork, unsigned long *flags) { struct worker_pool *pool; struct pool_workqueue *pwq; local_irq_save(*flags); /* try to steal the timer if it exists */ if (is_dwork) { struct delayed_work *dwork = to_delayed_work(work); /* * dwork->timer is irqsafe. If del_timer() fails, it's * guaranteed that the timer is not queued anywhere and not * running on the local CPU. */ if (likely(del_timer(&dwork->timer))) return 1; } /* try to claim PENDING the normal way */ 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. */ pool = get_work_pool(work); if (!pool) goto fail; spin_lock(&pool->lock); /* * work->data is guaranteed to point to pwq only while the work * item is queued on pwq->wq, and both updating work->data to point * to pwq on queueing and to pool on dequeueing are done under * pwq->pool->lock. This in turn guarantees that, if work->data * points to pwq which is associated with a locked pool, the work * item is currently queued on that pool. */ pwq = get_work_pwq(work); if (pwq && pwq->pool == pool) { debug_work_deactivate(work); /* * A delayed work item cannot be grabbed directly because * it might have linked NO_COLOR work items which, if left * on the delayed_list, will confuse pwq->nr_active * management later on and cause stall. Make sure the work * item is activated before grabbing. */ if (*work_data_bits(work) & WORK_STRUCT_DELAYED) pwq_activate_delayed_work(work); list_del_init(&work->entry); pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work)); /* work->data points to pwq iff queued, point to pool */ set_work_pool_and_keep_pending(work, pool->id); spin_unlock(&pool->lock); return 1; } spin_unlock(&pool->lock); fail: local_irq_restore(*flags); if (work_is_canceling(work)) return -ENOENT; cpu_relax(); return -EAGAIN; } /** * insert_work - insert a work into a pool * @pwq: pwq @work belongs to * @work: work to insert * @head: insertion point * @extra_flags: extra WORK_STRUCT_* flags to set * * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to * work_struct flags. * * CONTEXT: * spin_lock_irq(pool->lock). */ static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, struct list_head *head, unsigned int extra_flags) { struct worker_pool *pool = pwq->pool; /* we own @work, set data and link */ set_work_pwq(work, pwq, extra_flags); list_add_tail(&work->entry, head); get_pwq(pwq); /* * Ensure either wq_worker_sleeping() sees the above * list_add_tail() or we see zero nr_running to avoid workers lying * around lazily while there are works to be processed. */ smp_mb(); if (__need_more_worker(pool)) wake_up_worker(pool); } /* * Test whether @work is being queued from another work executing on the * same workqueue. */ static bool is_chained_work(struct workqueue_struct *wq) { struct worker *worker; worker = current_wq_worker(); /* * Return %true iff I'm a worker execuing a work item on @wq. If * I'm @worker, it's safe to dereference it without locking. */ return worker && worker->current_pwq->wq == wq; } static void __queue_work(int cpu, struct workqueue_struct *wq, struct work_struct *work) { struct pool_workqueue *pwq; struct worker_pool *last_pool; struct list_head *worklist; unsigned int work_flags; unsigned int req_cpu = cpu; /* * While a work item is PENDING && off queue, a task trying to * steal the PENDING will busy-loop waiting for it to either get * queued or lose PENDING. Grabbing PENDING and queueing should * happen with IRQ disabled. */ WARN_ON_ONCE(!irqs_disabled()); debug_work_activate(work); /* if dying, only works from the same workqueue are allowed */ if (unlikely(wq->flags & __WQ_DRAINING) && WARN_ON_ONCE(!is_chained_work(wq))) return; retry: /* pwq which will be used unless @work is executing elsewhere */ if (!(wq->flags & WQ_UNBOUND)) { if (cpu == WORK_CPU_UNBOUND) cpu = raw_smp_processor_id(); pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); } else { pwq = first_pwq(wq); } /* * If @work was previously on a different pool, it might still be * running there, in which case the work needs to be queued on that * pool to guarantee non-reentrancy. */ last_pool = get_work_pool(work); if (last_pool && last_pool != pwq->pool) { struct worker *worker; spin_lock(&last_pool->lock); worker = find_worker_executing_work(last_pool, work); if (worker && worker->current_pwq->wq == wq) { pwq = worker->current_pwq; } else { /* meh... not running there, queue here */ spin_unlock(&last_pool->lock); spin_lock(&pwq->pool->lock); } } else { spin_lock(&pwq->pool->lock); } /* * pwq is determined and locked. For unbound pools, we could have * raced with pwq release and it could already be dead. If its * refcnt is zero, repeat pwq selection. Note that pwqs never die * without another pwq replacing it as the first pwq or while a * work item is executing on it, so the retying is guaranteed to * make forward-progress. */ if (unlikely(!pwq->refcnt)) { if (wq->flags & WQ_UNBOUND) { spin_unlock(&pwq->pool->lock); cpu_relax(); goto retry; } /* oops */ WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", wq->name, cpu); } /* pwq determined, queue */ trace_workqueue_queue_work(req_cpu, pwq, work); if (WARN_ON(!list_empty(&work->entry))) { spin_unlock(&pwq->pool->lock); return; } pwq->nr_in_flight[pwq->work_color]++; work_flags = work_color_to_flags(pwq->work_color); if (likely(pwq->nr_active < pwq->max_active)) { trace_workqueue_activate_work(work); pwq->nr_active++; worklist = &pwq->pool->worklist; } else { work_flags |= WORK_STRUCT_DELAYED; worklist = &pwq->delayed_works; } insert_work(pwq, work, worklist, work_flags); spin_unlock(&pwq->pool->lock); } /** * queue_work_on - queue work on specific cpu * @cpu: CPU number to execute work on * @wq: workqueue to use * @work: work to queue * * Returns %false if @work was already on a queue, %true otherwise. * * We queue the work to a specific CPU, the caller must ensure it * can't go away. */ bool queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) { bool ret = false; unsigned long flags; local_irq_save(flags); if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { __queue_work(cpu, wq, work); ret = true; } local_irq_restore(flags); return ret; } EXPORT_SYMBOL_GPL(queue_work_on); void delayed_work_timer_fn(unsigned long __data) { struct delayed_work *dwork = (struct delayed_work *)__data; /* should have been called from irqsafe timer with irq already off */ __queue_work(dwork->cpu, dwork->wq, &dwork->work); } EXPORT_SYMBOL(delayed_work_timer_fn); static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, struct delayed_work *dwork, unsigned long delay) { struct timer_list *timer = &dwork->timer; struct work_struct *work = &dwork->work; WARN_ON_ONCE(timer->function != delayed_work_timer_fn || timer->data != (unsigned