[PATCH 04/17] workqueue: make GCWQ_FREEZING a pool flag

Tejun Heo
2013-01-17T01:43:03Z

Make GCWQ_FREEZING a pool flag POOL_FREEZING. This patch doesn't
change locking - FREEZING on both pools of a CPU are set or clear
together while holding gcwq->lock. It shouldn't cause any functional
difference.

This leaves gcwq->flags w/o any flags. Removed.

While at it, convert BUG_ON()s in freeze_workqueue_begin() and
thaw_workqueues() to WARN_ON_ONCE().

This is part of an effort to remove global_cwq and make worker_pool
the top level abstraction, which in turn will help implementing worker
pools with user-specified attributes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
kernel/workqueue.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 8feef7e..6e8bad6 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -47,11 +47,6 @@

enum {
/*
- * global_cwq flags
- */
- GCWQ_FREEZING = 1 << 1, /* freeze in progress */
-
- /*
* worker_pool flags
*
* A bound pool is either associated or disassociated with its CPU.
@@ -70,6 +65,7 @@ enum {
POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
POOL_MANAGING_WORKERS = 1 << 1, /* managing workers */
POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
+ POOL_FREEZING = 1 << 3, /* freeze in progress */

/* worker flags */
WORKER_STARTED = 1 << 0, /* started */
@@ -179,7 +175,6 @@ struct worker_pool {
struct global_cwq {
spinlock_t lock; /* the gcwq lock */
unsigned int cpu; /* I: the associated cpu */
- unsigned int flags; /* L: GCWQ_* flags */

/* workers are chained either in busy_hash or pool idle_list */
DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
@@ -3389,13 +3384,15 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
wq->saved_max_active = max_active;

for_each_cwq_cpu(cpu, wq) {
- struct global_cwq *gcwq = get_gcwq(cpu);
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+ struct worker_pool *pool = cwq->pool;
+ struct global_cwq *gcwq = pool->gcwq;

spin_lock_irq(&gcwq->lock);

if (!(wq->flags & WQ_FREEZABLE) ||
- !(gcwq->flags & GCWQ_FREEZING))
- cwq_set_max_active(get_cwq(gcwq->cpu, wq), max_active);
+ !(pool->flags & POOL_FREEZING))
+ cwq_set_max_active(cwq, max_active);

spin_unlock_irq(&gcwq->lock);
}
@@ -3685,12 +3682,15 @@ void freeze_workqueues_begin(void)

for_each_gcwq_cpu(cpu) {
struct global_cwq *gcwq = get_gcwq(cpu);
+ struct worker_pool *pool;
struct workqueue_struct *wq;

spin_lock_irq(&gcwq->lock);

- BUG_ON(gcwq->flags & GCWQ_FREEZING);
- gcwq->flags |= GCWQ_FREEZING;
+ for_each_worker_pool(pool, gcwq) {
+ WARN_ON_ONCE(pool->flags & POOL_FREEZING);
+ pool->flags |= POOL_FREEZING;
+ }

list_for_each_entry(wq, &workqueues, list) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
@@ -3776,8 +3776,10 @@ void thaw_workqueues(void)

spin_lock_irq(&gcwq->lock);

- BUG_ON(!(gcwq->flags & GCWQ_FREEZING));
- gcwq->flags &= ~GCWQ_FREEZING;
+ for_each_worker_pool(pool, gcwq) {
+ WARN_ON_ONCE(!(pool->flags & POOL_FREEZING));
+ pool->flags &= ~POOL_FREEZING;
+ }

list_for_each_entry(wq, &workqueues, list) {
struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
--
1.8.0.2