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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel…
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…/git/tj/wq

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: use zalloc_cpumask_var() for gcwq->mayday_mask
  workqueue: fix GCWQ_DISASSOCIATED initialization
  workqueue: Add a workqueue chapter to the tracepoint docbook
  workqueue: fix cwq->nr_active underflow
  workqueue: improve destroy_workqueue() debuggability
  workqueue: mark lock acquisition on worker_maybe_bind_and_lock()
  workqueue: annotate lock context change
  workqueue: free rescuer on destroy_workqueue
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@torvalds
torvalds committed Sep 7, 2010
2 parents 608307e + 9c37547 commit cd4d4fc
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Showing 3 changed files with 54 additions and 22 deletions.
5 changes: 5 additions & 0 deletions Documentation/DocBook/tracepoint.tmpl
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Original file line number Diff line number Diff line change
Expand Up @@ -104,4 +104,9 @@
<title>Block IO</title>
!Iinclude/trace/events/block.h
</chapter>

<chapter id="workqueue">
<title>Workqueue</title>
!Iinclude/trace/events/workqueue.h
</chapter>
</book>
18 changes: 11 additions & 7 deletions include/linux/workqueue.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,18 +25,20 @@ typedef void (*work_func_t)(struct work_struct *work);

enum {
WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */
WORK_STRUCT_CWQ_BIT = 1, /* data points to cwq */
WORK_STRUCT_LINKED_BIT = 2, /* next work is linked to this one */
WORK_STRUCT_DELAYED_BIT = 1, /* work item is delayed */
WORK_STRUCT_CWQ_BIT = 2, /* data points to cwq */
WORK_STRUCT_LINKED_BIT = 3, /* next work is linked to this one */
#ifdef CONFIG_DEBUG_OBJECTS_WORK
WORK_STRUCT_STATIC_BIT = 3, /* static initializer (debugobjects) */
WORK_STRUCT_COLOR_SHIFT = 4, /* color for workqueue flushing */
WORK_STRUCT_STATIC_BIT = 4, /* static initializer (debugobjects) */
WORK_STRUCT_COLOR_SHIFT = 5, /* color for workqueue flushing */
#else
WORK_STRUCT_COLOR_SHIFT = 3, /* color for workqueue flushing */
WORK_STRUCT_COLOR_SHIFT = 4, /* color for workqueue flushing */
#endif

WORK_STRUCT_COLOR_BITS = 4,

WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
WORK_STRUCT_DELAYED = 1 << WORK_STRUCT_DELAYED_BIT,
WORK_STRUCT_CWQ = 1 << WORK_STRUCT_CWQ_BIT,
WORK_STRUCT_LINKED = 1 << WORK_STRUCT_LINKED_BIT,
#ifdef CONFIG_DEBUG_OBJECTS_WORK
Expand All @@ -59,8 +61,8 @@ enum {

/*
* Reserve 7 bits off of cwq pointer w/ debugobjects turned
* off. This makes cwqs aligned to 128 bytes which isn't too
* excessive while allowing 15 workqueue flush colors.
* off. This makes cwqs aligned to 256 bytes and allows 15
* workqueue flush colors.
*/
WORK_STRUCT_FLAG_BITS = WORK_STRUCT_COLOR_SHIFT +
WORK_STRUCT_COLOR_BITS,
Expand Down Expand Up @@ -241,6 +243,8 @@ enum {
WQ_HIGHPRI = 1 << 4, /* high priority */
WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */

WQ_DYING = 1 << 6, /* internal: workqueue is dying */

WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */
WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
WQ_DFL_ACTIVE = WQ_MAX_ACTIVE / 2,
Expand Down
53 changes: 38 additions & 15 deletions kernel/workqueue.c
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Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,8 @@ enum {
/*
* Structure fields follow one of the following exclusion rules.
*
* I: Set during initialization and read-only afterwards.
* I: Modifiable by initialization/destruction paths and read-only for
* everyone else.
*
* P: Preemption protected. Disabling preemption is enough and should
* only be modified and accessed from the local cpu.
Expand Down Expand Up @@ -198,7 +199,7 @@ typedef cpumask_var_t mayday_mask_t;
cpumask_test_and_set_cpu((cpu), (mask))
#define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
#define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
#define alloc_mayday_mask(maskp, gfp) alloc_cpumask_var((maskp), (gfp))
#define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp))
#define free_mayday_mask(mask) free_cpumask_var((mask))
#else
typedef unsigned long mayday_mask_t;
Expand Down Expand Up @@ -943,10 +944,14 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
struct global_cwq *gcwq;
struct cpu_workqueue_struct *cwq;
struct list_head *worklist;
unsigned int work_flags;
unsigned long flags;

debug_work_activate(work);

if (WARN_ON_ONCE(wq->flags & WQ_DYING))
return;

/* determine gcwq to use */
if (!(wq->flags & WQ_UNBOUND)) {
struct global_cwq *last_gcwq;
Expand Down Expand Up @@ -989,14 +994,17 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
BUG_ON(!list_empty(&work->entry));

cwq->nr_in_flight[cwq->work_color]++;
work_flags = work_color_to_flags(cwq->work_color);

if (likely(cwq->nr_active < cwq->max_active)) {
cwq->nr_active++;
worklist = gcwq_determine_ins_pos(gcwq, cwq);
} else
} else {
work_flags |= WORK_STRUCT_DELAYED;
worklist = &cwq->delayed_works;
}

insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color));
insert_work(cwq, work, worklist, work_flags);

spin_unlock_irqrestore(&gcwq->lock, flags);
}
Expand Down Expand Up @@ -1215,6 +1223,7 @@ static void worker_leave_idle(struct worker *worker)
* bound), %false if offline.
*/
static bool worker_maybe_bind_and_lock(struct worker *worker)
__acquires(&gcwq->lock)
{
struct global_cwq *gcwq = worker->gcwq;
struct task_struct *task = worker->task;
Expand Down Expand Up @@ -1488,6 +1497,8 @@ static void gcwq_mayday_timeout(unsigned long __gcwq)
* otherwise.
*/
static bool maybe_create_worker(struct global_cwq *gcwq)
__releases(&gcwq->lock)
__acquires(&gcwq->lock)
{
if (!need_to_create_worker(gcwq))
return false;
Expand Down Expand Up @@ -1662,33 +1673,38 @@ static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);

move_linked_works(work, pos, NULL);
__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
cwq->nr_active++;
}

/**
* cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
* @cwq: cwq of interest
* @color: color of work which left the queue
* @delayed: for a delayed work
*
* A work either has completed or is removed from pending queue,
* decrement nr_in_flight of its cwq and handle workqueue flushing.
*
* CONTEXT:
* spin_lock_irq(gcwq->lock).
*/
static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
bool delayed)
{
/* ignore uncolored works */
if (color == WORK_NO_COLOR)
return;

cwq->nr_in_flight[color]--;
cwq->nr_active--;

if (!list_empty(&cwq->delayed_works)) {
/* one down, submit a delayed one */
if (cwq->nr_active < cwq->max_active)
cwq_activate_first_delayed(cwq);
if (!delayed) {
cwq->nr_active--;
if (!list_empty(&cwq->delayed_works)) {
/* one down, submit a delayed one */
if (cwq->nr_active < cwq->max_active)
cwq_activate_first_delayed(cwq);
}
}

/* is flush in progress and are we at the flushing tip? */
Expand Down Expand Up @@ -1725,6 +1741,8 @@ static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
* spin_lock_irq(gcwq->lock) which is released and regrabbed.
*/
static void process_one_work(struct worker *worker, struct work_struct *work)
__releases(&gcwq->lock)
__acquires(&gcwq->lock)
{
struct cpu_workqueue_struct *cwq = get_work_cwq(work);
struct global_cwq *gcwq = cwq->gcwq;
Expand Down Expand Up @@ -1823,7 +1841,7 @@ static void process_one_work(struct worker *worker, struct work_struct *work)
hlist_del_init(&worker->hentry);
worker->current_work = NULL;
worker->current_cwq = NULL;
cwq_dec_nr_in_flight(cwq, work_color);
cwq_dec_nr_in_flight(cwq, work_color, false);
}

/**
Expand Down Expand Up @@ -2388,7 +2406,8 @@ static int try_to_grab_pending(struct work_struct *work)
debug_work_deactivate(work);
list_del_init(&work->entry);
cwq_dec_nr_in_flight(get_work_cwq(work),
get_work_color(work));
get_work_color(work),
*work_data_bits(work) & WORK_STRUCT_DELAYED);
ret = 1;
}
}
Expand Down Expand Up @@ -2791,7 +2810,6 @@ struct workqueue_struct *__alloc_workqueue_key(const char *name,
if (IS_ERR(rescuer->task))
goto err;

wq->rescuer = rescuer;
rescuer->task->flags |= PF_THREAD_BOUND;
wake_up_process(rescuer->task);
}
Expand Down Expand Up @@ -2833,6 +2851,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
{
unsigned int cpu;

wq->flags |= WQ_DYING;
flush_workqueue(wq);

/*
Expand All @@ -2857,6 +2876,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
if (wq->flags & WQ_RESCUER) {
kthread_stop(wq->rescuer->task);
free_mayday_mask(wq->mayday_mask);
kfree(wq->rescuer);
}

free_cwqs(wq);
Expand Down Expand Up @@ -3239,6 +3259,8 @@ static int __cpuinit trustee_thread(void *__gcwq)
* multiple times. To be used by cpu_callback.
*/
static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state)
__releases(&gcwq->lock)
__acquires(&gcwq->lock)
{
if (!(gcwq->trustee_state == state ||
gcwq->trustee_state == TRUSTEE_DONE)) {
Expand Down Expand Up @@ -3545,8 +3567,7 @@ static int __init init_workqueues(void)
spin_lock_init(&gcwq->lock);
INIT_LIST_HEAD(&gcwq->worklist);
gcwq->cpu = cpu;
if (cpu == WORK_CPU_UNBOUND)
gcwq->flags |= GCWQ_DISASSOCIATED;
gcwq->flags |= GCWQ_DISASSOCIATED;

INIT_LIST_HEAD(&gcwq->idle_list);
for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
Expand All @@ -3570,6 +3591,8 @@ static int __init init_workqueues(void)
struct global_cwq *gcwq = get_gcwq(cpu);
struct worker *worker;

if (cpu != WORK_CPU_UNBOUND)
gcwq->flags &= ~GCWQ_DISASSOCIATED;
worker = create_worker(gcwq, true);
BUG_ON(!worker);
spin_lock_irq(&gcwq->lock);
Expand Down

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