long)dwork); WARN_ON_ONCE(timer_pending(timer)); WARN_ON_ONCE(!list_empty(&work->entry)); /* * If @delay is 0, queue @dwork->work immediately. This is for * both optimization and correctness. The earliest @timer can * expire is on the closest next tick and delayed_work users depend * on that there's no such delay when @delay is 0. */ if (!delay) { __queue_work(cpu, wq, &dwork->work); return; } timer_stats_timer_set_start_info(&dwork->timer); dwork->wq = wq; dwork->cpu = cpu; timer->expires = jiffies + delay; if (unlikely(cpu != WORK_CPU_UNBOUND)) add_timer_on(timer, cpu); else add_timer(timer); } /** * 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 %false if @work was already on a queue, %true otherwise. If * @delay is zero and @dwork is idle, it will be scheduled for immediate * execution. */ bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, struct delayed_work *dwork, unsigned long delay) { struct work_struct *work = &dwork->work; bool ret = false; unsigned long flags; /* read the comment in __queue_work() */ local_irq_save(flags); if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { __queue_delayed_work(cpu, wq, dwork, delay); ret = true; } local_irq_restore(flags); return ret; } EXPORT_SYMBOL_GPL(queue_delayed_work_on); /** * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU * @cpu: CPU number to execute work on * @wq: workqueue to use * @dwork: work to queue * @delay: number of jiffies to wait before queueing * * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, * modify @dwork's timer so that it expires after @delay. If @delay is * zero, @work is guaranteed to be scheduled immediately regardless of its * current state. * * Returns %false if @dwork was idle and queued, %true if @dwork was * pending and its timer was modified. * * This function is safe to call from any context including IRQ handler. * See try_to_grab_pending() for details. */ bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, struct delayed_work *dwork, unsigned long delay) { unsigned long flags; int ret; do { ret = try_to_grab_pending(&dwork->work, true, &flags); } while (unlikely(ret == -EAGAIN)); if (likely(ret >= 0)) { __queue_delayed_work(cpu, wq, dwork, delay); local_irq_restore(flags); } /* -ENOENT from try_to_grab_pending() becomes %true */ return ret; } EXPORT_SYMBOL_GPL(mod_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(pool->lock). */ static void worker_enter_idle(struct worker *worker) { struct worker_pool *pool = worker->pool; if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || WARN_ON_ONCE(!list_empty(&worker->entry) && (worker->hentry.next || worker->hentry.pprev))) return; /* can't use worker_set_flags(), also called from start_worker() */ worker->flags |= WORKER_IDLE; pool->nr_idle++; worker->last_active = jiffies; /* idle_list is LIFO */ list_add(&worker->entry, &pool->idle_list); if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); /* * Sanity check nr_running. Because wq_unbind_fn() releases * pool->lock between setting %WORKER_UNBOUND and zapping * nr_running, the warning may trigger spuriously. Check iff * unbind is not in progress. */ WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && pool->nr_workers == pool->nr_idle && atomic_read(&pool->nr_running)); } /** * worker_leave_idle - leave idle state * @worker: worker which is leaving idle state * * @worker is leaving idle state. Update stats. * * LOCKING: * spin_lock_irq(pool->lock). */ static void worker_leave_idle(struct worker *worker) { struct worker_pool *pool = worker->pool; if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) return; worker_clr_flags(worker, WORKER_IDLE); pool->nr_idle--; list_del_init(&worker->entry); } /** * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it * @pool: target worker_pool * * Bind %current to the cpu of @pool if it is associated and lock @pool. * * Works which are scheduled while the cpu is online must at least be * scheduled to a worker which is bound to the cpu so that if they are * flushed from cpu callbacks while cpu is going down, they are * guaranteed to execute on the cpu. * * This function is to be used by unbound workers and rescuers to bind * themselves to the target cpu and may race with cpu going down or * coming online. kthread_bind() can't be used because it may put the * worker to already dead cpu and set_cpus_allowed_ptr() can't be used * verbatim as it's best effort and blocking and pool may be * [dis]associated in the meantime. * * This function tries set_cpus_allowed() and locks pool and verifies the * binding against %POOL_DISASSOCIATED which is set during * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker * enters idle state or fetches works without dropping lock, it can * guarantee the scheduling requirement described in the first paragraph. * * CONTEXT: * Might sleep. Called without any lock but returns with pool->lock * held. * * RETURNS: * %true if the associated pool is online (@worker is successfully * bound), %false if offline. */ static bool worker_maybe_bind_and_lock(struct worker_pool *pool) __acquires(&pool->lock) { while (true) { /* * The following call may fail, succeed or succeed * without actually migrating the task to the cpu if * it races with cpu hotunplug operation. Verify * against POOL_DISASSOCIATED. */ if (!(pool->flags & POOL_DISASSOCIATED)) set_cpus_allowed_ptr(current, pool->attrs->cpumask); spin_lock_irq(&pool->lock); if (pool->flags & POOL_DISASSOCIATED) return false; if (task_cpu(current) == pool->cpu && cpumask_equal(&current->cpus_allowed, pool->attrs->cpumask)) return true; spin_unlock_irq(&pool->lock); /* * We've raced with CPU hot[un]plug. Give it a breather * and retry migration. cond_resched() is required here; * otherwise, we might deadlock against cpu_stop trying to * bring down the CPU on non-preemptive kernel. */ cpu_relax(); cond_resched(); } } 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); /* on creation a worker is in !idle && prep state */ worker->flags = WORKER_PREP; } return worker; } /** * create_worker - create a new workqueue worker * @pool: pool the new worker will belong to * * Create a new worker which is bound to @pool. 