0160950297
Add support for cancellation of queued slow work and delayed slow work items. The cancellation functions will wait for items that are pending or undergoing execution to be discarded by the slow work facility. Attempting to enqueue work that is in the process of being cancelled will result in ECANCELED. Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com>
102 lines
2.8 KiB
C
102 lines
2.8 KiB
C
/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*
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* See Documentation/slow-work.txt
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*/
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#ifndef _LINUX_SLOW_WORK_H
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#define _LINUX_SLOW_WORK_H
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#ifdef CONFIG_SLOW_WORK
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#include <linux/sysctl.h>
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struct slow_work;
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/*
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* The operations used to support slow work items
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*/
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struct slow_work_ops {
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/* owner */
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struct module *owner;
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/* get a ref on a work item
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* - return 0 if successful, -ve if not
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*/
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int (*get_ref)(struct slow_work *work);
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/* discard a ref to a work item */
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void (*put_ref)(struct slow_work *work);
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/* execute a work item */
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void (*execute)(struct slow_work *work);
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};
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/*
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* A slow work item
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* - A reference is held on the parent object by the thread pool when it is
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* queued
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*/
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struct slow_work {
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struct module *owner; /* the owning module */
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unsigned long flags;
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#define SLOW_WORK_PENDING 0 /* item pending (further) execution */
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#define SLOW_WORK_EXECUTING 1 /* item currently executing */
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#define SLOW_WORK_ENQ_DEFERRED 2 /* item enqueue deferred */
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#define SLOW_WORK_VERY_SLOW 3 /* item is very slow */
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#define SLOW_WORK_CANCELLING 4 /* item is being cancelled, don't enqueue */
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const struct slow_work_ops *ops; /* operations table for this item */
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struct list_head link; /* link in queue */
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};
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/**
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* slow_work_init - Initialise a slow work item
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* @work: The work item to initialise
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* @ops: The operations to use to handle the slow work item
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*
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* Initialise a slow work item.
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*/
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static inline void slow_work_init(struct slow_work *work,
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const struct slow_work_ops *ops)
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{
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work->flags = 0;
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work->ops = ops;
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INIT_LIST_HEAD(&work->link);
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}
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/**
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* vslow_work_init - Initialise a very slow work item
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* @work: The work item to initialise
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* @ops: The operations to use to handle the slow work item
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*
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* Initialise a very slow work item. This item will be restricted such that
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* only a certain number of the pool threads will be able to execute items of
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* this type.
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*/
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static inline void vslow_work_init(struct slow_work *work,
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const struct slow_work_ops *ops)
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{
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work->flags = 1 << SLOW_WORK_VERY_SLOW;
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work->ops = ops;
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INIT_LIST_HEAD(&work->link);
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}
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extern int slow_work_enqueue(struct slow_work *work);
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extern void slow_work_cancel(struct slow_work *work);
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extern int slow_work_register_user(struct module *owner);
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extern void slow_work_unregister_user(struct module *owner);
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#ifdef CONFIG_SYSCTL
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extern ctl_table slow_work_sysctls[];
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#endif
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#endif /* CONFIG_SLOW_WORK */
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#endif /* _LINUX_SLOW_WORK_H */
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