[PATCH V3 06/10] workqueue: convert worker_idr to worker_ida

Lai Jiangshan
2014-05-20T09:43:07Z

We don't need to iterate workers via worker_idr, worker_idr is
used for allocating/freeing ID only, so we convert it to worker_ida.

By using ida_simple_get/remove(), worker_ida can be protected by itself,
so we don't need manager_mutex to protect it and the ID-removal code
is allowed to be moved out from worker_detach_from_pool().

And in later patch, worker_detach_from_pool() will be used in rescuers
which doesn't have IDs, so we directly move the ID-removal code out
from worker_detach_from_pool().

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
kernel/workqueue.c | 20 ++++++++------------
1 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index fd2f265..637c244 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -161,10 +161,11 @@ struct worker_pool {
/* see manage_workers() for details on the two manager mutexes */
struct mutex manager_arb; /* manager arbitration */
struct mutex manager_mutex; /* manager exclusion */
- struct idr worker_idr; /* M: worker IDs */
struct list_head workers; /* M: attached workers */
struct completion *detach_completion; /* all workers detached */

+ struct ida worker_ida; /* worker IDs for task name */
+
struct workqueue_attrs *attrs; /* I: worker attributes */
struct hlist_node hash_node; /* PL: unbound_pool_hash node */
int refcnt; /* PL: refcnt for unbound pools */
@@ -1696,7 +1697,6 @@ static void worker_detach_from_pool(struct worker *worker,
struct completion *detach_completion = NULL;

mutex_lock(&pool->manager_mutex);
- idr_remove(&pool->worker_idr, worker->id);
list_del(&worker->node);
if (list_empty(&pool->workers))
detach_completion = pool->detach_completion;
@@ -1727,11 +1727,8 @@ static struct worker *create_worker(struct worker_pool *pool)

lockdep_assert_held(&pool->manager_mutex);

- /*
- * ID is needed to determine kthread name. Allocate ID first
- * without installing the pointer.
- */
- id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_KERNEL);
+ /* ID is needed to determine kthread name. */
+ id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL);
if (id < 0)
goto fail;

@@ -1772,8 +1769,6 @@ static struct worker *create_worker(struct worker_pool *pool)
if (pool->flags & POOL_DISASSOCIATED)
worker->flags |= WORKER_UNBOUND;

- /* successful, commit the pointer to idr */
- idr_replace(&pool->worker_idr, worker, worker->id);
/* successful, attach the worker to the pool */
list_add_tail(&worker->node, &pool->workers);

@@ -1781,7 +1776,7 @@ static struct worker *create_worker(struct worker_pool *pool)

fail:
if (id >= 0)
- idr_remove(&pool->worker_idr, id);
+ ida_simple_remove(&pool->worker_ida, id);
kfree(worker);
return NULL;
}
@@ -2250,6 +2245,7 @@ woke_up:
worker->task->flags &= ~PF_WQ_WORKER;

set_task_comm(worker->task, "kworker/dying");
+ ida_simple_remove(&pool->worker_ida, worker->id);
worker_detach_from_pool(worker, pool);
kfree(worker);
return 0;
@@ -3486,9 +3482,9 @@ static int init_worker_pool(struct worker_pool *pool)

mutex_init(&pool->manager_arb);
mutex_init(&pool->manager_mutex);
- idr_init(&pool->worker_idr);
INIT_LIST_HEAD(&pool->workers);

+ ida_init(&pool->worker_ida);
INIT_HLIST_NODE(&pool->hash_node);
pool->refcnt = 1;

@@ -3503,7 +3499,7 @@ static void rcu_free_pool(struct rcu_head *rcu)
{
struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);

- idr_destroy(&pool->worker_idr);
+ ida_destroy(&pool->worker_ida);
free_workqueue_attrs(pool->attrs);
kfree(pool);
}
--
1.7.4.4