slow-work: kill it

slow-work doesn't have any user left.  Kill it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David Howells <dhowells@redhat.com>

1 files changed, 0 insertions, 1068 deletions

diff --git a/kernel/slow-work.c b/kernel/slow-work.c
deleted file mode 100644
index 7d3f4fa9ef4f..000000000000
--- a/kernel/slow-work.c
+++ /dev/null
@@ -1,1068 +0,0 @@
-/* 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
- */
-
-#include <linux/module.h>
-#include <linux/slow-work.h>
-#include <linux/kthread.h>
-#include <linux/freezer.h>
-#include <linux/wait.h>
-#include <linux/debugfs.h>
-#include "slow-work.h"
-
-static void slow_work_cull_timeout(unsigned long);
-static void slow_work_oom_timeout(unsigned long);
-
-#ifdef CONFIG_SYSCTL
-static int slow_work_min_threads_sysctl(struct ctl_table *, int,
-					void __user *, size_t *, loff_t *);
-
-static int slow_work_max_threads_sysctl(struct ctl_table *, int ,
-					void __user *, size_t *, loff_t *);
-#endif
-
-/*
- * The pool of threads has at least min threads in it as long as someone is
- * using the facility, and may have as many as max.
- *
- * A portion of the pool may be processing very slow operations.
- */
-static unsigned slow_work_min_threads = 2;
-static unsigned slow_work_max_threads = 4;
-static unsigned vslow_work_proportion = 50; /* % of threads that may process
-					     * very slow work */
-
-#ifdef CONFIG_SYSCTL
-static const int slow_work_min_min_threads = 2;
-static int slow_work_max_max_threads = SLOW_WORK_THREAD_LIMIT;
-static const int slow_work_min_vslow = 1;
-static const int slow_work_max_vslow = 99;
-
-ctl_table slow_work_sysctls[] = {
-	{
-		.procname	= "min-threads",
-		.data		= &slow_work_min_threads,
-		.maxlen		= sizeof(unsigned),
-		.mode		= 0644,
-		.proc_handler	= slow_work_min_threads_sysctl,
-		.extra1		= (void *) &slow_work_min_min_threads,
-		.extra2		= &slow_work_max_threads,
-	},
-	{
-		.procname	= "max-threads",
-		.data		= &slow_work_max_threads,
-		.maxlen		= sizeof(unsigned),
-		.mode		= 0644,
-		.proc_handler	= slow_work_max_threads_sysctl,
-		.extra1		= &slow_work_min_threads,
-		.extra2		= (void *) &slow_work_max_max_threads,
-	},
-	{
-		.procname	= "vslow-percentage",
-		.data		= &vslow_work_proportion,
-		.maxlen		= sizeof(unsigned),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *) &slow_work_min_vslow,
-		.extra2		= (void *) &slow_work_max_vslow,
-	},
-	{}
-};
-#endif
-
-/*
- * The active state of the thread pool
- */
-static atomic_t slow_work_thread_count;
-static atomic_t vslow_work_executing_count;
-
-static bool slow_work_may_not_start_new_thread;
-static bool slow_work_cull; /* cull a thread due to lack of activity */
-static DEFINE_TIMER(slow_work_cull_timer, slow_work_cull_timeout, 0, 0);
-static DEFINE_TIMER(slow_work_oom_timer, slow_work_oom_timeout, 0, 0);
-static struct slow_work slow_work_new_thread; /* new thread starter */
-
-/*
- * slow work ID allocation (use slow_work_queue_lock)
- */
-static DECLARE_BITMAP(slow_work_ids, SLOW_WORK_THREAD_LIMIT);
-
-/*
- * Unregistration tracking to prevent put_ref() from disappearing during module
- * unload
- */
-#ifdef CONFIG_MODULES
-static struct module *slow_work_thread_processing[SLOW_WORK_THREAD_LIMIT];
-static struct module *slow_work_unreg_module;
-static struct slow_work *slow_work_unreg_work_item;
-static DECLARE_WAIT_QUEUE_HEAD(slow_work_unreg_wq);
-static DEFINE_MUTEX(slow_work_unreg_sync_lock);
-
-static void slow_work_set_thread_processing(int id, struct slow_work *work)
-{
-	if (work)
-		slow_work_thread_processing[id] = work->owner;
-}
-static void slow_work_done_thread_processing(int id, struct slow_work *work)
-{
-	struct module *module = slow_work_thread_processing[id];
-
-	slow_work_thread_processing[id] = NULL;
-	smp_mb();
-	if (slow_work_unreg_work_item == work ||
-	    slow_work_unreg_module == module)
-		wake_up_all(&slow_work_unreg_wq);
-}
-static void slow_work_clear_thread_processing(int id)
-{
-	slow_work_thread_processing[id] = NULL;
-}
-#else
-static void slow_work_set_thread_processing(int id, struct slow_work *work) {}
-static void slow_work_done_thread_processing(int id, struct slow_work *work) {}
-static void slow_work_clear_thread_processing(int id) {}
-#endif
-
-/*
- * Data for tracking currently executing items for indication through /proc
- */
-#ifdef CONFIG_SLOW_WORK_DEBUG
-struct slow_work *slow_work_execs[SLOW_WORK_THREAD_LIMIT];
-pid_t slow_work_pids[SLOW_WORK_THREAD_LIMIT];
-DEFINE_RWLOCK(slow_work_execs_lock);
-#endif
-
-/*
- * The queues of work items and the lock governing access to them.  These are
- * shared between all the CPUs.  It doesn't make sense to have per-CPU queues
- * as the number of threads bears no relation to the number of CPUs.
- *
- * There are two queues of work items: one for slow work items, and one for
- * very slow work items.
- */
-LIST_HEAD(slow_work_queue);
-LIST_HEAD(vslow_work_queue);
-DEFINE_SPINLOCK(slow_work_queue_lock);
-
-/*
- * The following are two wait queues that get pinged when a work item is placed
- * on an empty queue.  These allow work items that are hogging a thread by
- * sleeping in a way that could be deferred to yield their thread and enqueue
- * themselves.
- */
-static DECLARE_WAIT_QUEUE_HEAD(slow_work_queue_waits_for_occupation);
-static DECLARE_WAIT_QUEUE_HEAD(vslow_work_queue_waits_for_occupation);
-
-/*
- * The thread controls.  A variable used to signal to the threads that they
- * should exit when the queue is empty, a waitqueue used by the threads to wait
- * for signals, and a completion set by the last thread to exit.
- */
-static bool slow_work_threads_should_exit;
-static DECLARE_WAIT_QUEUE_HEAD(slow_work_thread_wq);
-static DECLARE_COMPLETION(slow_work_last_thread_exited);
-
-/*
- * The number of users of the thread pool and its lock.  Whilst this is zero we
- * have no threads hanging around, and when this reaches zero, we wait for all
- * active or queued work items to complete and kill all the threads we do have.
- */
-static int slow_work_user_count;
-static DEFINE_MUTEX(slow_work_user_lock);
-
-static inline int slow_work_get_ref(struct slow_work *work)
-{
-	if (work->ops->get_ref)
-		return work->ops->get_ref(work);
-
-	return 0;
-}
-
-static inline void slow_work_put_ref(struct slow_work *work)
-{
-	if (work->ops->put_ref)
-		work->ops->put_ref(work);
-}
-
-/*
- * Calculate the maximum number of active threads in the pool that are
- * permitted to process very slow work items.
- *
- * The answer is rounded up to at least 1, but may not equal or exceed the
- * maximum number of the threads in the pool.  This means we always have at
- * least one thread that can process slow work items, and we always have at
- * least one thread that won't get tied up doing so.
- */
-static unsigned slow_work_calc_vsmax(void)
-{
-	unsigned vsmax;
-
-	vsmax = atomic_read(&slow_work_thread_count) * vslow_work_proportion;
-	vsmax /= 100;
-	vsmax = max(vsmax, 1U);
-	return min(vsmax, slow_work_max_threads - 1);
-}
-
-/*
- * Attempt to execute stuff queued on a slow thread.  Return true if we managed
- * it, false if there was nothing to do.
- */
-static noinline bool slow_work_execute(int id)
-{
-	struct slow_work *work = NULL;
-	unsigned vsmax;
-	bool very_slow;
-
-	vsmax = slow_work_calc_vsmax();
-
-	/* see if we can schedule a new thread to be started if we're not
-	 * keeping up with the work */
-	if (!waitqueue_active(&slow_work_thread_wq) &&
-	    (!list_empty(&slow_work_queue) || !list_empty(&vslow_work_queue)) &&
-	    atomic_read(&slow_work_thread_count) < slow_work_max_threads &&
-	    !slow_work_may_not_start_new_thread)
-		slow_work_enqueue(&slow_work_new_thread);
-
-	/* find something to execute */
-	spin_lock_irq(&slow_work_queue_lock);
-	if (!list_empty(&vslow_work_queue) &&
-	    atomic_read(&vslow_work_executing_count) < vsmax) {
-		work = list_entry(vslow_work_queue.next,
-				  struct slow_work, link);
-		if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags))
-			BUG();
-		list_del_init(&work->link);
-		atomic_inc(&vslow_work_executing_count);
-		very_slow = true;
-	} else if (!list_empty(&slow_work_queue)) {
-		work = list_entry(slow_work_queue.next,
-				  struct slow_work, link);
-		if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags))
-			BUG();
-		list_del_init(&work->link);
-		very_slow = false;
-	} else {
-		very_slow = false; /* avoid the compiler warning */
-	}
-
-	slow_work_set_thread_processing(id, work);
-	if (work) {
-		slow_work_mark_time(work);
-		slow_work_begin_exec(id, work);
-	}
-
-	spin_unlock_irq(&slow_work_queue_lock);
-
-	if (!work)
-		return false;
-
-	if (!test_and_clear_bit(SLOW_WORK_PENDING, &work->flags))
-		BUG();
-
-	/* don't execute if the work is in the process of being cancelled */
-	if (!test_bit(SLOW_WORK_CANCELLING, &work->flags))
-		work->ops->execute(work);
-
-	if (very_slow)
-		atomic_dec(&vslow_work_executing_count);
-	clear_bit_unlock(SLOW_WORK_EXECUTING, &work->flags);
-
-	/* wake up anyone waiting for this work to be complete */
-	wake_up_bit(&work->flags, SLOW_WORK_EXECUTING);
-
-	slow_work_end_exec(id, work);
-
-	/* if someone tried to enqueue the item whilst we were executing it,
-	 * then it'll be left unenqueued to avoid multiple threads trying to
-	 * execute it simultaneously
-	 *
-	 * there is, however, a race between us testing the pending flag and
-	 * getting the spinlock, and between the enqueuer setting the pending
-	 * flag and getting the spinlock, so we use a deferral bit to tell us
-	 * if the enqueuer got there first
-	 */
-	if (test_bit(SLOW_WORK_PENDING, &work->flags)) {
-		spin_lock_irq(&slow_work_queue_lock);
-
-		if (!test_bit(SLOW_WORK_EXECUTING, &work->flags) &&
-		    test_and_clear_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags))
-			goto auto_requeue;
-
-		spin_unlock_irq(&slow_work_queue_lock);
-	}
-
-	/* sort out the race between module unloading and put_ref() */
-	slow_work_put_ref(work);
-	slow_work_done_thread_processing(id, work);
-
-	return true;
-
-auto_requeue:
-	/* we must complete the enqueue operation
-	 * - we transfer our ref on the item back to the appropriate queue
-	 * - don't wake another thread up as we're awake already
-	 */
-	slow_work_mark_time(work);
-	if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags))
-		list_add_tail(&work->link, &vslow_work_queue);
-	else
-		list_add_tail(&work->link, &slow_work_queue);
-	spin_unlock_irq(&slow_work_queue_lock);
-	slow_work_clear_thread_processing(id);
-	return true;
-}
-
-/**
- * slow_work_sleep_till_thread_needed - Sleep till thread needed by other work
- * work: The work item under execution that wants to sleep
- * _timeout: Scheduler sleep timeout
- *
- * Allow a requeueable work item to sleep on a slow-work processor thread until
- * that thread is needed to do some other work or the sleep is interrupted by
- * some other event.
- *
- * The caller must set up a wake up event before calling this and must have set
- * the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own
- * condition before calling this function as no test is made here.
- *
- * False is returned if there is nothing on the queue; true is returned if the
- * work item should be requeued
- */
-bool slow_work_sleep_till_thread_needed(struct slow_work *work,
-					signed long *_timeout)
-{
-	wait_queue_head_t *wfo_wq;
-	struct list_head *queue;
-
-	DEFINE_WAIT(wait);
-
-	if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) {
-		wfo_wq = &vslow_work_queue_waits_for_occupation;
-		queue = &vslow_work_queue;
-	} else {
-		wfo_wq = &slow_work_queue_waits_for_occupation;
-		queue = &slow_work_queue;
-	}
-
-	if (!list_empty(queue))
-		return true;
-
-	add_wait_queue_exclusive(wfo_wq, &wait);
-	if (list_empty(queue))
-		*_timeout = schedule_timeout(*_timeout);
-	finish_wait(wfo_wq, &wait);
-
-	return !list_empty(queue);
-}
-EXPORT_SYMBOL(slow_work_sleep_till_thread_needed);
-
-/**
- * slow_work_enqueue - Schedule a slow work item for processing
- * @work: The work item to queue
- *
- * Schedule a slow work item for processing.  If the item is already undergoing
- * execution, this guarantees not to re-enter the execution routine until the
- * first execution finishes.
- *
- * The item is pinned by this function as it retains a reference to it, managed
- * through the item operations.  The item is unpinned once it has been
- * executed.
- *
- * An item may hog the thread that is running it for a relatively large amount
- * of time, sufficient, for example, to perform several lookup, mkdir, create
- * and setxattr operations.  It may sleep on I/O and may sleep to obtain locks.
- *
- * Conversely, if a number of items are awaiting processing, it may take some
- * time before any given item is given attention.  The number of threads in the
- * pool may be increased to deal with demand, but only up to a limit.
- *
- * If SLOW_WORK_VERY_SLOW is set on the work item, then it will be placed in
- * the very slow queue, from which only a portion of the threads will be
- * allowed to pick items to execute.  This ensures that very slow items won't
- * overly block ones that are just ordinarily slow.
- *
- * Returns 0 if successful, -EAGAIN if not (or -ECANCELED if cancelled work is
- * attempted queued)
- */
-int slow_work_enqueue(struct slow_work *work)
-{
-	wait_queue_head_t *wfo_wq;
-	struct list_head *queue;
-	unsigned long flags;
-	int ret;
-
-	if (test_bit(SLOW_WORK_CANCELLING, &work->flags))
-		return -ECANCELED;
-
-	BUG_ON(slow_work_user_count <= 0);
-	BUG_ON(!work);
-	BUG_ON(!work->ops);
-
-	/* when honouring an enqueue request, we only promise that we will run
-	 * the work function in the future; we do not promise to run it once
-	 * per enqueue request
-	 *
-	 * we use the PENDING bit to merge together repeat requests without
-	 * having to disable IRQs and take the spinlock, whilst still
-	 * maintaining our promise
-	 */
-	if (!test_and_set_bit_lock(SLOW_WORK_PENDING, &work->flags)) {
-		if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) {
-			wfo_wq = &vslow_work_queue_waits_for_occupation;
-			queue = &vslow_work_queue;
-		} else {
-			wfo_wq = &slow_work_queue_waits_for_occupation;
-			queue = &slow_work_queue;
-		}
-
-		spin_lock_irqsave(&slow_work_queue_lock, flags);
-
-		if (unlikely(test_bit(SLOW_WORK_CANCELLING, &work->flags)))
-			goto cancelled;
-
-		/* we promise that we will not attempt to execute the work
-		 * function in more than one thread simultaneously
-		 *
-		 * this, however, leaves us with a problem if we're asked to
-		 * enqueue the work whilst someone is executing the work
-		 * function as simply queueing the work immediately means that
-		 * another thread may try executing it whilst it is already
-		 * under execution
-		 *
-		 * to deal with this, we set the ENQ_DEFERRED bit instead of
-		 * enqueueing, and the thread currently executing the work
-		 * function will enqueue the work item when the work function
-		 * returns and it has cleared the EXECUTING bit
-		 */
-		if (test_bit(SLOW_WORK_EXECUTING, &work->flags)) {
-			set_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags);
-		} else {
-			ret = slow_work_get_ref(work);
-			if (ret < 0)
-				goto failed;
-			slow_work_mark_time(work);
-			list_add_tail(&work->link, queue);
-			wake_up(&slow_work_thread_wq);
-
-			/* if someone who could be requeued is sleeping on a
-			 * thread, then ask them to yield their thread */
-			if (work->link.prev == queue)
-				wake_up(wfo_wq);
-		}
-
-		spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	}
-	return 0;
-
-cancelled:
-	ret = -ECANCELED;
-failed:
-	spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	return ret;
-}
-EXPORT_SYMBOL(slow_work_enqueue);
-
-static int slow_work_wait(void *word)
-{
-	schedule();
-	return 0;
-}
-
-/**
- * slow_work_cancel - Cancel a slow work item
- * @work: The work item to cancel
- *
- * This function will cancel a previously enqueued work item. If we cannot
- * cancel the work item, it is guarenteed to have run when this function
- * returns.
- */
-void slow_work_cancel(struct slow_work *work)
-{
-	bool wait = true, put = false;
-
-	set_bit(SLOW_WORK_CANCELLING, &work->flags);
-	smp_mb();
-
-	/* if the work item is a delayed work item with an active timer, we
-	 * need to wait for the timer to finish _before_ getting the spinlock,
-	 * lest we deadlock against the timer routine
-	 *
-	 * the timer routine will leave DELAYED set if it notices the
-	 * CANCELLING flag in time
-	 */
-	if (test_bit(SLOW_WORK_DELAYED, &work->flags)) {
-		struct delayed_slow_work *dwork =
-			container_of(work, struct delayed_slow_work, work);
-		del_timer_sync(&dwork->timer);
-	}
-
-	spin_lock_irq(&slow_work_queue_lock);
-
-	if (test_bit(SLOW_WORK_DELAYED, &work->flags)) {
-		/* the timer routine aborted or never happened, so we are left
-		 * holding the timer's reference on the item and should just
-		 * drop the pending flag and wait for any ongoing execution to
-		 * finish */
-		struct delayed_slow_work *dwork =
-			container_of(work, struct delayed_slow_work, work);
-
-		BUG_ON(timer_pending(&dwork->timer));
-		BUG_ON(!list_empty(&work->link));
-
-		clear_bit(SLOW_WORK_DELAYED, &work->flags);
-		put = true;
-		clear_bit(SLOW_WORK_PENDING, &work->flags);
-
-	} else if (test_bit(SLOW_WORK_PENDING, &work->flags) &&
-		   !list_empty(&work->link)) {
-		/* the link in the pending queue holds a reference on the item
-		 * that we will need to release */
-		list_del_init(&work->link);
-		wait = false;
-		put = true;
-		clear_bit(SLOW_WORK_PENDING, &work->flags);
-
-	} else if (test_and_clear_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags)) {
-		/* the executor is holding our only reference on the item, so
-		 * we merely need to wait for it to finish executing */
-		clear_bit(SLOW_WORK_PENDING, &work->flags);
-	}
-
-	spin_unlock_irq(&slow_work_queue_lock);
-
-	/* the EXECUTING flag is set by the executor whilst the spinlock is set
-	 * and before the item is dequeued - so assuming the above doesn't
-	 * actually dequeue it, simply waiting for the EXECUTING flag to be
-	 * released here should be sufficient */
-	if (wait)
-		wait_on_bit(&work->flags, SLOW_WORK_EXECUTING, slow_work_wait,
-			    TASK_UNINTERRUPTIBLE);
-
-	clear_bit(SLOW_WORK_CANCELLING, &work->flags);
-	if (put)
-		slow_work_put_ref(work);
-}
-EXPORT_SYMBOL(slow_work_cancel);
-
-/*
- * Handle expiry of the delay timer, indicating that a delayed slow work item
- * should now be queued if not cancelled
- */
-static void delayed_slow_work_timer(unsigned long data)
-{
-	wait_queue_head_t *wfo_wq;
-	struct list_head *queue;
-	struct slow_work *work = (struct slow_work *) data;
-	unsigned long flags;
-	bool queued = false, put = false, first = false;
-
-	if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) {
-		wfo_wq = &vslow_work_queue_waits_for_occupation;
-		queue = &vslow_work_queue;
-	} else {
-		wfo_wq = &slow_work_queue_waits_for_occupation;
-		queue = &slow_work_queue;
-	}
-
-	spin_lock_irqsave(&slow_work_queue_lock, flags);
-	if (likely(!test_bit(SLOW_WORK_CANCELLING, &work->flags))) {
-		clear_bit(SLOW_WORK_DELAYED, &work->flags);
-
-		if (test_bit(SLOW_WORK_EXECUTING, &work->flags)) {
-			/* we discard the reference the timer was holding in
-			 * favour of the one the executor holds */
-			set_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags);
-			put = true;
-		} else {
-			slow_work_mark_time(work);
-			list_add_tail(&work->link, queue);
-			queued = true;
-			if (work->link.prev == queue)
-				first = true;
-		}
-	}
-
-	spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	if (put)
-		slow_work_put_ref(work);
-	if (first)
-		wake_up(wfo_wq);
-	if (queued)
-		wake_up(&slow_work_thread_wq);
-}
-
-/**
- * delayed_slow_work_enqueue - Schedule a delayed slow work item for processing
- * @dwork: The delayed work item to queue
- * @delay: When to start executing the work, in jiffies from now
- *
- * This is similar to slow_work_enqueue(), but it adds a delay before the work
- * is actually queued for processing.
- *
- * The item can have delayed processing requested on it whilst it is being
- * executed.  The delay will begin immediately, and if it expires before the
- * item finishes executing, the item will be placed back on the queue when it
- * has done executing.
- */
-int delayed_slow_work_enqueue(struct delayed_slow_work *dwork,
-			      unsigned long delay)
-{
-	struct slow_work *work = &dwork->work;
-	unsigned long flags;
-	int ret;
-
-	if (delay == 0)
-		return slow_work_enqueue(&dwork->work);
-
-	BUG_ON(slow_work_user_count <= 0);
-	BUG_ON(!work);
-	BUG_ON(!work->ops);
-
-	if (test_bit(SLOW_WORK_CANCELLING, &work->flags))
-		return -ECANCELED;
-
-	if (!test_and_set_bit_lock(SLOW_WORK_PENDING, &work->flags)) {
-		spin_lock_irqsave(&slow_work_queue_lock, flags);
-
-		if (test_bit(SLOW_WORK_CANCELLING, &work->flags))
-			goto cancelled;
-
-		/* the timer holds a reference whilst it is pending */
-		ret = slow_work_get_ref(work);
-		if (ret < 0)
-			goto cant_get_ref;
-
-		if (test_and_set_bit(SLOW_WORK_DELAYED, &work->flags))
-			BUG();
-		dwork->timer.expires = jiffies + delay;
-		dwork->timer.data = (unsigned long) work;
-		dwork->timer.function = delayed_slow_work_timer;
-		add_timer(&dwork->timer);
-
-		spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	}
-
-	return 0;
-
-cancelled:
-	ret = -ECANCELED;
-cant_get_ref:
-	spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	return ret;
-}
-EXPORT_SYMBOL(delayed_slow_work_enqueue);
-
-/*
- * Schedule a cull of the thread pool at some time in the near future
- */
-static void slow_work_schedule_cull(void)
-{
-	mod_timer(&slow_work_cull_timer,
-		  round_jiffies(jiffies + SLOW_WORK_CULL_TIMEOUT));
-}
-
-/*
- * Worker thread culling algorithm
- */
-static bool slow_work_cull_thread(void)
-{
-	unsigned long flags;
-	bool do_cull = false;
-
-	spin_lock_irqsave(&slow_work_queue_lock, flags);
-
-	if (slow_work_cull) {
-		slow_work_cull = false;
-
-		if (list_empty(&slow_work_queue) &&
-		    list_empty(&vslow_work_queue) &&
-		    atomic_read(&slow_work_thread_count) >
-		    slow_work_min_threads) {
-			slow_work_schedule_cull();
-			do_cull = true;
-		}
-	}
-
-	spin_unlock_irqrestore(&slow_work_queue_lock, flags);
-	return do_cull;
-}
-
-/*
- * Determine if there is slow work available for dispatch
- */
-static inline bool slow_work_available(int vsmax)
-{
-	return !list_empty(&slow_work_queue) ||
-		(!list_empty(&vslow_work_queue) &&
-		 atomic_read(&vslow_work_executing_count) < vsmax);
-}
-
-/*
- * Worker thread dispatcher
- */
-static int slow_work_thread(void *_data)
-{
-	int vsmax, id;
-
-	DEFINE_WAIT(wait);
-
-	set_freezable();
-	set_user_nice(current, -5);
-
-	/* allocate ourselves an ID */
-	spin_lock_irq(&slow_work_queue_lock);
-	id = find_first_zero_bit(slow_work_ids, SLOW_WORK_THREAD_LIMIT);
-	BUG_ON(id < 0 || id >= SLOW_WORK_THREAD_LIMIT);
-	__set_bit(id, slow_work_ids);
-	slow_work_set_thread_pid(id, current->pid);
-	spin_unlock_irq(&slow_work_queue_lock);
-
-	sprintf(current->comm, "kslowd%03u", id);
-
-	for (;;) {
-		vsmax = vslow_work_proportion;
-		vsmax *= atomic_read(&slow_work_thread_count);
-		vsmax /= 100;
-
-		prepare_to_wait_exclusive(&slow_work_thread_wq, &wait,
-					  TASK_INTERRUPTIBLE);
-		if (!freezing(current) &&
-		    !slow_work_threads_should_exit &&
-		    !slow_work_available(vsmax) &&
-		    !slow_work_cull)
-			schedule();
-		finish_wait(&slow_work_thread_wq, &wait);
-
-		try_to_freeze();
-
-		vsmax = vslow_work_proportion;
-		vsmax *= atomic_read(&slow_work_thread_count);
-		vsmax /= 100;
-
-		if (slow_work_available(vsmax) && slow_work_execute(id)) {
-			cond_resched();
-			if (list_empty(&slow_work_queue) &&
-			    list_empty(&vslow_work_queue) &&
-			    atomic_read(&slow_work_thread_count) >
-			    slow_work_min_threads)
-				slow_work_schedule_cull();
-			continue;
-		}
-
-		if (slow_work_threads_should_exit)
-			break;
-
-		if (slow_work_cull && slow_work_cull_thread())
-			break;
-	}
-
-	spin_lock_irq(&slow_work_queue_lock);
-	slow_work_set_thread_pid(id, 0);
-	__clear_bit(id, slow_work_ids);
-	spin_unlock_irq(&slow_work_queue_lock);
-
-	if (atomic_dec_and_test(&slow_work_thread_count))
-		complete_and_exit(&slow_work_last_thread_exited, 0);
-	return 0;
-}
-
-/*
- * Handle thread cull timer expiration
- */
-static void slow_work_cull_timeout(unsigned long data)
-{
-	slow_work_cull = true;
-	wake_up(&slow_work_thread_wq);
-}
-
-/*
- * Start a new slow work thread
- */
-static void slow_work_new_thread_execute(struct slow_work *work)
-{
-	struct task_struct *p;
-
-	if (slow_work_threads_should_exit)
-		return;
-
-	if (atomic_read(&slow_work_thread_count) >= slow_work_max_threads)
-		return;
-
-	if (!mutex_trylock(&slow_work_user_lock))
-		return;
-
-	slow_work_may_not_start_new_thread = true;
-	atomic_inc(&slow_work_thread_count);
-	p = kthread_run(slow_work_thread, NULL, "kslowd");
-	if (IS_ERR(p)) {
-		printk(KERN_DEBUG "Slow work thread pool: OOM\n");
-		if (atomic_dec_and_test(&slow_work_thread_count))
-			BUG(); /* we're running on a slow work thread... */
-		mod_timer(&slow_work_oom_timer,
-			  round_jiffies(jiffies + SLOW_WORK_OOM_TIMEOUT));
-	} else {
-		/* ratelimit the starting of new threads */
-		mod_timer(&slow_work_oom_timer, jiffies + 1);
-	}
-
-	mutex_unlock(&slow_work_user_lock);
-}
-
-static const struct slow_work_ops slow_work_new_thread_ops = {
-	.owner		= THIS_MODULE,
-	.execute	= slow_work_new_thread_execute,
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	.desc		= slow_work_new_thread_desc,
-#endif
-};
-
-/*
- * post-OOM new thread start suppression expiration
- */
-static void slow_work_oom_timeout(unsigned long data)
-{
-	slow_work_may_not_start_new_thread = false;
-}
-
-#ifdef CONFIG_SYSCTL
-/*
- * Handle adjustment of the minimum number of threads
- */
-static int slow_work_min_threads_sysctl(struct ctl_table *table, int write,
-					void __user *buffer,
-					size_t *lenp, loff_t *ppos)
-{
-	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	int n;
-
-	if (ret == 0) {
-		mutex_lock(&slow_work_user_lock);
-		if (slow_work_user_count > 0) {
-			/* see if we need to start or stop threads */
-			n = atomic_read(&slow_work_thread_count) -
-				slow_work_min_threads;
-
-			if (n < 0 && !slow_work_may_not_start_new_thread)
-				slow_work_enqueue(&slow_work_new_thread);
-			else if (n > 0)
-				slow_work_schedule_cull();
-		}
-		mutex_unlock(&slow_work_user_lock);
-	}
-
-	return ret;
-}
-
-/*
- * Handle adjustment of the maximum number of threads
- */
-static int slow_work_max_threads_sysctl(struct ctl_table *table, int write,
-					void __user *buffer,
-					size_t *lenp, loff_t *ppos)
-{
-	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	int n;
-
-	if (ret == 0) {
-		mutex_lock(&slow_work_user_lock);
-		if (slow_work_user_count > 0) {
-			/* see if we need to stop threads */
-			n = slow_work_max_threads -
-				atomic_read(&slow_work_thread_count);
-
-			if (n < 0)
-				slow_work_schedule_cull();
-		}
-		mutex_unlock(&slow_work_user_lock);
-	}
-
-	return ret;
-}
-#endif /* CONFIG_SYSCTL */
-
-/**
- * slow_work_register_user - Register a user of the facility
- * @module: The module about to make use of the facility
- *
- * Register a user of the facility, starting up the initial threads if there
- * aren't any other users at this point.  This will return 0 if successful, or
- * an error if not.
- */
-int slow_work_register_user(struct module *module)
-{
-	struct task_struct *p;
-	int loop;
-
-	mutex_lock(&slow_work_user_lock);
-
-	if (slow_work_user_count == 0) {
-		printk(KERN_NOTICE "Slow work thread pool: Starting up\n");
-		init_completion(&slow_work_last_thread_exited);
-
-		slow_work_threads_should_exit = false;
-		slow_work_init(&slow_work_new_thread,
-			       &slow_work_new_thread_ops);
-		slow_work_may_not_start_new_thread = false;
-		slow_work_cull = false;
-
-		/* start the minimum number of threads */
-		for (loop = 0; loop < slow_work_min_threads; loop++) {
-			atomic_inc(&slow_work_thread_count);
-			p = kthread_run(slow_work_thread, NULL, "kslowd");
-			if (IS_ERR(p))
-				goto error;
-		}
-		printk(KERN_NOTICE "Slow work thread pool: Ready\n");
-	}
-
-	slow_work_user_count++;
-	mutex_unlock(&slow_work_user_lock);
-	return 0;
-
-error:
-	if (atomic_dec_and_test(&slow_work_thread_count))
-		complete(&slow_work_last_thread_exited);
-	if (loop > 0) {
-		printk(KERN_ERR "Slow work thread pool:"
-		       " Aborting startup on ENOMEM\n");
-		slow_work_threads_should_exit = true;
-		wake_up_all(&slow_work_thread_wq);
-		wait_for_completion(&slow_work_last_thread_exited);
-		printk(KERN_ERR "Slow work thread pool: Aborted\n");
-	}
-	mutex_unlock(&slow_work_user_lock);
-	return PTR_ERR(p);
-}
-EXPORT_SYMBOL(slow_work_register_user);
-
-/*
- * wait for all outstanding items from the calling module to complete
- * - note that more items may be queued whilst we're waiting
- */
-static void slow_work_wait_for_items(struct module *module)
-{
-#ifdef CONFIG_MODULES
-	DECLARE_WAITQUEUE(myself, current);
-	struct slow_work *work;
-	int loop;
-
-	mutex_lock(&slow_work_unreg_sync_lock);
-	add_wait_queue(&slow_work_unreg_wq, &myself);
-
-	for (;;) {
-		spin_lock_irq(&slow_work_queue_lock);
-
-		/* first of all, we wait for the last queued item in each list
-		 * to be processed */
-		list_for_each_entry_reverse(work, &vslow_work_queue, link) {
-			if (work->owner == module) {
-				set_current_state(TASK_UNINTERRUPTIBLE);
-				slow_work_unreg_work_item = work;
-				goto do_wait;
-			}
-		}
-		list_for_each_entry_reverse(work, &slow_work_queue, link) {
-			if (work->owner == module) {
-				set_current_state(TASK_UNINTERRUPTIBLE);
-				slow_work_unreg_work_item = work;
-				goto do_wait;
-			}
-		}
-
-		/* then we wait for the items being processed to finish */
-		slow_work_unreg_module = module;
-		smp_mb();
-		for (loop = 0; loop < SLOW_WORK_THREAD_LIMIT; loop++) {
-			if (slow_work_thread_processing[loop] == module)
-				goto do_wait;
-		}
-		spin_unlock_irq(&slow_work_queue_lock);
-		break; /* okay, we're done */
-
-	do_wait:
-		spin_unlock_irq(&slow_work_queue_lock);
-		schedule();
-		slow_work_unreg_work_item = NULL;
-		slow_work_unreg_module = NULL;
-	}
-
-	remove_wait_queue(&slow_work_unreg_wq, &myself);
-	mutex_unlock(&slow_work_unreg_sync_lock);
-#endif /* CONFIG_MODULES */
-}
-
-/**
- * slow_work_unregister_user - Unregister a user of the facility
- * @module: The module whose items should be cleared
- *
- * Unregister a user of the facility, killing all the threads if this was the
- * last one.
- *
- * This waits for all the work items belonging to the nominated module to go
- * away before proceeding.
- */
-void slow_work_unregister_user(struct module *module)
-{
-	/* first of all, wait for all outstanding items from the calling module
-	 * to complete */
-	if (module)
-		slow_work_wait_for_items(module);
-
-	/* then we can actually go about shutting down the facility if need
-	 * be */
-	mutex_lock(&slow_work_user_lock);
-
-	BUG_ON(slow_work_user_count <= 0);
-
-	slow_work_user_count--;
-	if (slow_work_user_count == 0) {
-		printk(KERN_NOTICE "Slow work thread pool: Shutting down\n");
-		slow_work_threads_should_exit = true;
-		del_timer_sync(&slow_work_cull_timer);
-		del_timer_sync(&slow_work_oom_timer);
-		wake_up_all(&slow_work_thread_wq);
-		wait_for_completion(&slow_work_last_thread_exited);
-		printk(KERN_NOTICE "Slow work thread pool:"
-		       " Shut down complete\n");
-	}
-
-	mutex_unlock(&slow_work_user_lock);
-}
-EXPORT_SYMBOL(slow_work_unregister_user);
-
-/*
- * Initialise the slow work facility
- */
-static int __init init_slow_work(void)
-{
-	unsigned nr_cpus = num_possible_cpus();
-
-	if (slow_work_max_threads < nr_cpus)
-		slow_work_max_threads = nr_cpus;
-#ifdef CONFIG_SYSCTL
-	if (slow_work_max_max_threads < nr_cpus * 2)
-		slow_work_max_max_threads = nr_cpus * 2;
-#endif
-#ifdef CONFIG_SLOW_WORK_DEBUG
-	{
-		struct dentry *dbdir;
-
-		dbdir = debugfs_create_dir("slow_work", NULL);
-		if (dbdir && !IS_ERR(dbdir))
-			debugfs_create_file("runqueue", S_IFREG | 0400, dbdir,
-					    NULL, &slow_work_runqueue_fops);
-	}
-#endif
-	return 0;
-}
-
-subsys_initcall(init_slow_work);