#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/wait.h>
-
-#define SLOW_WORK_CULL_TIMEOUT (5 * HZ) /* cull threads 5s after running out of
- * things to do */
-#define SLOW_WORK_OOM_TIMEOUT (5 * HZ) /* can't start new threads for 5s after
- * OOM */
+#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, struct file *,
+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 , struct file *,
+static int slow_work_max_threads_sysctl(struct ctl_table *, int ,
void __user *, size_t *, loff_t *);
#endif
#ifdef CONFIG_SYSCTL
static const int slow_work_min_min_threads = 2;
-static int slow_work_max_max_threads = 255;
+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[] = {
{
- .ctl_name = CTL_UNNUMBERED,
.procname = "min-threads",
.data = &slow_work_min_threads,
.maxlen = sizeof(unsigned),
.extra2 = &slow_work_max_threads,
},
{
- .ctl_name = CTL_UNNUMBERED,
.procname = "max-threads",
.data = &slow_work_max_threads,
.maxlen = sizeof(unsigned),
.extra2 = (void *) &slow_work_max_max_threads,
},
{
- .ctl_name = CTL_UNNUMBERED,
.procname = "vslow-percentage",
.data = &vslow_work_proportion,
.maxlen = sizeof(unsigned),
.mode = 0644,
- .proc_handler = &proc_dointvec_minmax,
+ .proc_handler = proc_dointvec_minmax,
.extra1 = (void *) &slow_work_min_vslow,
.extra2 = (void *) &slow_work_max_vslow,
},
- { .ctl_name = 0 }
+ {}
};
#endif
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.
*/
-static LIST_HEAD(slow_work_queue);
-static LIST_HEAD(vslow_work_queue);
-static DEFINE_SPINLOCK(slow_work_queue_lock);
+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
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.
* Attempt to execute stuff queued on a slow thread. Return true if we managed
* it, false if there was nothing to do.
*/
-static bool slow_work_execute(void)
+static noinline bool slow_work_execute(int id)
{
struct slow_work *work = NULL;
unsigned vsmax;
} 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)
if (!test_and_clear_bit(SLOW_WORK_PENDING, &work->flags))
BUG();
- work->ops->execute(work);
+ /* 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
spin_unlock_irq(&slow_work_queue_lock);
}
- work->ops->put_ref(work);
+ /* 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 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
*
* 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.
+ * 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);
- BUG_ON(!work->ops->get_ref);
/* 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
* 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
*
if (test_bit(SLOW_WORK_EXECUTING, &work->flags)) {
set_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags);
} else {
- if (work->ops->get_ref(work) < 0)
- goto cant_get_ref;
- 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);
+ 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;
-cant_get_ref:
+cancelled:
+ ret = -ECANCELED;
+failed:
spin_unlock_irqrestore(&slow_work_queue_lock, flags);
- return -EAGAIN;
+ 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
*/
list_empty(&vslow_work_queue) &&
atomic_read(&slow_work_thread_count) >
slow_work_min_threads) {
- mod_timer(&slow_work_cull_timer,
- jiffies + SLOW_WORK_CULL_TIMEOUT);
+ slow_work_schedule_cull();
do_cull = true;
}
}
*/
static int slow_work_thread(void *_data)
{
- int vsmax;
+ 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(&slow_work_thread_wq, &wait,
- TASK_INTERRUPTIBLE);
+ prepare_to_wait_exclusive(&slow_work_thread_wq, &wait,
+ TASK_INTERRUPTIBLE);
if (!freezing(current) &&
!slow_work_threads_should_exit &&
!slow_work_available(vsmax) &&
vsmax *= atomic_read(&slow_work_thread_count);
vsmax /= 100;
- if (slow_work_available(vsmax) && slow_work_execute()) {
+ 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)
- mod_timer(&slow_work_cull_timer,
- jiffies + SLOW_WORK_CULL_TIMEOUT);
+ slow_work_schedule_cull();
continue;
}
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;
}
/*
- * Get a reference on slow work thread starter
- */
-static int slow_work_new_thread_get_ref(struct slow_work *work)
-{
- return 0;
-}
-
-/*
- * Drop a reference on slow work thread starter
- */
-static void slow_work_new_thread_put_ref(struct slow_work *work)
-{
-}
-
-/*
* Start a new slow work thread
*/
static void slow_work_new_thread_execute(struct slow_work *work)
if (atomic_dec_and_test(&slow_work_thread_count))
BUG(); /* we're running on a slow work thread... */
mod_timer(&slow_work_oom_timer,
- jiffies + SLOW_WORK_OOM_TIMEOUT);
+ round_jiffies(jiffies + SLOW_WORK_OOM_TIMEOUT));
} else {
/* ratelimit the starting of new threads */
mod_timer(&slow_work_oom_timer, jiffies + 1);
}
static const struct slow_work_ops slow_work_new_thread_ops = {
- .get_ref = slow_work_new_thread_get_ref,
- .put_ref = slow_work_new_thread_put_ref,
+ .owner = THIS_MODULE,
.execute = slow_work_new_thread_execute,
+#ifdef CONFIG_SLOW_WORK_DEBUG
+ .desc = slow_work_new_thread_desc,
+#endif
};
/*
* Handle adjustment of the minimum number of threads
*/
static int slow_work_min_threads_sysctl(struct ctl_table *table, int write,
- struct file *filp, void __user *buffer,
+ void __user *buffer,
size_t *lenp, loff_t *ppos)
{
- int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
+ int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
int n;
if (ret == 0) {
if (n < 0 && !slow_work_may_not_start_new_thread)
slow_work_enqueue(&slow_work_new_thread);
else if (n > 0)
- mod_timer(&slow_work_cull_timer,
- jiffies + SLOW_WORK_CULL_TIMEOUT);
+ slow_work_schedule_cull();
}
mutex_unlock(&slow_work_user_lock);
}
* Handle adjustment of the maximum number of threads
*/
static int slow_work_max_threads_sysctl(struct ctl_table *table, int write,
- struct file *filp, void __user *buffer,
+ void __user *buffer,
size_t *lenp, loff_t *ppos)
{
- int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
+ int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
int n;
if (ret == 0) {
atomic_read(&slow_work_thread_count);
if (n < 0)
- mod_timer(&slow_work_cull_timer,
- jiffies + SLOW_WORK_CULL_TIMEOUT);
+ slow_work_schedule_cull();
}
mutex_unlock(&slow_work_user_lock);
}
/**
* 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(void)
+int slow_work_register_user(struct module *module)
{
struct task_struct *p;
int loop;
}
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(void)
+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);
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;
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff