workqueue: use manager lock only to protect worker_idr (9625ab17) · Commits · e / devices / android_kernel_fairphone_FP5

kernel/workqueue.c

+6 −28

Original line number	Original line	Diff line number	Diff line
	@@ -124,8 +124,7 @@ enum {
	* cpu or grabbing pool->lock is enough for read access. If		* cpu or grabbing pool->lock is enough for read access. If
	* POOL_DISASSOCIATED is set, it's identical to L.		* POOL_DISASSOCIATED is set, it's identical to L.
	*		*
	* MG: pool->manager_mutex and pool->lock protected. Writes require both		* M: pool->manager_mutex protected.
	* locks. Reads can happen under either lock.
	*		*
	* PL: wq_pool_mutex protected.		* PL: wq_pool_mutex protected.
	*		*
	@@ -164,7 +163,7 @@ struct worker_pool {
	/* see manage_workers() for details on the two manager mutexes */		/* see manage_workers() for details on the two manager mutexes */
	struct mutex manager_arb; /* manager arbitration */		struct mutex manager_arb; /* manager arbitration */
	struct mutex manager_mutex; /* manager exclusion */		struct mutex manager_mutex; /* manager exclusion */
	struct idr worker_idr; /* MG: worker IDs and iteration */		struct idr worker_idr; /* M: worker IDs and iteration */

	struct workqueue_attrs attrs; / I: worker attributes */		struct workqueue_attrs attrs; / I: worker attributes */
	struct hlist_node hash_node; /* PL: unbound_pool_hash node */		struct hlist_node hash_node; /* PL: unbound_pool_hash node */
	@@ -340,16 +339,6 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to,
	lockdep_is_held(&wq->mutex), \		lockdep_is_held(&wq->mutex), \
	"sched RCU or wq->mutex should be held")		"sched RCU or wq->mutex should be held")

	#ifdef CONFIG_LOCKDEP
	#define assert_manager_or_pool_lock(pool) \
	WARN_ONCE(debug_locks && \
	!lockdep_is_held(&(pool)->manager_mutex) && \
	!lockdep_is_held(&(pool)->lock), \
	"pool->manager_mutex or ->lock should be held")
	#else
	#define assert_manager_or_pool_lock(pool) do { } while (0)
	#endif

	#define for_each_cpu_worker_pool(pool, cpu) \		#define for_each_cpu_worker_pool(pool, cpu) \
	for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \		for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
	(pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \		(pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
	@@ -378,14 +367,14 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to,
	* @wi: integer used for iteration		* @wi: integer used for iteration
	* @pool: worker_pool to iterate workers of		* @pool: worker_pool to iterate workers of
	*		*
	* This must be called with either @pool->manager_mutex or ->lock held.		* This must be called with @pool->manager_mutex.
	*		*
	* The if/else clause exists only for the lockdep assertion and can be		* The if/else clause exists only for the lockdep assertion and can be
	* ignored.		* ignored.
	*/		*/
	#define for_each_pool_worker(worker, wi, pool) \		#define for_each_pool_worker(worker, wi, pool) \
	idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \		idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \
	if (({ assert_manager_or_pool_lock((pool)); false; })) { } \		if (({ lockdep_assert_held(&pool->manager_mutex); false; })) { } \
	else		else

	/**		/**
	@@ -1725,13 +1714,7 @@ static struct worker create_worker(struct worker_pool pool)
	* ID is needed to determine kthread name. Allocate ID first		* ID is needed to determine kthread name. Allocate ID first
	* without installing the pointer.		* without installing the pointer.
	*/		*/
	idr_preload(GFP_KERNEL);		id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_KERNEL);
	spin_lock_irq(&pool->lock);

	id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_NOWAIT);

	spin_unlock_irq(&pool->lock);
	idr_preload_end();
	if (id < 0)		if (id < 0)
	goto fail;		goto fail;

	@@ -1773,18 +1756,13 @@ static struct worker create_worker(struct worker_pool pool)
	worker->flags \|= WORKER_UNBOUND;		worker->flags \|= WORKER_UNBOUND;

	/* successful, commit the pointer to idr */		/* successful, commit the pointer to idr */
	spin_lock_irq(&pool->lock);
	idr_replace(&pool->worker_idr, worker, worker->id);		idr_replace(&pool->worker_idr, worker, worker->id);
	spin_unlock_irq(&pool->lock);

	return worker;		return worker;

	fail:		fail:
	if (id >= 0) {		if (id >= 0)
	spin_lock_irq(&pool->lock);
	idr_remove(&pool->worker_idr, id);		idr_remove(&pool->worker_idr, id);
	spin_unlock_irq(&pool->lock);
	}
	kfree(worker);		kfree(worker);
	return NULL;		return NULL;
	}		}