From: Lai Jiangshan Date: Tue, 20 May 2014 09:46:31 +0000 (+0800) Subject: workqueue: separate iteration role from worker_idr X-Git-Tag: firefly_0821_release~176^2~3812^2~11 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=da028469ba173e9c634b6ecf80bb0c69c7d1024d;p=firefly-linux-kernel-4.4.55.git workqueue: separate iteration role from worker_idr worker_idr has the iteration (iterating for attached workers) and worker ID duties. These two duties don't have to be tied together. We can separate them and use a list for tracking attached workers and iteration. Before this separation, it wasn't possible to add rescuer workers to worker_idr due to rescuer workers couldn't allocate ID dynamically because ID-allocation depends on memory-allocation, which rescuer can't depend on. After separation, we can easily add the rescuer workers to the list for iteration without any memory-allocation. It is required when we attach the rescuer worker to the pool in later patch. tj: Minor description updates. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo --- diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 938836bc6207..a6c38b717957 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -161,7 +161,8 @@ 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 and iteration */ + struct idr worker_idr; /* M: worker IDs */ + struct list_head workers; /* M: attached workers */ struct completion *detach_completion; /* all workers detached */ struct workqueue_attrs *attrs; /* I: worker attributes */ @@ -363,7 +364,6 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to, /** * for_each_pool_worker - iterate through all workers of a worker_pool * @worker: iteration cursor - * @wi: integer used for iteration * @pool: worker_pool to iterate workers of * * This must be called with @pool->manager_mutex. @@ -371,8 +371,8 @@ static void copy_workqueue_attrs(struct workqueue_attrs *to, * The if/else clause exists only for the lockdep assertion and can be * ignored. */ -#define for_each_pool_worker(worker, wi, pool) \ - idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \ +#define for_each_pool_worker(worker, pool) \ + list_for_each_entry((worker), &(pool)->workers, node) \ if (({ lockdep_assert_held(&pool->manager_mutex); false; })) { } \ else @@ -1674,6 +1674,7 @@ static struct worker *alloc_worker(void) if (worker) { INIT_LIST_HEAD(&worker->entry); INIT_LIST_HEAD(&worker->scheduled); + INIT_LIST_HEAD(&worker->node); /* on creation a worker is in !idle && prep state */ worker->flags = WORKER_PREP; } @@ -1696,7 +1697,8 @@ static void worker_detach_from_pool(struct worker *worker, mutex_lock(&pool->manager_mutex); idr_remove(&pool->worker_idr, worker->id); - if (idr_is_empty(&pool->worker_idr)) + list_del(&worker->node); + if (list_empty(&pool->workers)) detach_completion = pool->detach_completion; mutex_unlock(&pool->manager_mutex); @@ -1772,6 +1774,8 @@ static struct worker *create_worker(struct worker_pool *pool) /* 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); return worker; @@ -3483,6 +3487,7 @@ 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); INIT_HLIST_NODE(&pool->hash_node); pool->refcnt = 1; @@ -3548,7 +3553,7 @@ static void put_unbound_pool(struct worker_pool *pool) spin_unlock_irq(&pool->lock); mutex_lock(&pool->manager_mutex); - if (!idr_is_empty(&pool->worker_idr)) + if (!list_empty(&pool->workers)) pool->detach_completion = &detach_completion; mutex_unlock(&pool->manager_mutex); @@ -4533,7 +4538,6 @@ static void wq_unbind_fn(struct work_struct *work) int cpu = smp_processor_id(); struct worker_pool *pool; struct worker *worker; - int wi; for_each_cpu_worker_pool(pool, cpu) { WARN_ON_ONCE(cpu != smp_processor_id()); @@ -4548,7 +4552,7 @@ static void wq_unbind_fn(struct work_struct *work) * before the last CPU down must be on the cpu. After * this, they may become diasporas. */ - for_each_pool_worker(worker, wi, pool) + for_each_pool_worker(worker, pool) worker->flags |= WORKER_UNBOUND; pool->flags |= POOL_DISASSOCIATED; @@ -4594,7 +4598,6 @@ static void wq_unbind_fn(struct work_struct *work) static void rebind_workers(struct worker_pool *pool) { struct worker *worker; - int wi; lockdep_assert_held(&pool->manager_mutex); @@ -4605,13 +4608,13 @@ static void rebind_workers(struct worker_pool *pool) * of all workers first and then clear UNBOUND. As we're called * from CPU_ONLINE, the following shouldn't fail. */ - for_each_pool_worker(worker, wi, pool) + for_each_pool_worker(worker, pool) WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask) < 0); spin_lock_irq(&pool->lock); - for_each_pool_worker(worker, wi, pool) { + for_each_pool_worker(worker, pool) { unsigned int worker_flags = worker->flags; /* @@ -4663,7 +4666,6 @@ static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) { static cpumask_t cpumask; struct worker *worker; - int wi; lockdep_assert_held(&pool->manager_mutex); @@ -4677,7 +4679,7 @@ static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) return; /* as we're called from CPU_ONLINE, the following shouldn't fail */ - for_each_pool_worker(worker, wi, pool) + for_each_pool_worker(worker, pool) WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask) < 0); } diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h index 7e2204db0b1a..8888e0672442 100644 --- a/kernel/workqueue_internal.h +++ b/kernel/workqueue_internal.h @@ -37,6 +37,8 @@ struct worker { struct task_struct *task; /* I: worker task */ struct worker_pool *pool; /* I: the associated pool */ /* L: for rescuers */ + struct list_head node; /* M: anchored at pool->workers */ + /* M: runs through worker->node */ unsigned long last_active; /* L: last active timestamp */ unsigned int flags; /* X: flags */