Commit da028469 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Tejun Heo
Browse files

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: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 3347fc9f
......@@ -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);
}
......
......@@ -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 */
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment