3  * kernel/workqueue.c - generic async execution with shared worker pool
25  * Please read Documentation/core-api/workqueue.rst for details.
34 #include <linux/workqueue.h>
206  * tools/workqueue/wq_monitor.py.
222  * The per-pool workqueue.  While queued, the lower WORK_STRUCT_FLAG_BITS
229 	struct workqueue_struct *wq;		/* I: the owning workqueue */
271  * Structure used to wait for workqueue flush.
282  * The externally visible workqueue.  It relays the issued work items to
314 	char			name[WQ_NAME_LEN]; /* I: workqueue name */
450 #include <trace/events/workqueue.h>
501  * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
503  * @wq: the target workqueue
992  * before the original execution finishes, workqueue will identify the
1159  * should be using an unbound workqueue instead.
1206 …printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching …  in wq_cpu_intensive_report()
1388  * As this function doesn't involve any workqueue-related locking, it
1482  * decrement nr_in_flight of its pwq and handle workqueue flushing.
1663  * same workqueue.
1690 		pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n");  in wq_select_unbound_cpu()
1723 	 * For a draining wq, only works from the same workqueue are  in __queue_work()
1783 		WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",  in __queue_work()
1817  * @wq: workqueue to use
1878  * @wq: workqueue to use
1906 	 * If this is used with a per-cpu workqueue then the logic in  in queue_work_node()
1970  * @wq: workqueue to use
2001  * @wq: workqueue to use
2048  * @wq: workqueue to use
2157  * create_worker - create a new workqueue worker
2177 		pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n",  in create_worker()
2184 		pr_err_once("workqueue: Failed to allocate a worker\n");  in create_worker()
2200 			pr_err("workqueue: Interrupted when creating a worker thread \"kworker/%s\"\n",  in create_worker()
2203 			pr_err_once("workqueue: Failed to create a worker thread: %pe",  in create_worker()
2644 		pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"  in process_one_work()
2726  * work items regardless of their specific target workqueue.  The only
2737 	/* tell the scheduler that this is a workqueue worker */  in worker_thread()
2810  * Workqueue rescuer thread function.  There's one rescuer for each
2811  * workqueue which has WQ_MEM_RECLAIM set.
2844 	 * By the time the rescuer is requested to stop, the workqueue  in rescuer_thread()
2872 		 * Slurp in all works issued via this workqueue and  in rescuer_thread()
2943  * @target_wq: workqueue being flushed
2944  * @target_work: work item being flushed (NULL for workqueue flushes)
2948  * reclaiming memory or running on a workqueue which doesn't have
2964 		  "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps",  in check_flush_dependency()
2968 		  "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps",  in check_flush_dependency()
3057  * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
3058  * @wq: workqueue being flushed
3062  * Prepare pwqs for workqueue flushing.
3129  * @wq: workqueue to flush
3286  * drain_workqueue - drain a workqueue
3287  * @wq: workqueue to drain
3289  * Wait until the workqueue becomes empty.  While draining is in progress,
3327 			pr_warn("workqueue %s: %s() isn't complete after %u tries\n",  in drain_workqueue()
3376 	 * single-threaded or rescuer equipped workqueue.  in start_flush_work()
3519  * another workqueue.  On return from this function, @work is
3525  * The caller must ensure that the workqueue on which @work was last
3647  * system workqueue and blocks until all CPUs have completed.
3766  * Some attrs fields are workqueue-only. Clear them for worker_pool's. See the
4150  * workqueue's saved_max_active and activate inactive work items
4253  * @attrs: the wq_attrs of the default pwq of the target workqueue
4257  * Calculate the cpumask a workqueue with @attrs should use on @pod. If
4288 		pr_warn_once("WARNING: workqueue cpumask: online intersect > "  in wq_calc_pod_cpumask()
4311 	struct workqueue_struct	*wq;		/* target workqueue */
4446  * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
4447  * @wq: the target workqueue
4450  * Apply @attrs to an unbound workqueue @wq. Unless disabled, this function maps
4478  * @wq: the target workqueue
4491  * Note that when the last allowed CPU of a pod goes offline for a workqueue
4493  * executing the work items for the workqueue will lose their CPU affinity and
4495  * CPU_DOWN. If a workqueue user wants strict affinity, it's the user's
4530 		pr_warn("workqueue: allocation failed while updating CPU pod affinity of \"%s\"\n",  in wq_update_pod()
4587 		     "ordering guarantee broken for workqueue %s\n", wq->name);  in alloc_and_link_pwqs()
4619 		pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",  in wq_clamp_max_active()
4639 		pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n",  in init_rescuer()
4648 		pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe",  in init_rescuer()
4674 	 * workqueue, keep the previous behavior to avoid subtle breakages.  in alloc_workqueue()
4771  * destroy_workqueue - safely terminate a workqueue
4772  * @wq: target workqueue
4774  * Safely destroy a workqueue. All work currently pending will be done first.
4787 	/* mark the workqueue destruction is in progress */  in destroy_workqueue()
4859  * workqueue_set_max_active - adjust max_active of a workqueue
4860  * @wq: target workqueue
4893  * Determine if %current task is a workqueue worker and what it's working on.
4896  * Return: work struct if %current task is a workqueue worker, %NULL otherwise.
4907  * current_is_workqueue_rescuer - is %current workqueue rescuer?
4909  * Determine whether %current is a workqueue rescuer.  Can be used from
4912  * Return: %true if %current is a workqueue rescuer. %false otherwise.
4922  * workqueue_congested - test whether a workqueue is congested
4924  * @wq: target workqueue
4926  * Test whether @wq's cpu workqueue for @cpu is congested.  There is
4933  * pool_workqueues, each with its own congested state. A workqueue being
4934  * congested on one CPU doesn't mean that the workqueue is contested on any
5024  * name of the workqueue being serviced and worker description set with
5050 	 * Carefully copy the associated workqueue's workfn, name and desc.  in print_worker_info()
5196  * show_one_workqueue - dump state of specified workqueue
5197  * @wq: workqueue whose state will be printed
5211 	if (idle) /* Nothing to print for idle workqueue */  in show_one_workqueue()
5214 	pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags);  in show_one_workqueue()
5289  * show_all_workqueues - dump workqueue state
5313  * show_freezable_workqueues - dump freezable workqueue state
5842 	 * by any subsequent write to workqueue/cpumask sysfs file.  in workqueue_unbound_exclude_cpumask()
5908  * /sys/bus/workqueue/devices/WQ_NAME.  All visible workqueues have the
5911  *  per_cpu		RO bool	: whether the workqueue is per-cpu or unbound
6157 	.name				= "workqueue",
6286  * workqueue_sysfs_register - make a workqueue visible in sysfs
6287  * @wq: the workqueue to register
6289  * Expose @wq in sysfs under /sys/bus/workqueue/devices.
6293  * Workqueue user should use this function directly iff it wants to apply
6294  * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
6355  * @wq: the workqueue to unregister
6374  * Workqueue watchdog.
6378  * indefinitely.  Workqueue stalls can be very difficult to debug as the
6379  * usual warning mechanisms don't trigger and internal workqueue state is
6382  * Workqueue watchdog monitors all worker pools periodically and dumps
6387  * "workqueue.watchdog_thresh" which can be updated at runtime through the
6504 			pr_emerg("BUG: workqueue lockup - pool");  in wq_watchdog_timer_fn()
6586 		pr_warn("workqueue: Restricting unbound_cpumask (%*pb) with %s (%*pb) leaves no CPU, ignoring\n",  in restrict_unbound_cpumask()
6595  * workqueue_init_early - early init for workqueue subsystem
6597  * This is the first step of three-staged workqueue subsystem initialization and
6620 		restrict_unbound_cpumask("workqueue.unbound_cpus", &wq_cmdline_cpumask);  in workqueue_init_early()
6739  * workqueue_init - bring workqueue subsystem fully online
6741  * This is the second step of three-staged workqueue subsystem initialization
6769 		     "workqueue: failed to create early rescuer for %s",  in workqueue_init()
6855  * This is the third step of there-staged workqueue subsystem initialization and
6873 	 * worker pool. Explicitly call wq_update_pod() on all workqueue and CPU  in workqueue_init_topology()
6896 		pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n");  in workqueue_unbound_cpus_setup()
6901 __setup("workqueue.unbound_cpus=", workqueue_unbound_cpus_setup);