Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: use zalloc_cpumask_var() for gcwq->mayday_mask
  workqueue: fix GCWQ_DISASSOCIATED initialization
  workqueue: Add a workqueue chapter to the tracepoint docbook
  workqueue: fix cwq->nr_active underflow
  workqueue: improve destroy_workqueue() debuggability
  workqueue: mark lock acquisition on worker_maybe_bind_and_lock()
  workqueue: annotate lock context change
  workqueue: free rescuer on destroy_workqueue

1 files changed, 38 insertions, 15 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 8bd600c020e5..727f24e563ae 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -90,7 +90,8 @@ enum {
 /*
  * Structure fields follow one of the following exclusion rules.
  *
- * I: Set during initialization and read-only afterwards.
+ * I: Modifiable by initialization/destruction paths and read-only for
+ *    everyone else.
  *
  * P: Preemption protected.  Disabling preemption is enough and should
  *    only be modified and accessed from the local cpu.
@@ -198,7 +199,7 @@ typedef cpumask_var_t mayday_mask_t;
         cpumask_test_and_set_cpu((cpu), (mask))
 #define mayday_clear_cpu(cpu, mask)             cpumask_clear_cpu((cpu), (mask))
 #define for_each_mayday_cpu(cpu, mask)          for_each_cpu((cpu), (mask))
-#define alloc_mayday_mask(maskp, gfp)           alloc_cpumask_var((maskp), (gfp))
+#define alloc_mayday_mask(maskp, gfp)           zalloc_cpumask_var((maskp), (gfp))
 #define free_mayday_mask(mask)                  free_cpumask_var((mask))
 #else
 typedef unsigned long mayday_mask_t;
@@ -943,10 +944,14 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
         struct global_cwq *gcwq;
         struct cpu_workqueue_struct *cwq;
         struct list_head *worklist;
+        unsigned int work_flags;
         unsigned long flags;
 
         debug_work_activate(work);
 
+        if (WARN_ON_ONCE(wq->flags & WQ_DYING))
+                return;
+
         /* determine gcwq to use */
         if (!(wq->flags & WQ_UNBOUND)) {
                 struct global_cwq *last_gcwq;
@@ -989,14 +994,17 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
         BUG_ON(!list_empty(&work->entry));
 
         cwq->nr_in_flight[cwq->work_color]++;
+        work_flags = work_color_to_flags(cwq->work_color);
 
         if (likely(cwq->nr_active < cwq->max_active)) {
                 cwq->nr_active++;
                 worklist = gcwq_determine_ins_pos(gcwq, cwq);
-        } else
+        } else {
+                work_flags |= WORK_STRUCT_DELAYED;
                 worklist = &cwq->delayed_works;
+        }
 
-        insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color));
+        insert_work(cwq, work, worklist, work_flags);
 
         spin_unlock_irqrestore(&gcwq->lock, flags);
 }
@@ -1215,6 +1223,7 @@ static void worker_leave_idle(struct worker *worker)
  * bound), %false if offline.
  */
 static bool worker_maybe_bind_and_lock(struct worker *worker)
+__acquires(&gcwq->lock)
 {
         struct global_cwq *gcwq = worker->gcwq;
         struct task_struct *task = worker->task;
@@ -1488,6 +1497,8 @@ static void gcwq_mayday_timeout(unsigned long __gcwq)
  * otherwise.
  */
 static bool maybe_create_worker(struct global_cwq *gcwq)
+__releases(&gcwq->lock)
+__acquires(&gcwq->lock)
 {
         if (!need_to_create_worker(gcwq))
                 return false;
@@ -1662,6 +1673,7 @@ static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
         struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
 
         move_linked_works(work, pos, NULL);
+        __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
         cwq->nr_active++;
 }
 
@@ -1669,6 +1681,7 @@ static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
  * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
  * @cwq: cwq of interest
  * @color: color of work which left the queue
+ * @delayed: for a delayed work
  *
  * A work either has completed or is removed from pending queue,
  * decrement nr_in_flight of its cwq and handle workqueue flushing.
@@ -1676,19 +1689,22 @@ static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
  * CONTEXT:
  * spin_lock_irq(gcwq->lock).
  */
-static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
+static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
+                                 bool delayed)
 {
         /* ignore uncolored works */
         if (color == WORK_NO_COLOR)
                 return;
 
         cwq->nr_in_flight[color]--;
-        cwq->nr_active--;
 
-        if (!list_empty(&cwq->delayed_works)) {
-                /* one down, submit a delayed one */
-                if (cwq->nr_active < cwq->max_active)
-                        cwq_activate_first_delayed(cwq);
+        if (!delayed) {
+                cwq->nr_active--;
+                if (!list_empty(&cwq->delayed_works)) {
+                        /* one down, submit a delayed one */
+                        if (cwq->nr_active < cwq->max_active)
+                                cwq_activate_first_delayed(cwq);
+                }
         }
 
         /* is flush in progress and are we at the flushing tip? */
@@ -1725,6 +1741,8 @@ static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
  * spin_lock_irq(gcwq->lock) which is released and regrabbed.
  */
 static void process_one_work(struct worker *worker, struct work_struct *work)
+__releases(&gcwq->lock)
+__acquires(&gcwq->lock)
 {
         struct cpu_workqueue_struct *cwq = get_work_cwq(work);
         struct global_cwq *gcwq = cwq->gcwq;
@@ -1823,7 +1841,7 @@ static void process_one_work(struct worker *worker, struct work_struct *work)
         hlist_del_init(&worker->hentry);
         worker->current_work = NULL;
         worker->current_cwq = NULL;
-        cwq_dec_nr_in_flight(cwq, work_color);
+        cwq_dec_nr_in_flight(cwq, work_color, false);
 }
 
 /**
@@ -2388,7 +2406,8 @@ static int try_to_grab_pending(struct work_struct *work)
                         debug_work_deactivate(work);
                         list_del_init(&work->entry);
                         cwq_dec_nr_in_flight(get_work_cwq(work),
-                                             get_work_color(work));
+                                get_work_color(work),
+                                *work_data_bits(work) & WORK_STRUCT_DELAYED);
                         ret = 1;
                 }
         }
@@ -2791,7 +2810,6 @@ struct workqueue_struct *__alloc_workqueue_key(const char *name,
                 if (IS_ERR(rescuer->task))
                         goto err;
 
-                wq->rescuer = rescuer;
                 rescuer->task->flags |= PF_THREAD_BOUND;
                 wake_up_process(rescuer->task);
         }
@@ -2833,6 +2851,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
 {
         unsigned int cpu;
 
+        wq->flags |= WQ_DYING;
         flush_workqueue(wq);
 
         /*
@@ -2857,6 +2876,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
         if (wq->flags & WQ_RESCUER) {
                 kthread_stop(wq->rescuer->task);
                 free_mayday_mask(wq->mayday_mask);
+                kfree(wq->rescuer);
         }
 
         free_cwqs(wq);
@@ -3239,6 +3259,8 @@ static int __cpuinit trustee_thread(void *__gcwq)
  * multiple times.  To be used by cpu_callback.
  */
 static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state)
+__releases(&gcwq->lock)
+__acquires(&gcwq->lock)
 {
         if (!(gcwq->trustee_state == state ||
               gcwq->trustee_state == TRUSTEE_DONE)) {
@@ -3545,8 +3567,7 @@ static int __init init_workqueues(void)
                 spin_lock_init(&gcwq->lock);
                 INIT_LIST_HEAD(&gcwq->worklist);
                 gcwq->cpu = cpu;
-                if (cpu == WORK_CPU_UNBOUND)
-                        gcwq->flags |= GCWQ_DISASSOCIATED;
+                gcwq->flags |= GCWQ_DISASSOCIATED;
 
                 INIT_LIST_HEAD(&gcwq->idle_list);
                 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
@@ -3570,6 +3591,8 @@ static int __init init_workqueues(void)
                 struct global_cwq *gcwq = get_gcwq(cpu);
                 struct worker *worker;
 
+                if (cpu != WORK_CPU_UNBOUND)
+                        gcwq->flags &= ~GCWQ_DISASSOCIATED;
                 worker = create_worker(gcwq, true);
                 BUG_ON(!worker);
                 spin_lock_irq(&gcwq->lock);