workqueue: rename wq->flush_mutex to wq->mutex

Currently pwq->flush_mutex protects many fields of a workqueue
including, especially, the pwqs list.  We're going to expand this
mutex to protect most of a workqueue and eventually replace pwq_lock,
which will make locking simpler and easier to understand.

Drop the "flush_" prefix in preparation.

This patch is pure rename.

tj: Rebased on top of the current dev branch.  Updated description.
    Use WQ: and WR: instead of Q: and QR: for synchronization labels.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 064157eac4c8fd7eb3c5d729cb1708586856bccb..d448edae35131e9ee6865a0da8b8d754a3a9debe 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -118,8 +118,6 @@ enum {
  *    cpu or grabbing pool->lock is enough for read access.  If
  *    POOL_DISASSOCIATED is set, it's identical to L.
  *
- * F: wq->flush_mutex protected.
- *
  * MG: pool->manager_mutex and pool->lock protected.  Writes require both
  *     locks.  Reads can happen under either lock.
  *
@@ -129,8 +127,10 @@ enum {
  *
  * PW: pwq_lock protected.
  *
- * FR: wq->flush_mutex and pwq_lock protected for writes.  Sched-RCU
- *     protected for reads.
+ * WQ: wq->mutex protected.
+ *
+ * WR: wq->mutex and pwq_lock protected for writes.  Sched-RCU protected
+ *     for reads.
  *
  * MD: wq_mayday_lock protected.
  */
@@ -197,7 +197,7 @@ struct pool_workqueue {
        int                     nr_active;      /* L: nr of active works */
        int                     max_active;     /* L: max active works */
        struct list_head        delayed_works;  /* L: delayed works */
-       struct list_head        pwqs_node;      /* FR: node on wq->pwqs */
+       struct list_head        pwqs_node;      /* WR: node on wq->pwqs */
        struct list_head        mayday_node;    /* MD: node on wq->maydays */
 
        /*
@@ -214,8 +214,8 @@ struct pool_workqueue {
  * Structure used to wait for workqueue flush.
  */
 struct wq_flusher {
-       struct list_head        list;           /* F: list of flushers */
-       int                     flush_color;    /* F: flush color waiting for */
+       struct list_head        list;           /* WQ: list of flushers */
+       int                     flush_color;    /* WQ: flush color waiting for */
        struct completion       done;           /* flush completion */
 };
 
@@ -228,16 +228,16 @@ struct wq_device;
 struct workqueue_struct {
        unsigned int            flags;          /* PL: WQ_* flags */
        struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwq's */
-       struct list_head        pwqs;           /* FR: all pwqs of this wq */
+       struct list_head        pwqs;           /* WR: all pwqs of this wq */
        struct list_head        list;           /* PL: list of all workqueues */
 
-       struct mutex            flush_mutex;    /* protects wq flushing */
-       int                     work_color;     /* F: current work color */
-       int                     flush_color;    /* F: current flush color */
+       struct mutex            mutex;          /* protects this wq */
+       int                     work_color;     /* WQ: current work color */
+       int                     flush_color;    /* WQ: current flush color */
        atomic_t                nr_pwqs_to_flush; /* flush in progress */
-       struct wq_flusher       *first_flusher; /* F: first flusher */
-       struct list_head        flusher_queue;  /* F: flush waiters */
-       struct list_head        flusher_overflow; /* F: flush overflow list */
+       struct wq_flusher       *first_flusher; /* WQ: first flusher */
+       struct list_head        flusher_queue;  /* WQ: flush waiters */
+       struct list_head        flusher_overflow; /* WQ: flush overflow list */
 
        struct list_head        maydays;        /* MD: pwqs requesting rescue */
        struct worker           *rescuer;       /* I: rescue worker */
@@ -2460,7 +2460,7 @@ static void insert_wq_barrier(struct pool_workqueue *pwq,
  * advanced to @work_color.
  *
  * CONTEXT:
- * mutex_lock(wq->flush_mutex).
+ * mutex_lock(wq->mutex).
  *
  * RETURNS:
  * %true if @flush_color >= 0 and there's something to flush.  %false
@@ -2529,7 +2529,7 @@ void flush_workqueue(struct workqueue_struct *wq)
        lock_map_acquire(&wq->lockdep_map);
        lock_map_release(&wq->lockdep_map);
 
-       mutex_lock(&wq->flush_mutex);
+       mutex_lock(&wq->mutex);
 
        /*
         * Start-to-wait phase
@@ -2574,7 +2574,7 @@ void flush_workqueue(struct workqueue_struct *wq)
                list_add_tail(&this_flusher.list, &wq->flusher_overflow);
        }
 
-       mutex_unlock(&wq->flush_mutex);
+       mutex_unlock(&wq->mutex);
 
        wait_for_completion(&this_flusher.done);
 
@@ -2587,7 +2587,7 @@ void flush_workqueue(struct workqueue_struct *wq)
        if (wq->first_flusher != &this_flusher)
                return;
 
-       mutex_lock(&wq->flush_mutex);
+       mutex_lock(&wq->mutex);
 
        /* we might have raced, check again with mutex held */
        if (wq->first_flusher != &this_flusher)
@@ -2659,7 +2659,7 @@ void flush_workqueue(struct workqueue_struct *wq)
        }
 
 out_unlock:
-       mutex_unlock(&wq->flush_mutex);
+       mutex_unlock(&wq->mutex);
 }
 EXPORT_SYMBOL_GPL(flush_workqueue);
 
@@ -3550,15 +3550,15 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
                return;
 
        /*
-        * Unlink @pwq.  Synchronization against flush_mutex isn't strictly
+        * Unlink @pwq.  Synchronization against wq->mutex isn't strictly
         * necessary on release but do it anyway.  It's easier to verify
         * and consistent with the linking path.
         */
-       mutex_lock(&wq->flush_mutex);
+       mutex_lock(&wq->mutex);
        spin_lock_irq(&pwq_lock);
        list_del_rcu(&pwq->pwqs_node);
        spin_unlock_irq(&pwq_lock);
-       mutex_unlock(&wq->flush_mutex);
+       mutex_unlock(&wq->mutex);
 
        put_unbound_pool(pool);
        call_rcu_sched(&pwq->rcu, rcu_free_pwq);
@@ -3627,12 +3627,12 @@ static void init_and_link_pwq(struct pool_workqueue *pwq,
        INIT_LIST_HEAD(&pwq->mayday_node);
        INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
 
-       mutex_lock(&wq->flush_mutex);
+       mutex_lock(&wq->mutex);
        spin_lock_irq(&pwq_lock);
 
        /*
         * Set the matching work_color.  This is synchronized with
-        * flush_mutex to avoid confusing flush_workqueue().
+        * wq->mutex to avoid confusing flush_workqueue().
         */
        if (p_last_pwq)
                *p_last_pwq = first_pwq(wq);
@@ -3645,7 +3645,7 @@ static void init_and_link_pwq(struct pool_workqueue *pwq,
        list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
 
        spin_unlock_irq(&pwq_lock);
-       mutex_unlock(&wq->flush_mutex);
+       mutex_unlock(&wq->mutex);
 }
 
 /**
@@ -3762,7 +3762,7 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
        /* init wq */
        wq->flags = flags;
        wq->saved_max_active = max_active;
-       mutex_init(&wq->flush_mutex);
+       mutex_init(&wq->mutex);
        atomic_set(&wq->nr_pwqs_to_flush, 0);
        INIT_LIST_HEAD(&wq->pwqs);
        INIT_LIST_HEAD(&wq->flusher_queue);