workqueue: move gcwq_associate() under CPU hotplug section

gcwq_associate() is now more involved with CPU hotplug and its current
location requires forward declarations of
gcwq_claim/release_management().  Move it under CPU hotplug section
and remove the prototypes.

This patch is pure relocation.  Nothing else changes.

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 3787d3194d3777b1c8184d39b635ca97bdd2c48e..f12b9bc00a5cc6777364171b0613363b78b749de 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -479,8 +479,6 @@ static atomic_t unbound_pool_nr_running[NR_WORKER_POOLS] = {
 };
 
 static int worker_thread(void *__worker);
-static void gcwq_claim_management(struct global_cwq *gcwq);
-static void gcwq_release_management(struct global_cwq *gcwq);
 
 static int worker_pool_pri(struct worker_pool *pool)
 {
@@ -1662,153 +1660,6 @@ static void busy_worker_rebind_fn(struct work_struct *work)
        spin_unlock_irq(&gcwq->lock);
 }
 
-/**
- * gcwq_associate - (re)associate a gcwq to its CPU and rebind its workers
- * @gcwq: gcwq of interest
- *
- * @gcwq->cpu is coming online.  Clear %GCWQ_DISASSOCIATED and rebind all
- * workers to the CPU.  Rebinding is different for idle and busy ones.
- *
- * The idle ones should be rebound synchronously and idle rebinding should
- * be complete before any worker starts executing work items with
- * concurrency management enabled; otherwise, scheduler may oops trying to
- * wake up non-local idle worker from wq_worker_sleeping().
- *
- * This is achieved by repeatedly requesting rebinding until all idle
- * workers are known to have been rebound under @gcwq->lock and holding all
- * idle workers from becoming busy until idle rebinding is complete.
- *
- * Once idle workers are rebound, busy workers can be rebound as they
- * finish executing their current work items.  Queueing the rebind work at
- * the head of their scheduled lists is enough.  Note that nr_running will
- * be properbly bumped as busy workers rebind.
- *
- * On return, all workers are guaranteed to either be bound or have rebind
- * work item scheduled.
- */
-static void gcwq_associate(struct global_cwq *gcwq)
-{
-       struct idle_rebind idle_rebind;
-       struct worker_pool *pool;
-       struct worker *worker;
-       struct hlist_node *pos;
-       int i;
-
-       gcwq_claim_management(gcwq);
-       spin_lock_irq(&gcwq->lock);
-
-       gcwq->flags &= ~GCWQ_DISASSOCIATED;
-
-       /*
-        * Rebind idle workers.  Interlocked both ways.  We wait for
-        * workers to rebind via @idle_rebind.done.  Workers will wait for
-        * us to finish up by watching %WORKER_REBIND.
-        */
-       init_completion(&idle_rebind.done);
-retry:
-       idle_rebind.cnt = 1;
-       INIT_COMPLETION(idle_rebind.done);
-
-       /* set REBIND and kick idle ones, we'll wait for these later */
-       for_each_worker_pool(pool, gcwq) {
-               list_for_each_entry(worker, &pool->idle_list, entry) {
-                       unsigned long worker_flags = worker->flags;
-
-                       if (worker->flags & WORKER_REBIND)
-                               continue;
-
-                       /* morph UNBOUND to REBIND atomically */
-                       worker_flags &= ~WORKER_UNBOUND;
-                       worker_flags |= WORKER_REBIND;
-                       ACCESS_ONCE(worker->flags) = worker_flags;
-
-                       idle_rebind.cnt++;
-                       worker->idle_rebind = &idle_rebind;
-
-                       /* worker_thread() will call idle_worker_rebind() */
-                       wake_up_process(worker->task);
-               }
-       }
-
-       if (--idle_rebind.cnt) {
-               spin_unlock_irq(&gcwq->lock);
-               wait_for_completion(&idle_rebind.done);
-               spin_lock_irq(&gcwq->lock);
-               /* busy ones might have become idle while waiting, retry */
-               goto retry;
-       }
-
-       /* all idle workers are rebound, rebind busy workers */
-       for_each_busy_worker(worker, i, pos, gcwq) {
-               unsigned long worker_flags = worker->flags;
-               struct work_struct *rebind_work = &worker->rebind_work;
-               struct workqueue_struct *wq;
-
-               /* morph UNBOUND to REBIND atomically */
-               worker_flags &= ~WORKER_UNBOUND;
-               worker_flags |= WORKER_REBIND;
-               ACCESS_ONCE(worker->flags) = worker_flags;
-
-               if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
-                                    work_data_bits(rebind_work)))
-                       continue;
-
-               debug_work_activate(rebind_work);
-
-               /*
-                * wq doesn't really matter but let's keep @worker->pool
-                * and @cwq->pool consistent for sanity.
-                */
-               if (worker_pool_pri(worker->pool))
-                       wq = system_highpri_wq;
-               else
-                       wq = system_wq;
-
-               insert_work(get_cwq(gcwq->cpu, wq), rebind_work,
-                       worker->scheduled.next,
-                       work_color_to_flags(WORK_NO_COLOR));
-       }
-
-       /*
-        * At this point, each pool is guaranteed to have at least one idle
-        * worker and all idle workers are waiting for WORKER_REBIND to
-        * clear.  Release management before releasing idle workers;
-        * otherwise, they can all go become busy as we're holding the
-        * manager_mutexes, which can lead to deadlock as we don't actually
-        * create new workers.
-        */
-       gcwq_release_management(gcwq);
-
-       /*
-        * Clear %WORKER_REBIND and release.  Clearing it from this foreign
-        * context is safe because these workers are still guaranteed to be
-        * idle.
-        *
-        * We need to make sure all idle workers passed WORKER_REBIND wait
-        * in idle_worker_rebind() before returning; otherwise, workers can
-        * get stuck at the wait if hotplug cycle repeats.
-        */
-       idle_rebind.cnt = 1;
-       INIT_COMPLETION(idle_rebind.done);
-
-       for_each_worker_pool(pool, gcwq) {
-               WARN_ON_ONCE(list_empty(&pool->idle_list));
-               list_for_each_entry(worker, &pool->idle_list, entry) {
-                       worker->flags &= ~WORKER_REBIND;
-                       idle_rebind.cnt++;
-               }
-       }
-
-       wake_up_all(&gcwq->rebind_hold);
-
-       if (--idle_rebind.cnt) {
-               spin_unlock_irq(&gcwq->lock);
-               wait_for_completion(&idle_rebind.done);
-       } else {
-               spin_unlock_irq(&gcwq->lock);
-       }
-}
-
 static struct worker *alloc_worker(void)
 {
        struct worker *worker;
@@ -3537,6 +3388,153 @@ static void gcwq_release_management(struct global_cwq *gcwq)
                mutex_unlock(&pool->manager_mutex);
 }
 
+/**
+ * gcwq_associate - (re)associate a gcwq to its CPU and rebind its workers
+ * @gcwq: gcwq of interest
+ *
+ * @gcwq->cpu is coming online.  Clear %GCWQ_DISASSOCIATED and rebind all
+ * workers to the CPU.  Rebinding is different for idle and busy ones.
+ *
+ * The idle ones should be rebound synchronously and idle rebinding should
+ * be complete before any worker starts executing work items with
+ * concurrency management enabled; otherwise, scheduler may oops trying to
+ * wake up non-local idle worker from wq_worker_sleeping().
+ *
+ * This is achieved by repeatedly requesting rebinding until all idle
+ * workers are known to have been rebound under @gcwq->lock and holding all
+ * idle workers from becoming busy until idle rebinding is complete.
+ *
+ * Once idle workers are rebound, busy workers can be rebound as they
+ * finish executing their current work items.  Queueing the rebind work at
+ * the head of their scheduled lists is enough.  Note that nr_running will
+ * be properbly bumped as busy workers rebind.
+ *
+ * On return, all workers are guaranteed to either be bound or have rebind
+ * work item scheduled.
+ */
+static void gcwq_associate(struct global_cwq *gcwq)
+{
+       struct idle_rebind idle_rebind;
+       struct worker_pool *pool;
+       struct worker *worker;
+       struct hlist_node *pos;
+       int i;
+
+       gcwq_claim_management(gcwq);
+       spin_lock_irq(&gcwq->lock);
+
+       gcwq->flags &= ~GCWQ_DISASSOCIATED;
+
+       /*
+        * Rebind idle workers.  Interlocked both ways.  We wait for
+        * workers to rebind via @idle_rebind.done.  Workers will wait for
+        * us to finish up by watching %WORKER_REBIND.
+        */
+       init_completion(&idle_rebind.done);
+retry:
+       idle_rebind.cnt = 1;
+       INIT_COMPLETION(idle_rebind.done);
+
+       /* set REBIND and kick idle ones, we'll wait for these later */
+       for_each_worker_pool(pool, gcwq) {
+               list_for_each_entry(worker, &pool->idle_list, entry) {
+                       unsigned long worker_flags = worker->flags;
+
+                       if (worker->flags & WORKER_REBIND)
+                               continue;
+
+                       /* morph UNBOUND to REBIND atomically */
+                       worker_flags &= ~WORKER_UNBOUND;
+                       worker_flags |= WORKER_REBIND;
+                       ACCESS_ONCE(worker->flags) = worker_flags;
+
+                       idle_rebind.cnt++;
+                       worker->idle_rebind = &idle_rebind;
+
+                       /* worker_thread() will call idle_worker_rebind() */
+                       wake_up_process(worker->task);
+               }
+       }
+
+       if (--idle_rebind.cnt) {
+               spin_unlock_irq(&gcwq->lock);
+               wait_for_completion(&idle_rebind.done);
+               spin_lock_irq(&gcwq->lock);
+               /* busy ones might have become idle while waiting, retry */
+               goto retry;
+       }
+
+       /* all idle workers are rebound, rebind busy workers */
+       for_each_busy_worker(worker, i, pos, gcwq) {
+               unsigned long worker_flags = worker->flags;
+               struct work_struct *rebind_work = &worker->rebind_work;
+               struct workqueue_struct *wq;
+
+               /* morph UNBOUND to REBIND atomically */
+               worker_flags &= ~WORKER_UNBOUND;
+               worker_flags |= WORKER_REBIND;
+               ACCESS_ONCE(worker->flags) = worker_flags;
+
+               if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
+                                    work_data_bits(rebind_work)))
+                       continue;
+
+               debug_work_activate(rebind_work);
+
+               /*
+                * wq doesn't really matter but let's keep @worker->pool
+                * and @cwq->pool consistent for sanity.
+                */
+               if (worker_pool_pri(worker->pool))
+                       wq = system_highpri_wq;
+               else
+                       wq = system_wq;
+
+               insert_work(get_cwq(gcwq->cpu, wq), rebind_work,
+                       worker->scheduled.next,
+                       work_color_to_flags(WORK_NO_COLOR));
+       }
+
+       /*
+        * At this point, each pool is guaranteed to have at least one idle
+        * worker and all idle workers are waiting for WORKER_REBIND to
+        * clear.  Release management before releasing idle workers;
+        * otherwise, they can all go become busy as we're holding the
+        * manager_mutexes, which can lead to deadlock as we don't actually
+        * create new workers.
+        */
+       gcwq_release_management(gcwq);
+
+       /*
+        * Clear %WORKER_REBIND and release.  Clearing it from this foreign
+        * context is safe because these workers are still guaranteed to be
+        * idle.
+        *
+        * We need to make sure all idle workers passed WORKER_REBIND wait
+        * in idle_worker_rebind() before returning; otherwise, workers can
+        * get stuck at the wait if hotplug cycle repeats.
+        */
+       idle_rebind.cnt = 1;
+       INIT_COMPLETION(idle_rebind.done);
+
+       for_each_worker_pool(pool, gcwq) {
+               WARN_ON_ONCE(list_empty(&pool->idle_list));
+               list_for_each_entry(worker, &pool->idle_list, entry) {
+                       worker->flags &= ~WORKER_REBIND;
+                       idle_rebind.cnt++;
+               }
+       }
+
+       wake_up_all(&gcwq->rebind_hold);
+
+       if (--idle_rebind.cnt) {
+               spin_unlock_irq(&gcwq->lock);
+               wait_for_completion(&idle_rebind.done);
+       } else {
+               spin_unlock_irq(&gcwq->lock);
+       }
+}
+
 static void gcwq_unbind_fn(struct work_struct *work)
 {
        struct global_cwq *gcwq = get_gcwq(smp_processor_id());