struct timer_list idle_timer; /* L: worker idle timeout */
struct timer_list mayday_timer; /* L: SOS timer for workers */
- /* workers are chained either in busy_hash or idle_list */
+ /* 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 */
struct ida worker_ida; /* L: for worker IDs */
struct workqueue_attrs *attrs; /* I: worker attributes */
- struct hlist_node hash_node; /* R: unbound_pool_hash node */
- int refcnt; /* refcnt for unbound pools */
+ struct hlist_node hash_node; /* W: unbound_pool_hash node */
+ int refcnt; /* W: refcnt for unbound pools */
/*
* The current concurrency level. As it's likely to be accessed
struct wq_device;
/*
- * The externally visible workqueue abstraction is an array of
- * per-CPU workqueues:
+ * 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; /* W: WQ_* flags */
static struct kmem_cache *pwq_cache;
-/* hash of all unbound pools keyed by pool->attrs */
+/* W: 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;
static LIST_HEAD(workqueues);
static bool workqueue_freezing; /* W: have wqs started freezing? */
-/*
- * The CPU and unbound standard worker pools. The unbound ones have
- * POOL_DISASSOCIATED set, and their workers have WORKER_UNBOUND set.
- */
+/* the per-cpu worker pools */
static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
cpu_worker_pools);
/*
- * idr of all pools. Modifications are protected by workqueue_lock. Read
- * accesses are protected by sched-RCU protected.
+ * R: idr of all pools. Modifications are protected by workqueue_lock.
+ * Read accesses are protected by sched-RCU protected.
*/
static DEFINE_IDR(worker_pool_idr);
* 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, work function and workqueue
- * 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.
+ * 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).
get_pwq(pwq);
/*
- * Ensure either worker_sched_deactivated() 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.
+ * 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 (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);
* 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.
+ * 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
* manager.
*
* RETURNS:
- * false if no action was taken and pool->lock stayed locked, true
+ * %false if no action was taken and pool->lock stayed locked, %true
* otherwise.
*/
static bool maybe_create_worker(struct worker_pool *pool)
* multiple times. Called only from manager.
*
* RETURNS:
- * false if no action was taken and pool->lock stayed locked, true
+ * %false if no action was taken and pool->lock stayed locked, %true
* otherwise.
*/
static bool maybe_destroy_workers(struct worker_pool *pool)
* worker_thread - the worker thread function
* @__worker: self
*
- * The worker thread function. There are NR_CPU_WORKER_POOLS dynamic pools
- * of these per each cpu. These workers process all works regardless of
- * their specific target workqueue. The only exception is works which
- * belong to workqueues with a rescuer which will be explained in
- * rescuer_thread().
+ * 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)
{
* flush_workqueue - ensure that any scheduled work has run to completion.
* @wq: workqueue to flush
*
- * Forces execution of the workqueue and blocks until its completion.
- * This is typically used in driver shutdown handlers.
- *
- * We sleep until all works which were queued on entry have been handled,
- * but we are not livelocked by new incoming ones.
+ * 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)
{
if (++flush_cnt == 10 ||
(flush_cnt % 100 == 0 && flush_cnt <= 1000))
- pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n",
+ pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
wq->name, flush_cnt);
local_irq_enable();
* @pool: worker_pool to put
*
* Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
- * safe manner.
+ * 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)
{
spin_unlock_irq(&workqueue_lock);
- /* lock out manager and destroy all workers */
+ /*
+ * Become the manager and destroy all workers. Grabbing
+ * manager_arb prevents @pool's workers from blocking on
+ * manager_mutex.
+ */
mutex_lock(&pool->manager_arb);
spin_lock_irq(&pool->lock);
* freeze_workqueues_begin - begin freezing workqueues
*
* Start freezing workqueues. After this function returns, all freezable
- * workqueues will queue new works to their frozen_works list instead of
+ * workqueues will queue new works to their delayed_works list instead of
* pool->worklist.
*
* CONTEXT:
projects / firefly-linux-kernel-4.4.55.git / commitdiff