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workqueue: separate pool-attaching code out from create_worker()

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Currently, the code to attach a new worker to its pool is embedded in
create_worker().  Separating this code out will make the codes clearer
and will allow rescuers to share the code path later.

tj: Description and comment updates.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Lai Jiangshan 2014-05-20 17:46:35 +08:00 committed by Tejun Heo
parent 92f9c5c40c
commit 4736cbf7a4
1 changed files with 38 additions and 23 deletions
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61
kernel/workqueue.c
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@ -66,7 +66,7 @@ enum {
*
* Note that DISASSOCIATED should be flipped only while holding
* attach_mutex to avoid changing binding state while
* create_worker() is in progress.
* worker_attach_to_pool() is in progress.
*/
POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
POOL_FREEZING = 1 << 3, /* freeze in progress */
@ -1682,14 +1682,47 @@ static struct worker *alloc_worker(void)
return worker;
}
/**
* worker_attach_to_pool() - attach a worker to a pool
* @worker: worker to be attached
* @pool: the target pool
*
* Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
* cpu-binding of @worker are kept coordinated with the pool across
* cpu-[un]hotplugs.
*/
static void worker_attach_to_pool(struct worker *worker,
struct worker_pool *pool)
{
mutex_lock(&pool->attach_mutex);
/*
* set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
* online CPUs. It'll be re-applied when any of the CPUs come up.
*/
set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
/*
* The pool->attach_mutex ensures %POOL_DISASSOCIATED remains
* stable across this function. See the comments above the
* flag definition for details.
*/
if (pool->flags & POOL_DISASSOCIATED)
worker->flags |= WORKER_UNBOUND;
list_add_tail(&worker->node, &pool->workers);
mutex_unlock(&pool->attach_mutex);
}
/**
* worker_detach_from_pool() - detach a worker from its pool
* @worker: worker which is attached to its pool
* @pool: the pool @worker is attached to
*
* Undo the attaching which had been done in create_worker(). The caller
* worker shouldn't access to the pool after detached except it has other
* reference to the pool.
* Undo the attaching which had been done in worker_attach_to_pool(). The
* caller worker shouldn't access to the pool after detached except it has
* other reference to the pool.
*/
static void worker_detach_from_pool(struct worker *worker,
struct worker_pool *pool)
@ -1753,26 +1786,8 @@ static struct worker *create_worker(struct worker_pool *pool)
/* prevent userland from meddling with cpumask of workqueue workers */
worker->task->flags |= PF_NO_SETAFFINITY;
mutex_lock(&pool->attach_mutex);
/*
* set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
* online CPUs. It'll be re-applied when any of the CPUs come up.
*/
set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
/*
* The pool->attach_mutex ensures %POOL_DISASSOCIATED
* remains stable across this function. See the comments above the
* flag definition for details.
*/
if (pool->flags & POOL_DISASSOCIATED)
worker->flags |= WORKER_UNBOUND;
/* successful, attach the worker to the pool */
list_add_tail(&worker->node, &pool->workers);
mutex_unlock(&pool->attach_mutex);
worker_attach_to_pool(worker, pool);
return worker;