workqueue: separate pool-attaching code out from create_worker()
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>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 38b9ea7..b1de6ac 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -66,7 +66,7 @@
*
* 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 */
@@ -1683,13 +1683,46 @@
}
/**
+ * 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 @@
/* 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;