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Next: 2.6.34: simple IOMMU API extension to check safe interrupt remapping
From: Tejun Heo on 2 Jul 2010 05:30
This patch implements unbound workqueue which can be specified with
WQ_UNBOUND flag on creation. An unbound workqueue has the following
properties.

* It uses a dedicated gcwq with a pseudo CPU number WORK_CPU_UNBOUND.
This gcwq is always online and disassociated.

* Workers are not bound to any CPU and not concurrency managed. Works
are dispatched to workers as soon as possible and the only applied
limitation is @max_active. IOW, all unbound workqeueues are
implicitly high priority.

Unbound workqueues can be used as simple execution context provider.
Contexts unbound to any cpu are served as soon as possible.

Signed-off-by: Tejun Heo <tj(a)kernel.org>
Cc: Arjan van de Ven <arjan(a)linux.intel.com>
Cc: David Howells <dhowells(a)redhat.com>
---
include/linux/workqueue.h | 15 +++-
kernel/workqueue.c | 218 +++++++++++++++++++++++++++++++++------------
2 files changed, 173 insertions(+), 60 deletions(-)

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 139069a..67ce734 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -51,7 +51,8 @@ enum {
WORK_NO_COLOR = WORK_NR_COLORS,

/* special cpu IDs */
- WORK_CPU_NONE = NR_CPUS,
+ WORK_CPU_UNBOUND = NR_CPUS,
+ WORK_CPU_NONE = NR_CPUS + 1,
WORK_CPU_LAST = WORK_CPU_NONE,

/*
@@ -237,11 +238,17 @@ enum {
WQ_RESCUER = 1 << 3, /* has an rescue worker */
WQ_HIGHPRI = 1 << 4, /* high priority */
WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */
+ WQ_UNBOUND = 1 << 6, /* not bound to any cpu */

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,
};

+/* unbound wq's aren't per-cpu, scale max_active according to #cpus */
+#define WQ_UNBOUND_MAX_ACTIVE \
+ max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
+
/*
* System-wide workqueues which are always present.
*
@@ -256,10 +263,16 @@ enum {
* system_nrt_wq is non-reentrant and guarantees that any given work
* item is never executed in parallel by multiple CPUs. Queue
* flushing might take relatively long.
+ *
+ * system_unbound_wq is unbound workqueue. Workers are not bound to
+ * any specific CPU, not concurrency managed, and all queued works are
+ * executed immediately as long as max_active limit is not reached and
+ * resources are available.
*/
extern struct workqueue_struct *system_wq;
extern struct workqueue_struct *system_long_wq;
extern struct workqueue_struct *system_nrt_wq;
+extern struct workqueue_struct *system_unbound_wq;

extern struct workqueue_struct *
__alloc_workqueue_key(const char *name, unsigned int flags, int max_active,
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index a105ddf..4608563 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -53,9 +53,10 @@ enum {
WORKER_ROGUE = 1 << 4, /* not bound to any cpu */
WORKER_REBIND = 1 << 5, /* mom is home, come back */
WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
+ WORKER_UNBOUND = 1 << 7, /* worker is unbound */

WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND |
- WORKER_CPU_INTENSIVE,
+ WORKER_CPU_INTENSIVE | WORKER_UNBOUND,

/* gcwq->trustee_state */
TRUSTEE_START = 0, /* start */
@@ -96,7 +97,7 @@ enum {
* X: During normal operation, modification requires gcwq->lock and
* should be done only from local cpu. Either disabling preemption
* on local cpu or grabbing gcwq->lock is enough for read access.
- * While trustee is in charge, it's identical to L.
+ * If GCWQ_DISASSOCIATED is set, it's identical to L.
*
* F: wq->flush_mutex protected.
*
@@ -220,14 +221,52 @@ struct workqueue_struct {
struct workqueue_struct *system_wq __read_mostly;
struct workqueue_struct *system_long_wq __read_mostly;
struct workqueue_struct *system_nrt_wq __read_mostly;
+struct workqueue_struct *system_unbound_wq __read_mostly;
EXPORT_SYMBOL_GPL(system_wq);
EXPORT_SYMBOL_GPL(system_long_wq);
EXPORT_SYMBOL_GPL(system_nrt_wq);
+EXPORT_SYMBOL_GPL(system_unbound_wq);