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 worker_pool *pool) { const char *pri = pool->attrs->nice < 0 ? "H" : ""; struct worker *worker = NULL; int id = -1; lockdep_assert_held(&pool->manager_mutex); /* * ID is needed to determine kthread name. Allocate ID first * without installing the pointer. */ idr_preload(GFP_KERNEL); spin_lock_irq(&pool->lock); id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_NOWAIT); spin_unlock_irq(&pool->lock); idr_preload_end(); if (id < 0) goto fail; worker = alloc_worker(); if (!worker) goto fail; worker->pool = pool; worker->id = id; if (pool->cpu >= 0) worker->task = kthread_create_on_node(worker_thread, worker, cpu_to_node(pool->cpu), "kworker/%d:%d%s", pool->cpu, id, pri); else worker->task = kthread_create(worker_thread, worker, "kworker/u%d:%d%s", pool->id, id, pri); if (IS_ERR(worker->task)) goto fail; /* * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any * online CPUs. It'll be re-applied when any of the CPUs come up. */ set_user_nice(worker->task, pool->attrs->nice); set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); /* prevent userland from meddling with cpumask of workqueue workers */ worker->task->flags |= PF_NO_SETAFFINITY; /* * The caller is responsible for ensuring %POOL_DISASSOCIATED * remains stable across this function. See the comments above the * flag definition for details. */ if (pool->flags & POOL_DISASSOCIATED) worker->flags |= WORKER_UNBOUND; /* successful, commit the pointer to idr */ spin_lock_irq(&pool->lock); idr_replace(&pool->worker_idr, worker, worker->id); spin_unlock_irq(&pool->lock); return worker; fail: if (id >= 0) { spin_lock_irq(&pool->lock); idr_remove(&pool->worker_idr, id); spin_unlock_irq(&pool->lock); } kfree(worker); return NULL; } /** * start_worker - start a newly created worker * @worker: worker to start * * Make the pool aware of @worker and start it. * * CONTEXT: * spin_lock_irq(pool->lock). */ static void start_worker(struct worker *worker) { worker->flags |= WORKER_STARTED; worker->pool->nr_workers++; worker_enter_idle(worker); wake_up_process(worker->task); } /** * create_and_start_worker - create and start a worker for a pool * @pool: the target pool * * Grab the managership of @pool and create and start a new worker for it. */ static int create_and_start_worker(struct worker_pool *pool) { struct worker *worker; mutex_lock(&pool->manager_mutex); worker = create_worker(pool); if (worker) { spin_lock_irq(&pool->lock); start_worker(worker); spin_unlock_irq(&pool->lock); } mutex_unlock(&pool->manager_mutex); return worker ? 0 : -ENOMEM; } /** * destroy_worker - destroy a workqueue worker * @worker: worker to be destroyed * * Destroy @worker and adjust @pool stats accordingly. * * CONTEXT: * spin_lock_irq(pool->lock) which is released and regrabbed. */ static void destroy_worker(struct worker *worker) { struct worker_pool *pool = worker->pool; lockdep_assert_held(&pool->manager_mutex); lockdep_assert_held(&pool->lock); /* sanity check frenzy */ if (WARN_ON(worker->current_work) || WARN_ON(!list_empty(&worker->scheduled))) return; if (worker->flags & WORKER_STARTED) pool->nr_workers--; if (worker->flags & WORKER_IDLE) pool->nr_idle--; list_del_init(&worker->entry); worker->flags |= WORKER_DIE; idr_remove(&pool->worker_idr, worker->id); spin_unlock_irq(&pool->lock); kthread_stop(worker->task); kfree(worker); spin_lock_irq(&pool->lock); } static void idle_worker_timeout(unsigned long __pool) { struct worker_pool *pool = (void *)__pool; spin_lock_irq(&pool->lock); if (too_many_workers(pool)) { struct worker *worker; unsigned long expires; /* idle_list is kept in LIFO order, check the last one */ worker = list_entry(pool->idle_list.prev, struct worker, entry); expires = worker->last_active + IDLE_WORKER_TIMEOUT; if (time_before(jiffies, expires)) mod_timer(&pool->idle_timer, expires); else { /* it's been idle for too long, wake up manager */ pool->flags |= POOL_MANAGE_WORKERS; wake_up_worker(pool); } } spin_unlock_irq(&pool->lock); } static void send_mayday(struct work_struct *work) { struct pool_workqueue *pwq = get_work_pwq(work); struct workqueue_struct *wq = pwq->wq; lockdep_assert_held(&wq_mayday_lock); if (!wq->rescuer) return; /* mayday mayday mayday */ if (list_empty(&pwq->mayday_node)) { list_add_tail(&pwq->mayday_node, &wq->maydays); wake_up_process(wq->rescuer->task); } } static void pool_mayday_timeout(unsigned long __pool) { struct worker_pool *pool = (void *)__pool; struct work_struct *work; spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */ spin_lock(&pool->lock); if (need_to_create_worker(pool)) { /* * We've been trying to create a new worker but * haven't been successful. We might be hitting an * allocation deadlock. Send distress signals to * rescuers. */ list_for_each_entry(work, &pool->worklist, entry) send_mayday(work); } spin_unlock(&pool->lock); spin_unlock_irq(&wq_mayday_lock); mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); } /** * maybe_create_worker - create a new worker if necessary * @pool: pool to create a new worker for * * Create a new worker for @pool if necessary. @pool is guaranteed to * have at least one idle worker on return from this function. If * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is * sent to all rescuers with works scheduled on @pool to resolve * possible allocation deadlock. * * On return, need_to_create_worker() is guaranteed to be %false and * may_start_working() %true. * * LOCKING: * spin_lock_irq(pool->lock) which may be released and regrabbed * multiple times. Does GFP_KERNEL allocations. Called only from * manager. * * RETURNS: * %false if no action was taken and pool->lock stayed locked, %true * otherwise. */ static bool maybe_create_worker(struct worker_pool *pool) __releases(&pool->lock) __acquires(&pool->lock) { if (!need_to_create_worker(pool)) return false; restart: spin_unlock_irq(&pool->lock); /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); while (true) { struct worker *worker; worker = create_worker(pool); if (worker) { del_timer_sync(&pool->mayday_timer); spin_lock_irq(&pool->lock); start_worker(worker); if (WARN_ON_ONCE(need_to_create_worker(pool))) goto restart; return true; } if (!need_to_create_worker(pool)) break; __set_current_state(TASK_INTERRUPTIBLE); schedule_timeout(CREATE_COOLDOWN); if (!need_to_create_worker(pool)) break; } del_timer_sync(&pool->mayday_timer); spin_lock_irq(&pool->lock); if (need_to_create_worker(pool)) goto restart; return true; } /** * maybe_destroy_worker - destroy workers which have been idle for a while * @pool: pool to destroy workers for * * Destroy @pool workers which have been idle for longer than * IDLE_WORKER_TIMEOUT. * * LOCKING: * spin_lock_irq(pool->lock) which may be released and regrabbed * multiple times. Called only from manager. * * RETURNS: * %false if no action was taken and pool->lock stayed locked, %true * otherwise. */ static bool maybe_destroy_workers(struct worker_pool *pool) { bool ret = false; while (too_many_workers(pool)) { struct worker *worker; unsigned long expires; worker = list_entry(pool->idle_list.prev, struct worker, entry); expires = worker->last_active + IDLE_WORKER_TIMEOUT; if (time_before(jiffies, expires)) { mod_timer(&pool->idle_timer, expires); break; } destroy_worker(worker); ret = true; } return ret; } /** * manage_workers - manage worker pool * @worker: self * * Assume the manager role and manage the worker pool @worker belongs * to. At any given time, there can be only zero or one manager per * pool. The exclusion is handled automatically by this function. * * The caller can safely start processing works on false return. On * true return, it's guaranteed that need_to_create_worker() is false * and may_start_working() is true. * * CONTEXT: * spin_lock_irq(pool->lock) which may be released and regrabbed * multiple times. Does GFP_KERNEL allocations. * * RETURNS: * spin_lock_irq(pool->lock) which may be released and regrabbed * multiple times. Does GFP_KERNEL allocations. */ static bool manage_workers(struct worker *worker) { struct worker_pool *pool = worker->pool; bool ret = false; /* * Managership is governed by two mutexes - manager_arb and * manager_mutex. manager_arb handles arbitration of manager role. * Anyone who successfully grabs manager_arb wins the arbitration * and becomes the manager. mutex_trylock() on pool->manager_arb * failure while holding pool->lock reliably indicates that someone * else is managing the pool and the worker which failed trylock * can proceed to executing work items. This means that anyone * grabbing manager_arb is responsible for actually performing * manager duties. If manager_arb is grabbed and released without * actual management, the pool may stall indefinitely. * * manager_mutex is used for exclusion of actual management * operations. The holder of manager_mutex can be sure that none * of management operations, including creation and destruction of * workers, won't take place until the mutex is released. Because * manager_mutex doesn't interfere with manager role arbitration, * it is guaranteed that the pool's management, while may be * delayed, won't be disturbed by someone else grabbing * manager_mutex. */ if (!mutex_trylock(&pool->manager_arb)) return ret; /* * With manager arbitration won, manager_mutex would be free in * most cases. trylock first without dropping @pool->lock. */ if (unlikely(!mutex_trylock(&pool->manager_mutex))) { spin_unlock_irq(&pool->lock); mutex_lock(&pool->manager_mutex); ret = true; } pool->flags &= ~POOL_MANAGE_WORKERS; /* * Destroy and then create so that may_start_working() is true * on return. */ ret |= maybe_destroy_workers(pool); ret |= maybe_create_worker(pool); mutex_unlock(&pool->manager_mutex); mutex_unlock(&pool->manager_arb); return ret; } /** * 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(pool->lock) which is released and regrabbed. */ static void process_one_work(struct worker *worker, struct work_struct *work) __releases(&pool->lock) __acquires(&pool->lock) { struct pool_workqueue *pwq = get_work_pwq(work); struct worker_pool *pool = worker->pool; bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; int work_color; struct worker *collision; #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; lockdep_copy_map(&lockdep_map, &work->lockdep_map); #endif /* * Ensure we're on the correct CPU. DISASSOCIATED test is * necessary to avoid spurious warnings from rescuers servicing the * unbound or a disassociated pool. */ WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && !(pool->flags & POOL_DISASSOCIATED) && raw_smp_processor_id() != pool->cpu); /* * A single work shouldn't be executed concurrently by * multiple workers on a single cpu. Check whether anyone is * already processing the work. If so, defer the work to the * currently executing one. */ collision = find_worker_executing_work(pool, work); if (unlikely(collision)) { move_linked_works(work, &collision->scheduled, NULL); return; } /* claim and dequeue */ debug_work_deactivate(work); hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); worker->current_work = work; worker->current_func = work->func; worker->current_pwq = pwq; work_color = get_work_color(work); list_del_init(&work->entry); /* * CPU intensive works don't participate in concurrency * management. They're the scheduler's responsibility. */ if (unlikely(cpu_intensive)) worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); /* * Unbound pool isn't concurrency managed and work items should be * executed ASAP. Wake up another worker if necessary. */ if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) wake_up_worker(pool); /* * Record the last pool and clear PENDING which should be the last * update to @work. Also, do this inside @pool->lock so that * PENDING and queued state changes happen together while IRQ is * disabled. */ set_work_pool_and_clear_pending(work, pool->id); spin_unlock_irq(&pool->lock); lock_map_acquire_read(&pwq->wq->lockdep_map); lock_map_acquire(&lockdep_map); trace_workqueue_execute_start(work); worker->current_func(work); /* * While we must be careful to not use "work" after this, the trace * point will only record its address. */ trace_workqueue_execute_end(work); lock_map_release(&lockdep_map); lock_map_release(&pwq->wq->lockdep_map); if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" " last function: %pf\n", current->comm, preempt_count(), task_pid_nr(current), worker->current_func); debug_show_held_locks(current); dump_stack(); } spin_lock_irq(&pool->lock); /* clear cpu intensive status */ if (unlikely(cpu_intensive)) worker_clr_flags(worker, WORKER_CPU_INTENSIVE); /* we're done with it, release */ hash_del(&worker->hentry); worker->current_work = NULL; worker->current_func = NULL; worker->current_pwq = NULL; pwq_dec_nr_in_flight(pwq, 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(pool->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 worker thread function. All workers belong to a worker_pool - * either a per-cpu one or dynamic unbound one. These workers process all * work items regardless of their specific target workqueue. The only * exception is work items which belong to workqueues with a rescuer which * will be explained in rescuer_thread(). */ static int worker_thread(void *__worker) { struct worker *worker = __worker; struct worker_pool *pool = worker->pool; /* tell the scheduler that this is a workqueue worker */ worker->task->flags |= PF_WQ_WORKER; woke_up: spin_lock_irq(&pool->lock); /* am I supposed to die? */ if (unlikely(worker->flags & WORKER_DIE)) { spin_unlock_irq(&pool->lock); WARN_ON_ONCE(!list_empty(&worker->entry)); worker->task->flags &= ~PF_WQ_WORKER; return 0; } worker_leave_idle(worker); recheck: /* no more worker necessary? */ if (!need_more_worker(pool)) goto sleep; /* do we need to manage? */ if (unlikely(!may_start_working(pool)) && manage_workers(worker)) goto 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. */ WARN_ON_ONCE(!list_empty(&worker->scheduled)); /* * Finish PREP stage. We're guaranteed to have at least one idle * worker or that someone else has already assumed the