/* Worker thread pool for slow items, such as filesystem lookups or mkdirs * * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. * * See Documentation/slow-work.txt */ #ifndef _LINUX_SLOW_WORK_H #define _LINUX_SLOW_WORK_H #ifdef CONFIG_SLOW_WORK #include <linux/sysctl.h> #include <linux/timer.h> struct slow_work; #ifdef CONFIG_SLOW_WORK_DEBUG struct seq_file; #endif /* * The operations used to support slow work items */ struct slow_work_ops { /* owner */ struct module *owner; /* get a ref on a work item * - return 0 if successful, -ve if not */ int (*get_ref)(struct slow_work *work); /* discard a ref to a work item */ void (*put_ref)(struct slow_work *work); /* execute a work item */ void (*execute)(struct slow_work *work); #ifdef CONFIG_SLOW_WORK_DEBUG /* describe a work item for debugfs */ void (*desc)(struct slow_work *work, struct seq_file *m); #endif }; /* * A slow work item * - A reference is held on the parent object by the thread pool when it is * queued */ struct slow_work { struct module *owner; /* the owning module */ unsigned long flags; #define SLOW_WORK_PENDING 0 /* item pending (further) execution */ #define SLOW_WORK_EXECUTING 1 /* item currently executing */ #define SLOW_WORK_ENQ_DEFERRED 2 /* item enqueue deferred */ #define SLOW_WORK_VERY_SLOW 3 /* item is very slow */ #define SLOW_WORK_CANCELLING 4 /* item is being cancelled, don't enqueue */ #define SLOW_WORK_DELAYED 5 /* item is struct delayed_slow_work with active timer */ const struct slow_work_ops *ops; /* operations table for this item */ struct list_head link; /* link in queue */ #ifdef CONFIG_SLOW_WORK_DEBUG struct timespec mark; /* jiffies at which queued or exec begun */ #endif }; struct delayed_slow_work { struct slow_work work; struct timer_list timer; }; /** * slow_work_init - Initialise a slow work item * @work: The work item to initialise * @ops: The operations to use to handle the slow work item * * Initialise a slow work item. */ static inline void slow_work_init(struct slow_work *work, const struct slow_work_ops *ops) { work->flags = 0; work->ops = ops; INIT_LIST_HEAD(&work->link); } /** * slow_work_init - Initialise a delayed slow work item * @work: The work item to initialise * @ops: The operations to use to handle the slow work item * * Initialise a delayed slow work item. */ static inline void delayed_slow_work_init(struct delayed_slow_work *dwork, const struct slow_work_ops *ops) { init_timer(&dwork->timer); slow_work_init(&dwork->work, ops); } /** * vslow_work_init - Initialise a very slow work item * @work: The work item to initialise * @ops: The operations to use to handle the slow work item * * Initialise a very slow work item. This item will be restricted such that * only a certain number of the pool threads will be able to execute items of * this type. */ static inline void vslow_work_init(struct slow_work *work, const struct slow_work_ops *ops) { work->flags = 1 << SLOW_WORK_VERY_SLOW; work->ops = ops; INIT_LIST_HEAD(&work->link); } /** * slow_work_is_queued - Determine if a slow work item is on the work queue * work: The work item to test * * Determine if the specified slow-work item is on the work queue. This * returns true if it is actually on the queue. * * If the item is executing and has been marked for requeue when execution * finishes, then false will be returned. * * Anyone wishing to wait for completion of execution can wait on the * SLOW_WORK_EXECUTING bit. */ static inline bool slow_work_is_queued(struct slow_work *work) { unsigned long flags = work->flags; return flags & SLOW_WORK_PENDING && !(flags & SLOW_WORK_EXECUTING); } extern int slow_work_enqueue(struct slow_work *work); extern void slow_work_cancel(struct slow_work *work); extern int slow_work_register_user(struct module *owner); extern void slow_work_unregister_user(struct module *owner); extern int delayed_slow_work_enqueue(struct delayed_slow_work *dwork, unsigned long delay); static inline void delayed_slow_work_cancel(struct delayed_slow_work *dwork) { slow_work_cancel(&dwork->work); } extern bool slow_work_sleep_till_thread_needed(struct slow_work *work, signed long *_timeout); #ifdef CONFIG_SYSCTL extern ctl_table slow_work_sysctls[]; #endif #endif /* CONFIG_SLOW_WORK */ #endif /* _LINUX_SLOW_WORK_H */