#define for_each_busy_worker(worker, i, pos, gcwq) \
for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)

+static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask,
+ unsigned int sw)
+{
+ if (cpu < nr_cpu_ids) {
+ if (sw & 1) {
+ cpu = cpumask_next(cpu, mask);
+ if (cpu < nr_cpu_ids)
+ return cpu;
+ }
+ if (sw & 2)
+ return WORK_CPU_UNBOUND;
+ }
+ return WORK_CPU_NONE;
+}
+
+static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
+ struct workqueue_struct *wq)
+{
+ return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
+}
+
+#define for_each_gcwq_cpu(cpu) \
+ for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
+ (cpu) < WORK_CPU_NONE; \
+ (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
+
+#define for_each_online_gcwq_cpu(cpu) \
+ for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \
+ (cpu) < WORK_CPU_NONE; \
+ (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
+
+#define for_each_cwq_cpu(cpu, wq) \
+ for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \
+ (cpu) < WORK_CPU_NONE; \
+ (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
+
#ifdef CONFIG_DEBUG_OBJECTS_WORK

static struct debug_obj_descr work_debug_descr;
@@ -351,26 +390,46 @@ static bool workqueue_freezing; /* W: have wqs started freezing? */
static DEFINE_PER_CPU(struct global_cwq, global_cwq);
static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running);

+/*
+ * Global cpu workqueue and nr_running counter for unbound gcwq. The
+ * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
+ * workers have WORKER_UNBOUND set.
+ */
+static struct global_cwq unbound_global_cwq;
+static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */
+
static int worker_thread(void *__worker);

static struct global_cwq *get_gcwq(unsigned int cpu)
{
- return &per_cpu(global_cwq, cpu);
+ if (cpu != WORK_CPU_UNBOUND)
+ return &per_cpu(global_cwq, cpu);
+ else
+ return &unbound_global_cwq;
}

static atomic_t *get_gcwq_nr_running(unsigned int cpu)
{
- return &per_cpu(gcwq_nr_running, cpu);
+ if (cpu != WORK_CPU_UNBOUND)
+ return &per_cpu(gcwq_nr_running, cpu);
+ else
+ return &unbound_gcwq_nr_running;
}

static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
struct workqueue_struct *wq)
{
-#ifndef CONFIG_SMP
- return wq->cpu_wq.single;
+ if (!(wq->flags & WQ_UNBOUND)) {
+ if (likely(cpu < nr_cpu_ids)) {
+#ifdef CONFIG_SMP
+ return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
#else
- return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
+ return wq->cpu_wq.single;
#endif
+ }
+ } else if (likely(cpu == WORK_CPU_UNBOUND))
+ return wq->cpu_wq.single;
+ return NULL;
}

static unsigned int work_color_to_flags(int color)
@@ -453,7 +512,7 @@ static struct global_cwq *get_work_gcwq(struct work_struct *work)
if (cpu == WORK_CPU_NONE)
return NULL;

- BUG_ON(cpu >= nr_cpu_ids);
+ BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND);
return get_gcwq(cpu);
}

@@ -869,11 +928,14 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,

debug_work_activate(work);

+ if (unlikely(cpu == WORK_CPU_UNBOUND))
+ cpu = raw_smp_processor_id();
+
/*
* Determine gcwq to use. SINGLE_CPU is inherently
* NON_REENTRANT, so test it first.
*/
- if (!(wq->flags & WQ_SINGLE_CPU)) {
+ if (!(wq->flags & (WQ_SINGLE_CPU | WQ_UNBOUND))) {
struct global_cwq *last_gcwq;

/*
@@ -900,7 +962,7 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
}
} else
spin_lock_irqsave(&gcwq->lock, flags);
- } else {
+ } else if (!(wq->flags & WQ_UNBOUND)) {
unsigned int req_cpu = cpu;

/*
@@ -932,6 +994,9 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
spin_unlock_irqrestore(&gcwq->lock, flags);
goto retry;
}
+ } else {
+ gcwq = get_gcwq(WORK_CPU_UNBOUND);
+ spin_lock_irqsave(&gcwq->lock, flags);
}

/* gcwq determined, get cwq and queue */
@@ -1166,7 +1231,8 @@ static bool worker_maybe_bind_and_lock(struct worker *worker)
* it races with cpu hotunplug operation. Verify
* against GCWQ_DISASSOCIATED.
*/
- set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));
+ if (!(gcwq->flags & GCWQ_DISASSOCIATED))
+ set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));

spin_lock_irq(&gcwq->lock);
if (gcwq->flags & GCWQ_DISASSOCIATED)
@@ -1231,8 +1297,9 @@ static struct worker *alloc_worker(void)
*/
static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
{
- int id = -1;
+ bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND;
struct worker *worker = NULL;
+ int id = -1;

spin_lock_irq(&gcwq->lock);
while (ida_get_new(&gcwq->worker_ida, &id)) {
@@ -1250,8 +1317,12 @@ static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
worker->gcwq = gcwq;
worker->id = id;

- worker->task = kthread_create(worker_thread, worker, "kworker/%u:%d",
- gcwq->cpu, id);
+ if (!on_unbound_cpu)
+ worker->task = kthread_create(worker_thread, worker,
+ "kworker/%u:%d", gcwq->cpu, id);
+ else
+ worker->task = kthread_create(worker_thread, worker,
+ "kworker/u:%d", id);
if (IS_ERR(worker->task))
goto fail;

@@ -1260,10 +1331,13 @@ static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
* online later on. Make sure every worker has
* PF_THREAD_BOUND set.
*/
- if (bind)
+ if (bind && !on_unbound_cpu)
kthread_bind(worker->task, gcwq->cpu);
- else
+ else {
worker->task->flags |= PF_THREAD_BOUND;
+ if (on_unbound_cpu)
+ worker->flags |= WORKER_UNBOUND;
+ }

return worker;
fail:
@@ -1358,12 +1432,17 @@ static bool send_mayday(struct work_struct *work)
{
struct cpu_workqueue_struct *cwq = get_work_cwq(work);
struct workqueue_struct *wq = cwq->wq;
+ unsigned int cpu;

if (!(wq->flags & WQ_RESCUER))
return false;

/* mayday mayday mayday */
- if (!cpumask_test_and_set_cpu(cwq->gcwq->cpu, wq->mayday_mask))
+ cpu = cwq->gcwq->cpu;
+ /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
+ if (cpu == WORK_CPU_UNBOUND)
+ cpu = 0;
+ if (!cpumask_test_and_set_cpu(cpu, wq->mayday_mask))
wake_up_process(wq->rescuer->task);
return true;
}
@@ -1882,6 +1961,7 @@ static int rescuer_thread(void *__wq)
struct workqueue_struct *wq = __wq;
struct worker *rescuer = wq->rescuer;
struct list_head *scheduled = &rescuer->scheduled;
+ bool is_unbound = wq->flags & WQ_UNBOUND;
unsigned int cpu;

set_user_nice(current, RESCUER_NICE_LEVEL);
@@ -1891,8 +1971,13 @@ repeat:
if (kthread_should_stop())
return 0;

+ /*
+ * See whether any cpu is asking for help. Unbounded
+ * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
+ */
for_each_cpu(cpu, wq->mayday_mask) {
- struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+ unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
+ struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
struct global_cwq *gcwq = cwq->gcwq;
struct work_struct *work, *n;

@@ -2034,7 +2119,7 @@ static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
atomic_set(&wq->nr_cwqs_to_flush, 1);
}

- for_each_possible_cpu(cpu) {
+ for_each_cwq_cpu(cpu, wq) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
struct global_cwq *gcwq = cwq->gcwq;

@@ -2344,7 +2429,7 @@ static void wait_on_work(struct work_struct *work)
lock_map_acquire(&work->lockdep_map);
lock_map_release(&work->lockdep_map);

- for_each_possible_cpu(cpu)
+ for_each_gcwq_cpu(cpu)
wait_on_cpu_work(get_gcwq(cpu), work);
}

