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workqueue: implement several utility APIs

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Implement the following utility APIs.

 workqueue_set_max_active()	: adjust max_active of a wq
 workqueue_congested()		: test whether a wq is contested
 work_cpu()			: determine the last / current cpu of a work
 work_busy()			: query whether a work is busy

* Anton Blanchard fixed missing ret initialization in work_busy().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Anton Blanchard <anton@samba.org>
This commit is contained in:
Tejun Heo 2010-06-29 10:07:14 +02:00
parent d320c03830
commit dcd989cb73
2 changed files with 117 additions and 2 deletions
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11
include/linux/workqueue.h
View File

@ -61,6 +61,10 @@ enum {
WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
WORK_STRUCT_NO_CPU = NR_CPUS << WORK_STRUCT_FLAG_BITS,
/* bit mask for work_busy() return values */
WORK_BUSY_PENDING = 1 << 0,
WORK_BUSY_RUNNING = 1 << 1,
};
struct work_struct {
@ -307,9 +311,14 @@ extern void init_workqueues(void);
int execute_in_process_context(work_func_t fn, struct execute_work *);
extern int flush_work(struct work_struct *work);
extern int cancel_work_sync(struct work_struct *work);
extern void workqueue_set_max_active(struct workqueue_struct *wq,
int max_active);
extern bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq);
extern unsigned int work_cpu(struct work_struct *work);
extern unsigned int work_busy(struct work_struct *work);
/*
* Kill off a pending schedule_delayed_work(). Note that the work callback
* function may still be running on return from cancel_delayed_work(), unless

108
kernel/workqueue.c
View File

@ -203,7 +203,7 @@ struct workqueue_struct {
cpumask_var_t mayday_mask; /* cpus requesting rescue */
struct worker *rescuer; /* I: rescue worker */
int saved_max_active; /* I: saved cwq max_active */
int saved_max_active; /* W: saved cwq max_active */
const char *name; /* I: workqueue name */
#ifdef CONFIG_LOCKDEP
struct lockdep_map lockdep_map;
@ -2675,6 +2675,112 @@ void destroy_workqueue(struct workqueue_struct *wq)
}
EXPORT_SYMBOL_GPL(destroy_workqueue);
/**
* workqueue_set_max_active - adjust max_active of a workqueue
* @wq: target workqueue
* @max_active: new max_active value.
*
* Set max_active of @wq to @max_active.
*
* CONTEXT:
* Don't call from IRQ context.
*/
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);
spin_lock(&workqueue_lock);
wq->saved_max_active = max_active;
for_each_possible_cpu(cpu) {
struct global_cwq *gcwq = get_gcwq(cpu);
spin_lock_irq(&gcwq->lock);
if (!(wq->flags & WQ_FREEZEABLE) ||
!(gcwq->flags & GCWQ_FREEZING))
get_cwq(gcwq->cpu, wq)->max_active = max_active;
spin_unlock_irq(&gcwq->lock);
}
spin_unlock(&workqueue_lock);
}
EXPORT_SYMBOL_GPL(workqueue_set_max_active);
/**
* workqueue_congested - test whether a workqueue is congested
* @cpu: CPU in question
* @wq: target workqueue
*
* Test whether @wq's cpu workqueue for @cpu is congested. There is
* no synchronization around this function and the test result is
* unreliable and only useful as advisory hints or for debugging.
*
* RETURNS:
* %true if congested, %false otherwise.
*/
bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq)
{
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
return !list_empty(&cwq->delayed_works);
}
EXPORT_SYMBOL_GPL(workqueue_congested);
/**
* work_cpu - return the last known associated cpu for @work
* @work: the work of interest
*
* RETURNS:
* CPU number if @work was ever queued. NR_CPUS otherwise.
*/
unsigned int work_cpu(struct work_struct *work)
{
struct global_cwq *gcwq = get_work_gcwq(work);
return gcwq ? gcwq->cpu : NR_CPUS;
}
EXPORT_SYMBOL_GPL(work_cpu);
/**
* work_busy - test whether a work is currently pending or running
* @work: the work to be tested
*
* Test whether @work is currently pending or running. There is no
* synchronization around this function and the test result is
* unreliable and only useful as advisory hints or for debugging.
* Especially for reentrant wqs, the pending state might hide the
* running state.
*
* RETURNS:
* OR'd bitmask of WORK_BUSY_* bits.
*/
unsigned int work_busy(struct work_struct *work)
{
struct global_cwq *gcwq = get_work_gcwq(work);
unsigned long flags;
unsigned int ret = 0;
if (!gcwq)
return false;
spin_lock_irqsave(&gcwq->lock, flags);
if (work_pending(work))
ret |= WORK_BUSY_PENDING;
if (find_worker_executing_work(gcwq, work))
ret |= WORK_BUSY_RUNNING;
spin_unlock_irqrestore(&gcwq->lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(work_busy);
/*
* CPU hotplug.
*