manager * role. This is where @worker starts participating in concurrency * management if applicable and concurrency management is restored * after being rebound. See rebind_workers() for details. */ worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); do { struct work_struct *work = list_first_entry(&pool->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); } } while (keep_working(pool)); worker_set_flags(worker, WORKER_PREP, false); sleep: if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) goto recheck; /* * pool->lock is held and there's no work to process and no need to * manage, sleep. Workers are woken up only while holding * pool->lock or from local cpu, so setting the current state * before releasing pool->lock is enough to prevent losing any * event. */ worker_enter_idle(worker); __set_current_state(TASK_INTERRUPTIBLE); spin_unlock_irq(&pool->lock); schedule(); goto woke_up; } /** * rescuer_thread - the rescuer thread function * @__rescuer: self * * Workqueue rescuer thread function. There's one rescuer for each * workqueue which has WQ_MEM_RECLAIM set. * * Regular work processing on a pool may block trying to create a new * worker which uses GFP_KERNEL allocation which has slight chance of * developing into deadlock if some works currently on the same queue * need to be processed to satisfy the GFP_KERNEL allocation. This is * the problem rescuer solves. * * When such condition is possible, the pool summons rescuers of all * workqueues which have works queued on the pool and let them process * those works so that forward progress can be guaranteed. * * This should happen rarely. */ static int rescuer_thread(void *__rescuer) { struct worker *rescuer = __rescuer; struct workqueue_struct *wq = rescuer->rescue_wq; struct list_head *scheduled = &rescuer->scheduled; set_user_nice(current, RESCUER_NICE_LEVEL); /* * Mark rescuer as worker too. As WORKER_PREP is never cleared, it * doesn't participate in concurrency management. */ rescuer->task->flags |= PF_WQ_WORKER; repeat: set_current_state(TASK_INTERRUPTIBLE); if (kthread_should_stop()) { __set_current_state(TASK_RUNNING); rescuer->task->flags &= ~PF_WQ_WORKER; return 0; } /* see whether any pwq is asking for help */ spin_lock_irq(&wq_mayday_lock); while (!list_empty(&wq->maydays)) { struct pool_workqueue *pwq = list_first_entry(&wq->maydays, struct pool_workqueue, mayday_node); struct worker_pool *pool = pwq->pool; struct work_struct *work, *n; __set_current_state(TASK_RUNNING); list_del_init(&pwq->mayday_node); spin_unlock_irq(&wq_mayday_lock); /* migrate to the target cpu if possible */ worker_maybe_bind_and_lock(pool); rescuer->pool = pool; /* * Slurp in all works issued via this workqueue and * process'em. */ WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); list_for_each_entry_safe(work, n, &pool->worklist, entry) if (get_work_pwq(work) == pwq) move_linked_works(work, scheduled, &n); process_scheduled_works(rescuer); /* * Leave this pool. If keep_working() is %true, notify a * regular worker; otherwise, we end up with 0 concurrency * and stalling the execution. */ if (keep_working(pool)) wake_up_worker(pool); rescuer->pool = NULL; spin_unlock(&pool->lock); spin_lock(&wq_mayday_lock); } spin_unlock_irq(&wq_mayday_lock); /* rescuers should never participate in concurrency management */ WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); schedule(); goto repeat; } 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 * @pwq: pwq 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 pwq from @target. * * CONTEXT: * spin_lock_irq(pool->lock). */ static void insert_wq_barrier(struct pool_workqueue *pwq, 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 pool->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_ONSTACK(&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(pwq, &barr->work, head, work_color_to_flags(WORK_NO_COLOR) | linked); } /** * flush_workqueue_prep_pwqs - prepare pwqs 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 pwqs for workqueue flushing. * * If @flush_color is non-negative, flush_color on all pwqs should be * -1. If no pwq has in-flight commands at the specified color, all * pwq->flush_color's stay at -1 and %false is returned. If any pwq * has in flight commands, its pwq->flush_color is set to * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq * 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 pwqs should have the same * work_color which is previous to @work_color and all will be * advanced to @work_color. * * CONTEXT: * mutex_lock(wq->mutex). * * RETURNS: * %true if @flush_color >= 0 and there's something to flush. %false * otherwise. */ static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, int flush_color, int work_color) { bool wait = false; struct pool_workqueue *pwq; if (flush_color >= 0) { WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); atomic_set(&wq->nr_pwqs_to_flush, 1); } for_each_pwq(pwq, wq) { struct worker_pool *pool = pwq->pool; spin_lock_irq(&pool->lock); if (flush_color >= 0) { WARN_ON_ONCE(pwq->flush_color != -1); if (pwq->nr_in_flight[flush_color]) { pwq->flush_color = flush_color; atomic_inc(&wq->nr_pwqs_to_flush); wait = true; } } if (work_color >= 0) { WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); pwq->work_color = work_color; } spin_unlock_irq(&pool->lock); } if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) complete(&wq->first_flusher->done); return wait; } /** * flush_workqueue - ensure that any scheduled work has run to completion. * @wq: workqueue to flush * * This function sleeps until all work items which were queued on entry * have finished execution, but it is 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->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. */ WARN_ON_ONCE(!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 */ WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); wq->first_flusher = &this_flusher; if (!flush_workqueue_prep_pwqs(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 */ WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); list_add_tail(&this_flusher.list, &wq->flusher_queue); flush_workqueue_prep_pwqs(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->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->mutex); /* we might have raced, check again with mutex held */ if (wq->first_flusher != &this_flusher) goto out_unlock; wq->first_flusher = NULL; WARN_ON_ONCE(!list_empty(&this_flusher.list)); WARN_ON_ONCE(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); } WARN_ON_ONCE(!