@@ -2590,23 +2675,25 @@ static int alloc_cwqs(struct workqueue_struct *wq)
const size_t size = sizeof(struct cpu_workqueue_struct);
const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
__alignof__(unsigned long long));
-#ifndef CONFIG_SMP
- void *ptr;

- /*
- * Allocate enough room to align cwq and put an extra pointer
- * at the end pointing back to the originally allocated
- * pointer which will be used for free.
- */
- ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
- if (ptr) {
- wq->cpu_wq.single = PTR_ALIGN(ptr, align);
- *(void **)(wq->cpu_wq.single + 1) = ptr;
+ if (CONFIG_SMP && !(wq->flags & WQ_UNBOUND)) {
+ /* on SMP, percpu allocator can align itself */
+ wq->cpu_wq.pcpu = __alloc_percpu(size, align);
+ } else {
+ void *ptr;
+
+ /*
+ * Allocate enough room to align cwq and put an extra
+ * pointer at the end pointing back to the originally
+ * allocated pointer which will be used for free.
+ */
+ ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
+ if (ptr) {
+ wq->cpu_wq.single = PTR_ALIGN(ptr, align);
+ *(void **)(wq->cpu_wq.single + 1) = ptr;
+ }
}
-#else
- /* On SMP, percpu allocator can align itself */
- wq->cpu_wq.pcpu = __alloc_percpu(size, align);
-#endif
+
/* just in case, make sure it's actually aligned */
BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align));
return wq->cpu_wq.v ? 0 : -ENOMEM;
@@ -2614,23 +2701,25 @@ static int alloc_cwqs(struct workqueue_struct *wq)

static void free_cwqs(struct workqueue_struct *wq)
{
-#ifndef CONFIG_SMP
- /* on UP, the pointer to free is stored right after the cwq */
- if (wq->cpu_wq.single)
+ if (CONFIG_SMP && !(wq->flags & WQ_UNBOUND))
+ free_percpu(wq->cpu_wq.pcpu);
+ else if (wq->cpu_wq.single) {
+ /* the pointer to free is stored right after the cwq */
kfree(*(void **)(wq->cpu_wq.single + 1));
-#else
- free_percpu(wq->cpu_wq.pcpu);
-#endif
+ }
}

-static int wq_clamp_max_active(int max_active, const char *name)
+static int wq_clamp_max_active(int max_active, unsigned int flags,
+ const char *name)
{
- if (max_active < 1 || max_active > WQ_MAX_ACTIVE)
+ int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
+
+ if (max_active < 1 || max_active > lim)
printk(KERN_WARNING "workqueue: max_active %d requested for %s "
"is out of range, clamping between %d and %d\n",
- max_active, name, 1, WQ_MAX_ACTIVE);
+ max_active, name, 1, lim);

- return clamp_val(max_active, 1, WQ_MAX_ACTIVE);
+ return clamp_val(max_active, 1, lim);
}

struct workqueue_struct *__alloc_workqueue_key(const char *name,
@@ -2642,8 +2731,15 @@ struct workqueue_struct *__alloc_workqueue_key(const char *name,
struct workqueue_struct *wq;
unsigned int cpu;

+ /*
+ * Unbound workqueues aren't concurrency managed and should be
+ * dispatched to workers immediately.
+ */
+ if (flags & WQ_UNBOUND)
+ flags |= WQ_HIGHPRI;
+
max_active = max_active ?: WQ_DFL_ACTIVE;
- max_active = wq_clamp_max_active(max_active, name);
+ max_active = wq_clamp_max_active(max_active, flags, name);

wq = kzalloc(sizeof(*wq), GFP_KERNEL);
if (!wq)
@@ -2664,7 +2760,7 @@ struct workqueue_struct *__alloc_workqueue_key(const char *name,
if (alloc_cwqs(wq) < 0)
goto err;

- for_each_possible_cpu(cpu) {
+ for_each_cwq_cpu(cpu, wq) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
struct global_cwq *gcwq = get_gcwq(cpu);

@@ -2703,7 +2799,7 @@ struct workqueue_struct *__alloc_workqueue_key(const char *name,
spin_lock(&workqueue_lock);

if (workqueue_freezing && wq->flags & WQ_FREEZEABLE)
- for_each_possible_cpu(cpu)
+ for_each_cwq_cpu(cpu, wq)
get_cwq(cpu, wq)->max_active = 0;

list_add(&wq->list, &workqueues);
@@ -2743,7 +2839,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
spin_unlock(&workqueue_lock);

/* sanity check */
- for_each_possible_cpu(cpu) {
+ for_each_cwq_cpu(cpu, wq) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
int i;

@@ -2777,13 +2873,13 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
{
unsigned int cpu;

- max_active = wq_clamp_max_active(max_active, wq->name);
+ max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);

spin_lock(&workqueue_lock);

wq->saved_max_active = max_active;

- for_each_possible_cpu(cpu) {
+ for_each_cwq_cpu(cpu, wq) {
struct global_cwq *gcwq = get_gcwq(cpu);

spin_lock_irq(&gcwq->lock);
@@ -3310,7 +3406,7 @@ void freeze_workqueues_begin(void)
BUG_ON(workqueue_freezing);
workqueue_freezing = true;

- for_each_possible_cpu(cpu) {
+ for_each_gcwq_cpu(cpu) {
struct global_cwq *gcwq = get_gcwq(cpu);
struct workqueue_struct *wq;

@@ -3322,7 +3418,7 @@ void freeze_workqueues_begin(void)
list_for_each_entry(wq, &workqueues, list) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);

- if (wq->flags & WQ_FREEZEABLE)
+ if (cwq && wq->flags & WQ_FREEZEABLE)
cwq->max_active = 0;
}

@@ -3354,7 +3450,7 @@ bool freeze_workqueues_busy(void)

BUG_ON(!workqueue_freezing);

- for_each_possible_cpu(cpu) {
+ for_each_gcwq_cpu(cpu) {
struct workqueue_struct *wq;
/*
* nr_active is monotonically decreasing. It's safe
@@ -3363,7 +3459,7 @@ bool freeze_workqueues_busy(void)
list_for_each_entry(wq, &workqueues, list) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);

- if (!(wq->flags & WQ_FREEZEABLE))
+ if (!cwq || !(wq->flags & WQ_FREEZEABLE))
continue;

BUG_ON(cwq->nr_active < 0);
@@ -3396,7 +3492,7 @@ void thaw_workqueues(void)
if (!workqueue_freezing)
goto out_unlock;

- for_each_possible_cpu(cpu) {
+ for_each_gcwq_cpu(cpu) {
struct global_cwq *gcwq = get_gcwq(cpu);
struct workqueue_struct *wq;

@@ -3408,7 +3504,7 @@ void thaw_workqueues(void)
list_for_each_entry(wq, &workqueues, list) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);

- if (!(wq->flags & WQ_FREEZEABLE))
+ if (!cwq || !(wq->flags & WQ_FREEZEABLE))
continue;

/* restore max_active and repopulate worklist */
@@ -3451,12 +3547,14 @@ void __init init_workqueues(void)
hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);

/* initialize gcwqs */
- for_each_possible_cpu(cpu) {
+ for_each_gcwq_cpu(cpu) {
struct global_cwq *gcwq = get_gcwq(cpu);

spin_lock_init(&gcwq->lock);
INIT_LIST_HEAD(&gcwq->worklist);
gcwq->cpu = cpu;
+ if (cpu == WORK_CPU_UNBOUND)
+ gcwq->flags |= GCWQ_DISASSOCIATED;

INIT_LIST_HEAD(&gcwq->idle_list);
for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
@@ -3476,7 +3574,7 @@ void __init init_workqueues(void)
}

/* create the initial worker */
- for_each_online_cpu(cpu) {
+ for_each_online_gcwq_cpu(cpu) {
struct global_cwq *gcwq = get_gcwq(cpu);
struct worker *worker;

@@ -3490,5 +3588,7 @@ void __init init_workqueues(void)
system_wq = alloc_workqueue("events", 0, 0);
system_long_wq = alloc_workqueue("events_long", 0, 0);
system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0);
+ system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
+ WQ_UNBOUND_MAX_ACTIVE);
BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq);
}
--
1.6.4.2

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Prev: [PATCH 4/4] async: use workqueue for worker pool
Next: 2.6.34: simple IOMMU API extension to check safe interrupt remapping