workqueue: Add interface for user-defined workqueue lockdep map

Add an interface for a user-defined workqueue lockdep map, which is
helpful when multiple workqueues are created for the same purpose. This
also helps avoid leaking lockdep maps on each workqueue creation.

v2:
 - Add alloc_workqueue_lockdep_map (Tejun)
v3:
 - Drop __WQ_USER_OWNED_LOCKDEP (Tejun)
 - static inline alloc_ordered_workqueue_lockdep_map (Tejun)

Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 4eb8f9563136393fccae37b44ee97b2377bb3bc1..8ccbf510880b8afab6334962f9c608b9fc37fab0 100644 (file)
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -507,6 +507,58 @@ void workqueue_softirq_dead(unsigned int cpu);
 __printf(1, 4) struct workqueue_struct *
 alloc_workqueue(const char *fmt, unsigned int flags, int max_active, ...);
 
+#ifdef CONFIG_LOCKDEP
+/**
+ * alloc_workqueue_lockdep_map - allocate a workqueue with user-defined lockdep_map
+ * @fmt: printf format for the name of the workqueue
+ * @flags: WQ_* flags
+ * @max_active: max in-flight work items, 0 for default
+ * @lockdep_map: user-defined lockdep_map
+ * @...: args for @fmt
+ *
+ * Same as alloc_workqueue but with the a user-define lockdep_map. Useful for
+ * workqueues created with the same purpose and to avoid leaking a lockdep_map
+ * on each workqueue creation.
+ *
+ * RETURNS:
+ * Pointer to the allocated workqueue on success, %NULL on failure.
+ */
+__printf(1, 5) struct workqueue_struct *
+alloc_workqueue_lockdep_map(const char *fmt, unsigned int flags, int max_active,
+                           struct lockdep_map *lockdep_map, ...);
+
+/**
+ * alloc_ordered_workqueue_lockdep_map - allocate an ordered workqueue with
+ * user-defined lockdep_map
+ *
+ * @fmt: printf format for the name of the workqueue
+ * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
+ * @lockdep_map: user-defined lockdep_map
+ * @args: args for @fmt
+ *
+ * Same as alloc_ordered_workqueue but with the a user-define lockdep_map.
+ * Useful for workqueues created with the same purpose and to avoid leaking a
+ * lockdep_map on each workqueue creation.
+ *
+ * RETURNS:
+ * Pointer to the allocated workqueue on success, %NULL on failure.
+ */
+__printf(1, 4) static inline struct workqueue_struct *
+alloc_ordered_workqueue_lockdep_map(const char *fmt, unsigned int flags,
+                                   struct lockdep_map *lockdep_map, ...)
+{
+       struct workqueue_struct *wq;
+       va_list args;
+
+       va_start(args, lockdep_map);
+       wq = alloc_workqueue_lockdep_map(fmt, WQ_UNBOUND | __WQ_ORDERED | flags,
+                                        1, lockdep_map, args);
+       va_end(args);
+
+       return wq;
+}
+#endif
+
 /**
  * alloc_ordered_workqueue - allocate an ordered workqueue
  * @fmt: printf format for the name of the workqueue

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 4c8ba5c4229fdc6b58721f8fb9790ca27429d327..7468ba5e2417f00d2fe977f043dbb67d19f1f308 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4775,11 +4775,17 @@ static void wq_init_lockdep(struct workqueue_struct *wq)
 
 static void wq_unregister_lockdep(struct workqueue_struct *wq)
 {
+       if (wq->lockdep_map != &wq->__lockdep_map)
+               return;
+
        lockdep_unregister_key(&wq->key);
 }
 
 static void wq_free_lockdep(struct workqueue_struct *wq)
 {
+       if (wq->lockdep_map != &wq->__lockdep_map)
+               return;
+
        if (wq->lock_name != wq->name)
                kfree(wq->lock_name);
 }
@@ -5756,6 +5762,28 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
 }
 EXPORT_SYMBOL_GPL(alloc_workqueue);
 
+#ifdef CONFIG_LOCKDEP
+__printf(1, 5)
+struct workqueue_struct *
+alloc_workqueue_lockdep_map(const char *fmt, unsigned int flags,
+                           int max_active, struct lockdep_map *lockdep_map, ...)
+{
+       struct workqueue_struct *wq;
+       va_list args;
+
+       va_start(args, lockdep_map);
+       wq = __alloc_workqueue(fmt, flags, max_active, args);
+       va_end(args);
+       if (!wq)
+               return NULL;
+
+       wq->lockdep_map = lockdep_map;
+
+       return wq;
+}
+EXPORT_SYMBOL_GPL(alloc_workqueue_lockdep_map);
+#endif
+
 static bool pwq_busy(struct pool_workqueue *pwq)
 {
        int i;