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_pwqs(wq, -1, wq->work_color); } if (list_empty(&wq->flusher_queue)) { WARN_ON_ONCE(wq->flush_color != wq->work_color); break; } /* * Need to flush more colors. Make the next flusher * the new first flusher and arm pwqs. */ WARN_ON_ONCE(wq->flush_color == wq->work_color); WARN_ON_ONCE(wq->flush_color != next->flush_color); list_del_init(&next->list); wq->first_flusher = next; if (flush_workqueue_prep_pwqs(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->mutex); } EXPORT_SYMBOL_GPL(flush_workqueue); /** * drain_workqueue - drain a workqueue * @wq: workqueue to drain * * Wait until the workqueue becomes empty. While draining is in progress, * only chain queueing is allowed. IOW, only currently pending or running * work items on @wq can queue further work items on it. @wq is flushed * repeatedly until it becomes empty. The number of flushing is detemined * by the depth of chaining and should be relatively short. Whine if it * takes too long. */ void drain_workqueue(struct workqueue_struct *wq) { unsigned int flush_cnt = 0; struct pool_workqueue *pwq; /* * __queue_work() needs to test whether there are drainers, is much * hotter than drain_workqueue() and already looks at @wq->flags. * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. */ mutex_lock(&wq->mutex); if (!wq->nr_drainers++) wq->flags |= __WQ_DRAINING; mutex_unlock(&wq->mutex); reflush: flush_workqueue(wq); mutex_lock(&wq->mutex); for_each_pwq(pwq, wq) { bool drained; spin_lock_irq(&pwq->pool->lock); drained = !pwq->nr_active && list_empty(&pwq->delayed_works); spin_unlock_irq(&pwq->pool->lock); if (drained) continue; if (++flush_cnt == 10 || (flush_cnt % 100 == 0 && flush_cnt <= 1000)) pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n", wq->name, flush_cnt); mutex_unlock(&wq->mutex); goto reflush; } if (!--wq->nr_drainers) wq->flags &= ~__WQ_DRAINING; mutex_unlock(&wq->mutex); } EXPORT_SYMBOL_GPL(drain_workqueue); static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) { struct worker *worker = NULL; struct worker_pool *pool; struct pool_workqueue *pwq; might_sleep(); local_irq_disable(); pool = get_work_pool(work); if (!pool) { local_irq_enable(); return false; } spin_lock(&pool->lock); /* see the comment in try_to_grab_pending() with the same code */ pwq = get_work_pwq(work); if (pwq) { if (unlikely(pwq->pool != pool)) goto already_gone; } else { worker = find_worker_executing_work(pool, work); if (!worker) goto already_gone; pwq = worker->current_pwq; } insert_wq_barrier(pwq, barr, work, worker); spin_unlock_irq(&pool->lock); /* * If @max_active is 1 or rescuer is in use, flushing another work * item on the same workqueue may lead to deadlock. Make sure the * flusher is not running on the same workqueue by verifying write * access. */ if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer) lock_map_acquire(&pwq->wq->lockdep_map); else lock_map_acquire_read(&pwq->wq->lockdep_map); lock_map_release(&pwq->wq->lockdep_map); return true; already_gone: spin_unlock_irq(&pool->lock); return false; } /** * flush_work - wait for a work to finish executing the last queueing instance * @work: the work to flush * * Wait until @work has finished execution. @work is guaranteed to be idle * on return if it hasn't been requeued since flush started. * * RETURNS: * %true if flush_work() waited for the work to finish execution, * %false if it was already idle. */ bool flush_work(struct work_struct *work) { struct wq_barrier barr; lock_map_acquire(&work->lockdep_map); lock_map_release(&work->lockdep_map); if (start_flush_work(work, &barr)) { wait_for_completion(&barr.done); destroy_work_on_stack(&barr.work); return true; } else { return false; } } EXPORT_SYMBOL_GPL(flush_work); static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) { unsigned long flags; int ret; do { ret = try_to_grab_pending(work, is_dwork, &flags); /* * If someone else is canceling, wait for the same event it * would be waiting for before retrying. */ if (unlikely(ret == -ENOENT)) flush_work(work); } while (unlikely(ret < 0)); /* tell other tasks trying to grab @work to back off */ mark_work_canceling(work); local_irq_restore(flags); flush_work(work); clear_work_data(work); return ret; } /** * cancel_work_sync - cancel a work and wait for it to finish * @work: the work to cancel * * Cancel @work and wait for its execution to finish. This function * can be used even if the work re-queues itself or migrates to * another workqueue. On return from this function, @work is * guaranteed to be not pending or executing on any CPU. * * cancel_work_sync(&delayed_work->work) must not be used for * delayed_work's. Use cancel_delayed_work_sync() instead. * * The caller must ensure that the workqueue on which @work was last * queued can't be destroyed before this function returns. * * RETURNS: * %true if @work was pending, %false otherwise. */ bool cancel_work_sync(struct work_struct *work) { return __cancel_work_timer(work, false); } EXPORT_SYMBOL_GPL(cancel_work_sync); /** * flush_delayed_work - wait for a dwork to finish executing the last queueing * @dwork: the delayed work to flush * * Delayed timer is cancelled and the pending work is queued for * immediate execution. Like flush_work(), this function only * considers the last queueing instance of @dwork. * * RETURNS: * %true if flush_work() waited for the work to finish execution, * %false if it was already idle. */ bool flush_delayed_work(struct delayed_work *dwork) { local_irq_disable(); if (del_timer_sync(&dwork->timer)) __queue_work(dwork->cpu, dwork->wq, &dwork->work); local_irq_enable(); return flush_work(&dwork->work); } EXPORT_SYMBOL(flush_delayed_work); /** * cancel_delayed_work - cancel a delayed work * @dwork: delayed_work to cancel * * Kill off a pending delayed_work. Returns %true if @dwork was pending * and canceled; %false if wasn't pending. Note that the work callback * function may still be running on return, unless it returns %true and the * work doesn't re-arm itself. Explicitly flush or use * cancel_delayed_work_sync() to wait on it. * * This function is safe to call from any context including IRQ handler. */ bool cancel_delayed_work(struct delayed_work *dwork) { unsigned long flags; int ret; do { ret = try_to_grab_pending(&dwork->work, true, &flags); } while (unlikely(ret == -EAGAIN)); if (unlikely(ret < 0)) return false; set_work_pool_and_clear_pending(&dwork->work, get_work_pool_id(&dwork->work)); local_irq_restore(flags); return ret; } EXPORT_SYMBOL(cancel_delayed_work); /** * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish * @dwork: the delayed work cancel * * This is cancel_work_sync() for delayed works. * * RETURNS: * %true if @dwork was pending, %false otherwise. */ bool cancel_delayed_work_sync(struct delayed_work *dwork) { return __cancel_work_timer(&dwork->work, true); } EXPORT_SYMBOL(cancel_delayed_work_sync); /** * schedule_on_each_cpu - execute a function synchronously on each online CPU * @func: the function to call * * schedule_on_each_cpu() executes @func on each online CPU using the * system workqueue and blocks until all CPUs have completed. * schedule_on_each_cpu() is very slow. * * RETURNS: * 0 on success, -errno on failure. */ int schedule_on_each_cpu(work_func_t func) { int cpu; struct work_struct __percpu *works; works = alloc_percpu(struct work_struct); if (!works) return -ENOMEM; get_online_cpus(); for_each_online_cpu(cpu) { struct work_struct *work = per_cpu_ptr(works, cpu); INIT_WORK(work, func); schedule_work_on(cpu, work); } 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(system_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); #ifdef CONFIG_SYSFS /* * Workqueues with WQ_SYSFS flag set is visible to userland via * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the * following attributes. * * per_cpu RO bool : whether the workqueue is per-cpu or unbound * max_active RW int : maximum number of in-flight work items * * Unbound workqueues have the following extra attributes. * * id RO int : the associated pool ID * nice RW int : nice value of the workers * cpumask RW mask : bitmask of allowed CPUs for the workers */ struct wq_device { struct workqueue_struct *wq; struct device dev; }; static struct workqueue_struct *dev_to_wq(struct device *dev) { struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); return wq_dev->wq; } static ssize_t wq_per_cpu_show(struct device *dev, struct device_attribute *attr, char *buf) { struct workqueue_struct *wq = dev_to_wq(dev); return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); } static ssize_t wq_max_active_show(struct device *dev, struct device_attribute *attr, char *buf) { struct workqueue_struct *wq = dev_to_wq(dev); return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); } static ssize_t wq_max_active_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct workqueue_struct *wq = dev_to_wq(dev); int val; if (sscanf(buf, "%d", &val) != 1 || val <= 0) return -EINVAL; workqueue_set_max_active(wq, val); return count; } static struct device_attribute wq_sysfs_attrs[] = { __ATTR(per_cpu, 0444, wq_per_cpu_show, NULL), __ATTR(max_active, 0644, wq_max_active_show, wq_max_active_store), __ATTR_NULL, }; static ssize_t wq_pool_id_show(struct device *dev, struct device_attribute *attr, char *buf) { struct workqueue_struct *wq = dev_to_wq(dev); struct worker_pool *pool; int written; rcu_read_lock_sched(); pool = first_pwq(wq)->pool; written = scnprintf(buf, PAGE_SIZE, "%d\n", pool->id); rcu_read_unlock_sched(); return written; } static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, char *buf) { struct workqueue_struct *wq = dev_to_wq(dev); int written; rcu_read_lock_sched(); written = scnprintf(buf, PAGE_SIZE, "%d\n", first_pwq(wq)->pool->attrs->nice); rcu_read_unlock_sched(); return written; } /* prepare workqueue_attrs for sysfs store operations */ static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) { struct workqueue_attrs *attrs; attrs = alloc_workqueue_attrs(GFP_KERNEL); if (!attrs) return NULL; rcu_read_lock_sched(); copy_workqueue_attrs(attrs, first_pwq(wq)->pool->attrs); rcu_read_unlock_sched(); return attrs; } static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct workqueue_struct *wq = dev_to_wq(dev); struct workqueue_attrs *attrs; int ret; attrs = wq_sysfs_prep_attrs(wq); if (!attrs) return -ENOMEM; if (sscanf(buf, "%d", &attrs->nice) == 1 && attrs->nice >= -20 && attrs->nice <= 19) ret = apply_workqueue_attrs(wq, attrs); else ret = -EINVAL; free_workqueue_attrs(attrs); return ret ?: count; } static ssize_t wq_cpumask_show(struct device *dev, struct device_attribute *attr, char *buf) { struct workqueue_struct *wq = dev_to_wq(dev); int written; rcu_read_lock_sched(); written = cpumask_scnprintf(buf, PAGE_SIZE, first_pwq(wq)->pool->attrs->cpumask); rcu_read_unlock_sched(); written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); return written; } static ssize_t wq_cpumask_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct workqueue_struct *wq = dev_to_wq(dev); struct workqueue_attrs *attrs; int ret; attrs = wq_sysfs_prep_attrs(wq); if (!attrs) return -ENOMEM; ret = cpumask_parse(buf, attrs->cpumask); if (!ret) ret = apply_workqueue_attrs(wq, attrs); free_workqueue_attrs(attrs); return ret ?: count; } static struct device_attribute wq_sysfs_unbound_attrs[] = { __ATTR(pool_id, 0444, wq_pool_id_show, NULL), __ATTR(nice, 0644, wq_nice_show, wq_nice_store), __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), __ATTR_NULL, }; static struct bus_type wq_subsys = { .name = "workqueue", .dev_attrs = wq_sysfs_attrs, }; static int __init wq_sysfs_init(void) { return subsys_virtual_register(&wq_subsys, NULL); } core_initcall(wq_sysfs_init); static void wq_device_release(struct device *dev) { struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); kfree(wq_dev); } /** * workqueue_sysfs_register - make a workqueue visible in sysfs * @wq: the workqueue to register * * Expose @wq in sysfs under /sys/bus/workqueue/devices. * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set * which is the preferred method. * * Workqueue user should use this function directly iff it wants to apply * workqueue_attrs before making the workqueue visible in sysfs; otherwise, * apply_workqueue_attrs() may race against userland updating the * attributes. * * Returns 0 on success, -errno on failure. */ int workqueue_sysfs_register(struct workqueue_struct *wq) { struct wq_device *wq_dev; int ret; /* * Adjusting max_active or creating new pwqs by applyting * attributes breaks ordering guarantee. Disallow exposing ordered * workqueues. */ if (WARN_ON(wq->flags & __WQ_ORDERED)) return -EINVAL; wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); if (!wq_dev) return -ENOMEM; wq_dev->wq = wq; wq_dev->dev.bus = &wq_subsys; wq_dev->dev.init_name = wq->name; wq_dev->dev.release = wq_device_release; /* * unbound_attrs are created separately. Suppress uevent until * everything is ready. */ dev_set_uevent_suppress(&wq_dev->dev, true); ret = device_register(&wq_dev->dev); if (ret) { kfree(wq_dev); wq->wq_dev = NULL; return ret; } if (wq->flags & WQ_UNBOUND) { struct device_attribute *attr; for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { ret = device_create_file(&wq_dev->dev, attr); if (ret) { device_unregister(&wq_dev->dev); wq->wq_dev = NULL; return ret; } } } kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); return 0; } /** * workqueue_sysfs_unregister - undo workqueue_sysfs_register() * @wq: the workqueue to unregister * * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. */ static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { struct wq_device *wq_dev = wq->wq_dev; if (!wq->wq_dev) return; wq->wq_dev = NULL; device_unregister(&wq_dev->dev); } #else /* CONFIG_SYSFS */ static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } #endif /* CONFIG_SYSFS */ /** * free_workqueue_attrs - free a workqueue_attrs * @attrs: workqueue_attrs to free * * Undo alloc_workqueue_attrs(). */ void free_workqueue_attrs(struct workqueue_attrs *attrs) { if (attrs) { free_cpumask_var(attrs->cpumask); kfree(attrs); } } /** * alloc_workqueue_attrs - allocate a workqueue_attrs * @gfp_mask: allocation mask to use * * Allocate a new workqueue_attrs, initialize with default settings and * return it. Returns NULL on failure. */ struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask) { struct workqueue_attrs *attrs; attrs = kzalloc(sizeof(*attrs), gfp_mask); if (!attrs) goto fail; if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask)) goto fail; cpumask_setall(attrs->cpumask); return attrs; fail: free_workqueue_attrs(attrs); return NULL; } static void copy_workqueue_attrs(struct workqueue_attrs *to, const struct workqueue_attrs *from) { to->nice = from->nice; cpumask_copy(to->cpumask, from->cpumask); } /* * Hacky implementation of jhash of bitmaps which only considers the * specified number of bits. We probably want a proper implementation in * include/linux/jhash.h. */ static u32 jhash_bitmap(const unsigned long *bitmap, int bits, u32 hash) { int nr_longs = bits / BITS_PER_LONG; int nr_leftover = bits % BITS_PER_LONG; unsigned long leftover = 0; if (nr_longs) hash = jhash(bitmap, nr_longs * sizeof(long), hash); if (nr_leftover) { bitmap_copy(&leftover, bitmap + nr_longs, nr_leftover); hash = jhash(&leftover, sizeof(long), hash); } return hash; } /* hash value of the content of @attr */ static u32 wqattrs_hash(const struct workqueue_attrs *attrs) { u32 hash = 0; hash = jhash_1word(attrs->nice, hash); hash = jhash_bitmap(cpumask_bits(attrs->cpumask), nr_cpu_ids, hash); return hash; } /* content equality test */ static bool wqattrs_equal(const struct workqueue_attrs *a, const struct workqueue_attrs *b) { if (a->nice != b->nice) return false; if (!cpumask_equal(a->cpumask, b->cpumask)) return false; return true; } /** * init_worker_pool - initialize a newly zalloc'd worker_pool * @pool: worker_pool to initialize * * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs. * Returns 0 on success, -errno on failure. Even on failure, all fields * inside @pool proper are initialized and put_unbound_pool() can be called * on @pool safely to release it. */ static int init_worker_pool(struct worker_pool *pool) { spin_lock_init(&pool->lock); pool->id = -1; pool->cpu = -1; pool->flags |= POOL_DISASSOCIATED; INIT_LIST_HEAD(&pool->worklist); INIT_LIST_HEAD(&pool->idle_list); hash_init(pool->busy_hash); init_timer_deferrable(&pool->idle_timer); pool->idle_timer.function = idle_worker_timeout; pool->idle_timer.data = (unsigned long)pool; setup_timer(&pool->mayday_timer, pool_mayday_timeout, (unsigned long)pool); mutex_init(&pool->manager_arb); mutex_init(&pool->manager_mutex); idr_init(&pool->worker_idr); INIT_HLIST_NODE(&pool->hash_node); pool->refcnt = 1; /* shouldn't fail above this point */ pool->attrs = alloc_workqueue_attrs(GFP_KERNEL); if (!pool->attrs) return -ENOMEM; return 0; } static void rcu_free_pool(struct rcu_head *rcu) { struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); idr_destroy(&pool->worker_idr); free_workqueue_attrs(pool->attrs); kfree(pool); } /** * put_unbound_pool - put a worker_pool * @pool: worker_pool to put * * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU * safe manner. get_unbound_pool() calls this function on its failure path * and this function should be able to release pools which went through, * successfully or not, init_worker_pool(). */ static void put_unbound_pool(struct worker_pool *pool) { struct worker *worker; mutex_lock(&wq_pool_mutex); if (--pool->refcnt) { mutex_unlock(&wq_pool_mutex); return; } /* sanity checks */ if (WARN_ON(!(pool->flags & POOL_DISASSOCIATED)) || WARN_ON(!list_empty(&pool->worklist))) { mutex_unlock(&wq_pool_mutex); return; } /* release id and unhash */ if (pool->id >= 0) idr_remove(&worker_pool_idr, pool->id); hash_del(&pool->hash_node); mutex_unlock(&wq_pool_mutex); /* * Become the manager and destroy all workers. Grabbing * manager_arb prevents @pool's workers from blocking on * manager_mutex. */ mutex_lock(&pool->manager_arb); mutex_lock(&pool->manager_mutex); spin_lock_irq(&pool->lock); while ((worker = first_worker(pool))) destroy_worker(worker); WARN_ON(pool->nr_workers || pool->nr_idle); spin_unlock_irq(&pool->lock); mutex_unlock(&pool->manager_mutex); mutex_unlock(&pool->manager_arb); /* shut down the timers */ del_timer_sync(&pool->idle_timer); del_timer_sync(&pool->mayday_timer); /* sched-RCU protected to allow dereferences from get_work_pool() */ call_rcu_sched(&pool->rcu, rcu_free_pool); } /** * get_unbound_pool - get a worker_pool with the specified attributes * @attrs: the attributes of the worker_pool to get * * Obtain a worker_pool which has the same attributes as @attrs, bump the * reference count and return it. If there already is a matching * worker_pool, it will be used; otherwise, this function attempts to * create a new one. On failure, returns NULL. */ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) { u32 hash = wqattrs_hash(attrs); struct worker_pool *pool; mutex_lock(&wq_pool_mutex); /* do we already have a matching pool? */ hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { if (wqattrs_equal(pool->attrs, attrs)) { pool->refcnt++; goto out_unlock; } } /* nope, create a new one */ pool = kzalloc(sizeof(*pool), GFP_KERNEL); if (!pool || init_worker_pool(pool) < 0) goto fail; if (workqueue_freezing) pool->flags |= POOL_FREEZING; lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ copy_workqueue_attrs(pool->attrs, attrs); if (worker_pool_assign_id(pool) < 0) goto fail; /* create and start the initial worker */ if (create_and_start_worker(pool) < 0) goto fail; /* install */ hash_add(unbound_pool_hash, &pool->hash_node, hash); out_unlock: mutex_unlock(&wq_pool_mutex); return pool; fail: mutex_unlock(&wq_pool_mutex); if (pool) put_unbound_pool(pool); return NULL; } static void rcu_free_pwq(struct rcu_head *rcu) { kmem_cache_free(pwq_cache, container_of(rcu, struct pool_workqueue, rcu)); } /* * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt * and needs to be destroyed. */ static void pwq_unbound_release_workfn(struct work_struct *work) { struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, unbound_release_work); struct workqueue_struct *wq = pwq->wq; struct worker_pool *pool = pwq->pool; if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) return; /*


context:
space:
mode: