workqueue: ROGUE workers are UNBOUND workers

Currently, WORKER_UNBOUND is used to mark workers for the unbound
global_cwq and WORKER_ROGUE is used to mark workers for disassociated
per-cpu global_cwqs.  Both are used to make the marked worker skip
concurrency management and the only place they make any difference is
in worker_enter_idle() where WORKER_ROGUE is used to skip scheduling
idle timer, which can easily be replaced with trustee state testing.

This patch replaces WORKER_ROGUE with WORKER_UNBOUND and drops
WORKER_ROGUE.  This is to prepare for removing trustee and handling
disassociated global_cwqs as unbound.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>

1 files changed, 21 insertions, 25 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 1405fb98c0b1..af512927c607 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -58,13 +58,12 @@ enum {
         WORKER_DIE              = 1 << 1,       /* die die die */
         WORKER_IDLE             = 1 << 2,       /* is idle */
         WORKER_PREP             = 1 << 3,       /* preparing to run works */
-        WORKER_ROGUE            = 1 << 4,       /* not bound to any cpu */
         WORKER_REBIND           = 1 << 5,       /* mom is home, come back */
         WORKER_CPU_INTENSIVE    = 1 << 6,       /* cpu intensive */
         WORKER_UNBOUND          = 1 << 7,       /* worker is unbound */
 
-        WORKER_NOT_RUNNING      = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND |
-                                  WORKER_CPU_INTENSIVE | WORKER_UNBOUND,
+        WORKER_NOT_RUNNING      = WORKER_PREP | WORKER_REBIND | WORKER_UNBOUND |
+                                  WORKER_CPU_INTENSIVE,
 
         /* gcwq->trustee_state */
         TRUSTEE_START           = 0,            /* start */
@@ -1198,7 +1197,7 @@ static void worker_enter_idle(struct worker *worker)
         /* idle_list is LIFO */
         list_add(&worker->entry, &pool->idle_list);
 
-        if (likely(!(worker->flags & WORKER_ROGUE))) {
+        if (likely(gcwq->trustee_state != TRUSTEE_DONE)) {
                 if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
                         mod_timer(&pool->idle_timer,
                                   jiffies + IDLE_WORKER_TIMEOUT);
@@ -1207,7 +1206,7 @@ static void worker_enter_idle(struct worker *worker)
 
         /*
          * Sanity check nr_running.  Because trustee releases gcwq->lock
-         * between setting %WORKER_ROGUE and zapping nr_running, the
+         * between setting %WORKER_UNBOUND and zapping nr_running, the
          * warning may trigger spuriously.  Check iff trustee is idle.
          */
         WARN_ON_ONCE(gcwq->trustee_state == TRUSTEE_DONE &&
@@ -1301,10 +1300,10 @@ __acquires(&gcwq->lock)
 }
 
 /*
- * Function for worker->rebind_work used to rebind rogue busy workers
- * to the associated cpu which is coming back online.  This is
- * scheduled by cpu up but can race with other cpu hotplug operations
- * and may be executed twice without intervening cpu down.
+ * Function for worker->rebind_work used to rebind unbound busy workers to
+ * the associated cpu which is coming back online.  This is scheduled by
+ * cpu up but can race with other cpu hotplug operations and may be
+ * executed twice without intervening cpu down.
  */
 static void worker_rebind_fn(struct work_struct *work)
 {
@@ -1385,9 +1384,8 @@ static struct worker *create_worker(struct worker_pool *pool, bool bind)
                 set_user_nice(worker->task, HIGHPRI_NICE_LEVEL);
 
         /*
-         * A rogue worker will become a regular one if CPU comes
-         * online later on.  Make sure every worker has
-         * PF_THREAD_BOUND set.
+         * An unbound worker will become a regular one if CPU comes online
+         * later on.  Make sure every worker has PF_THREAD_BOUND set.
          */
         if (bind && !on_unbound_cpu)
                 kthread_bind(worker->task, gcwq->cpu);
@@ -3215,11 +3213,10 @@ EXPORT_SYMBOL_GPL(work_busy);
  * gcwqs serve mix of short, long and very long running works making
  * blocked draining impractical.
  *
- * This is solved by allowing a gcwq to be detached from CPU, running
- * it with unbound (rogue) workers and allowing it to be reattached
- * later if the cpu comes back online.  A separate thread is created
- * to govern a gcwq in such state and is called the trustee of the
- * gcwq.
+ * This is solved by allowing a gcwq to be detached from CPU, running it
+ * with unbound workers and allowing it to be reattached later if the cpu
+ * comes back online.  A separate thread is created to govern a gcwq in
+ * such state and is called the trustee of the gcwq.
  *
  * Trustee states and their descriptions.
  *
@@ -3359,19 +3356,18 @@ static int __cpuinit trustee_thread(void *__gcwq)
                 pool->flags |= POOL_MANAGING_WORKERS;
 
                 list_for_each_entry(worker, &pool->idle_list, entry)
-                        worker->flags |= WORKER_ROGUE;
+                        worker->flags |= WORKER_UNBOUND;
         }
 
         for_each_busy_worker(worker, i, pos, gcwq)
-                worker->flags |= WORKER_ROGUE;
+                worker->flags |= WORKER_UNBOUND;
 
         gcwq->flags |= GCWQ_DISASSOCIATED;
 
         /*
-         * Call schedule() so that we cross rq->lock and thus can
-         * guarantee sched callbacks see the rogue flag.  This is
-         * necessary as scheduler callbacks may be invoked from other
-         * cpus.
+         * Call schedule() so that we cross rq->lock and thus can guarantee
+         * sched callbacks see the unbound flag.  This is necessary as
+         * scheduler callbacks may be invoked from other cpus.
          */
         spin_unlock_irq(&gcwq->lock);
         schedule();
@@ -3439,7 +3435,7 @@ static int __cpuinit trustee_thread(void *__gcwq)
                                 worker = create_worker(pool, false);
                                 spin_lock_irq(&gcwq->lock);
                                 if (worker) {
-                                        worker->flags |= WORKER_ROGUE;
+                                        worker->flags |= WORKER_UNBOUND;
                                         start_worker(worker);
                                 }
                         }
@@ -3488,7 +3484,7 @@ static int __cpuinit trustee_thread(void *__gcwq)
                  * rebinding is scheduled.
                  */
                 worker->flags |= WORKER_REBIND;
-                worker->flags &= ~WORKER_ROGUE;
+                worker->flags &= ~WORKER_UNBOUND;
 
                 /* queue rebind_work, wq doesn't matter, use the default one */
                 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,