3  * kernel/workqueue.c - generic async execution with shared worker pool
25  * Please read Documentation/core-api/workqueue.rst for details.
35 #include <linux/workqueue.h>
235  * tools/workqueue/wq_monitor.py.
251  * The per-pool workqueue.  While queued, bits below WORK_PWQ_SHIFT
258 	struct workqueue_struct *wq;		/* I: the owning workqueue */
301  * Structure used to wait for workqueue flush.
312  * Unlike in a per-cpu workqueue where max_active limits its concurrency level
313  * on each CPU, in an unbound workqueue, max_active applies to the whole system.
332  * The externally visible workqueue.  It relays the issued work items to
370 	char			name[WQ_NAME_LEN]; /* I: workqueue name */
531 #include <trace/events/workqueue.h>
587  * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
589  * @wq: the target workqueue
739  * unbound_effective_cpumask - effective cpumask of an unbound workqueue
740  * @wq: workqueue of interest
1091  * before the original execution finishes, workqueue will identify the
1290  * should be using an unbound workqueue instead.
1339 …printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching …  in wq_cpu_intensive_report()
1523  * As this function doesn't involve any workqueue-related locking, it
1541  * @wq: workqueue of interest
1566  * @wq: workqueue to update
1720 		/* BH or per-cpu workqueue, pwq->nr_active is sufficient */  in pwq_tryinc_nr_active()
1729 	 * Unbound workqueue uses per-node shared nr_active $nna. If @pwq is  in pwq_tryinc_nr_active()
1944 	 * For a percpu workqueue, it's simple. Just need to kick the first  in pwq_dec_nr_active()
1953 	 * If @pwq is for an unbound workqueue, it's more complicated because  in pwq_dec_nr_active()
1979  * decrement nr_in_flight of its pwq and handle workqueue flushing.
2193  * same workqueue.
2220 		pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n");  in wq_select_unbound_cpu()
2252 	 * For a draining wq, only works from the same workqueue are  in __queue_work()
2277 	 * For ordered workqueue, work items must be queued on the newest pwq  in __queue_work()
2316 		WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",  in __queue_work()
2369  * @wq: workqueue to use
2431  * @wq: workqueue to use
2459 	 * If this is used with a per-cpu workqueue then the logic in  in queue_work_node()
2532  * @wq: workqueue to use
2564  * @wq: workqueue to use
2607  * @wq: workqueue to use
2757  * create_worker - create a new workqueue worker
2776 		pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n",  in create_worker()
2783 		pr_err_once("workqueue: Failed to allocate a worker\n");  in create_worker()
2797 				pr_err("workqueue: Interrupted when creating a worker thread \"%s\"\n",  in create_worker()
2800 				pr_err_once("workqueue: Failed to create a worker thread: %pe",  in create_worker()
3243 		pr_err("BUG: workqueue leaked atomic, lock or RCU: %s[%d]\n"  in process_one_work()
3330  * work items regardless of their specific target workqueue.  The only
3341 	/* tell the scheduler that this is a workqueue worker */  in worker_thread()
3414  * Workqueue rescuer thread function.  There's one rescuer for each
3415  * workqueue which has WQ_MEM_RECLAIM set.
3448 	 * By the time the rescuer is requested to stop, the workqueue  in rescuer_thread()
3476 		 * Slurp in all works issued via this workqueue and  in rescuer_thread()
3582  * TODO: Convert all tasklet users to workqueue and use softirq directly.
3681  * @target_wq: workqueue being flushed
3682  * @target_work: work item being flushed (NULL for workqueue flushes)
3686  * reclaiming memory or running on a workqueue which doesn't have
3702 		  "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps",  in check_flush_dependency()
3706 		  "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps",  in check_flush_dependency()
3801  * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
3802  * @wq: workqueue being flushed
3806  * Prepare pwqs for workqueue flushing.
3905  * @wq: workqueue to flush
4061  * drain_workqueue - drain a workqueue
4062  * @wq: workqueue to drain
4064  * Wait until the workqueue becomes empty.  While draining is in progress,
4102 			pr_warn("workqueue %s: %s() isn't complete after %u tries\n",  in drain_workqueue()
4153 	 * single-threaded or rescuer equipped workqueue.  in start_flush_work()
4188 	 * was queued on a BH workqueue, we also know that it was running in the  in __flush_work()
4291 		WARN_ONCE(true, "workqueue: work disable count overflowed\n");  in work_offqd_disable()
4299 		WARN_ONCE(true, "workqueue: work disable count underflowed\n");  in work_offqd_enable()
4359  * even if the work re-queues itself or migrates to another workqueue. On return
4367  * workqueue. Can also be called from non-hardirq atomic contexts including BH
4368  * if @work was last queued on a BH workqueue.
4441  * workqueue. Can also be called from non-hardirq atomic contexts including BH
4442  * if @work was last queued on a BH workqueue.
4522  * system workqueue and blocks until all CPUs have completed.
4641  * Some attrs fields are workqueue-only. Clear them for worker_pool's. See the
5055 		 * For ordered workqueue with a plugged dfl_pwq, restart it now.  in pwq_release_workfn()
5162  * @attrs: the wq_attrs of the default pwq of the target workqueue
5165  * Calculate the cpumask a workqueue with @attrs should use on @pod.
5208 	struct workqueue_struct	*wq;		/* target workqueue */
5349  * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
5350  * @wq: the target workqueue
5353  * Apply @attrs to an unbound workqueue @wq. Unless disabled, this function maps
5377  * @wq: the target workqueue
5387  * Note that when the last allowed CPU of a pod goes offline for a workqueue
5389  * executing the work items for the workqueue will lose their CPU affinity and
5391  * CPU_DOWN. If a workqueue user wants strict affinity, it's the user's
5422 		pr_warn("workqueue: allocation failed while updating CPU pod affinity of \"%s\"\n",  in unbound_wq_update_pwq()
5492 		     "ordering guarantee broken for workqueue %s\n", wq->name);  in alloc_and_link_pwqs()
5517 		pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",  in wq_clamp_max_active()
5540 		pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n",  in init_rescuer()
5551 		pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe",  in init_rescuer()
5569  * @wq: target workqueue
5668 		pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n",  in __alloc_workqueue()
5808  * destroy_workqueue - safely terminate a workqueue
5809  * @wq: target workqueue
5811  * Safely destroy a workqueue. All work currently pending will be done first.
5824 	/* mark the workqueue destruction is in progress */  in destroy_workqueue()
5895  * workqueue_set_max_active - adjust max_active of a workqueue
5896  * @wq: target workqueue
5929  * workqueue_set_min_active - adjust min_active of an unbound workqueue
5930  * @wq: target unbound workqueue
5933  * Set min_active of an unbound workqueue. Unlike other types of workqueues, an
5934  * unbound workqueue is not guaranteed to be able to process max_active
5935  * interdependent work items. Instead, an unbound workqueue is guaranteed to be
5958  * Determine if %current task is a workqueue worker and what it's working on.
5961  * Return: work struct if %current task is a workqueue worker, %NULL otherwise.
5972  * current_is_workqueue_rescuer - is %current workqueue rescuer?
5974  * Determine whether %current is a workqueue rescuer.  Can be used from
5977  * Return: %true if %current is a workqueue rescuer. %false otherwise.
5987  * workqueue_congested - test whether a workqueue is congested
5989  * @wq: target workqueue
5991  * Test whether @wq's cpu workqueue for @cpu is congested.  There is
5998  * pool_workqueues, each with its own congested state. A workqueue being
5999  * congested on one CPU doesn't mean that the workqueue is contested on any
6089  * name of the workqueue being serviced and worker description set with
6115 	 * Carefully copy the associated workqueue's workfn, name and desc.  in print_worker_info()
6277  * show_one_workqueue - dump state of specified workqueue
6278  * @wq: workqueue whose state will be printed
6292 	if (idle) /* Nothing to print for idle workqueue */  in show_one_workqueue()
6295 	pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags);  in show_one_workqueue()
6370  * show_all_workqueues - dump workqueue state
6394  * show_freezable_workqueues - dump freezable workqueue state
6924 	 * by any subsequent write to workqueue/cpumask sysfs file.  in workqueue_unbound_exclude_cpumask()
6993  * /sys/bus/workqueue/devices/WQ_NAME.  All visible workqueues have the
6996  *  per_cpu		RO bool	: whether the workqueue is per-cpu or unbound
7229 	.name				= "workqueue",
7339  * workqueue_sysfs_register - make a workqueue visible in sysfs
7340  * @wq: the workqueue to register
7342  * Expose @wq in sysfs under /sys/bus/workqueue/devices.
7346  * Workqueue user should use this function directly iff it wants to apply
7347  * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
7407  * @wq: the workqueue to unregister
7426  * Workqueue watchdog.
7430  * indefinitely.  Workqueue stalls can be very difficult to debug as the
7431  * usual warning mechanisms don't trigger and internal workqueue state is
7434  * Workqueue watchdog monitors all worker pools periodically and dumps
7439  * "workqueue.watchdog_thresh" which can be updated at runtime through the
7569 			pr_emerg("BUG: workqueue lockup - pool");  in wq_watchdog_timer_fn()
7672 		pr_warn("workqueue: Restricting unbound_cpumask (%*pb) with %s (%*pb) leaves no CPU, ignoring\n",  in restrict_unbound_cpumask()
7697  * workqueue_init_early - early init for workqueue subsystem
7699  * This is the first step of three-staged workqueue subsystem initialization and
7726 		restrict_unbound_cpumask("workqueue.unbound_cpus", &wq_cmdline_cpumask);  in workqueue_init_early()
7736 	 * If nohz_full is enabled, set power efficient workqueue as unbound.  in workqueue_init_early()
7737 	 * This allows workqueue items to be moved to HK CPUs.  in workqueue_init_early()
7852  * workqueue_init - bring workqueue subsystem fully online
7854  * This is the second step of three-staged workqueue subsystem initialization
7883 		     "workqueue: failed to create early rescuer for %s",  in workqueue_init()
7978  * This is the third step of three-staged workqueue subsystem initialization and
7998 	 * worker pool. Explicitly call unbound_wq_update_pwq() on all workqueue  in workqueue_init_topology()
8025 		pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n");  in workqueue_unbound_cpus_setup()
8030 __setup("workqueue.unbound_cpus=", workqueue_unbound_cpus_setup);