Merge tag 'wq-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue update from Tejun Heo:
 "Just one commit to improve lockdep annotation for work_on_cpu() to
  avoid spurious warnings"

* tag 'wq-for-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Provide one lock class key per work_on_cpu() callsite

2 files changed, 51 insertions, 15 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 1c1d06804d45..24b1e5070f4d 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -274,18 +274,16 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
  * to generate better code.
  */
 #ifdef CONFIG_LOCKDEP
-#define __INIT_WORK(_work, _func, _onstack)				\
+#define __INIT_WORK_KEY(_work, _func, _onstack, _key)			\
 	do {								\
-		static struct lock_class_key __key;			\
-									\
 		__init_work((_work), _onstack);				\
 		(_work)->data = (atomic_long_t) WORK_DATA_INIT();	\
-		lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, &__key, 0); \
+		lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, (_key), 0); \
 		INIT_LIST_HEAD(&(_work)->entry);			\
 		(_work)->func = (_func);				\
 	} while (0)
 #else
-#define __INIT_WORK(_work, _func, _onstack)				\
+#define __INIT_WORK_KEY(_work, _func, _onstack, _key)			\
 	do {								\
 		__init_work((_work), _onstack);				\
 		(_work)->data = (atomic_long_t) WORK_DATA_INIT();	\
@@ -294,12 +292,22 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
 	} while (0)
 #endif
 
+#define __INIT_WORK(_work, _func, _onstack)				\
+	do {								\
+		static __maybe_unused struct lock_class_key __key;	\
+									\
+		__INIT_WORK_KEY(_work, _func, _onstack, &__key);	\
+	} while (0)
+
 #define INIT_WORK(_work, _func)						\
 	__INIT_WORK((_work), (_func), 0)
 
 #define INIT_WORK_ONSTACK(_work, _func)					\
 	__INIT_WORK((_work), (_func), 1)
 
+#define INIT_WORK_ONSTACK_KEY(_work, _func, _key)			\
+	__INIT_WORK_KEY((_work), (_func), 1, _key)
+
 #define __INIT_DELAYED_WORK(_work, _func, _tflags)			\
 	do {								\
 		INIT_WORK(&(_work)->work, (_func));			\
@@ -693,8 +701,32 @@ static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
 	return fn(arg);
 }
 #else
-long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
-long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg);
+long work_on_cpu_key(int cpu, long (*fn)(void *),
+		     void *arg, struct lock_class_key *key);
+/*
+ * A new key is defined for each caller to make sure the work
+ * associated with the function doesn't share its locking class.
+ */
+#define work_on_cpu(_cpu, _fn, _arg)			\
+({							\
+	static struct lock_class_key __key;		\
+							\
+	work_on_cpu_key(_cpu, _fn, _arg, &__key);	\
+})
+
+long work_on_cpu_safe_key(int cpu, long (*fn)(void *),
+			  void *arg, struct lock_class_key *key);
+
+/*
+ * A new key is defined for each caller to make sure the work
+ * associated with the function doesn't share its locking class.
+ */
+#define work_on_cpu_safe(_cpu, _fn, _arg)		\
+({							\
+	static struct lock_class_key __key;		\
+							\
+	work_on_cpu_safe_key(_cpu, _fn, _arg, &__key);	\
+})
 #endif /* CONFIG_SMP */
 
 #ifdef CONFIG_FREEZER
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index a3522b70218d..0f682da96e1c 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5622,50 +5622,54 @@ static void work_for_cpu_fn(struct work_struct *work)
 }
 
 /**
- * work_on_cpu - run a function in thread context on a particular cpu
+ * work_on_cpu_key - run a function in thread context on a particular cpu
  * @cpu: the cpu to run on
  * @fn: the function to run
  * @arg: the function arg
+ * @key: The lock class key for lock debugging purposes
  *
  * It is up to the caller to ensure that the cpu doesn't go offline.
  * The caller must not hold any locks which would prevent @fn from completing.
  *
  * Return: The value @fn returns.
  */
-long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
+long work_on_cpu_key(int cpu, long (*fn)(void *),
+		     void *arg, struct lock_class_key *key)
 {
 	struct work_for_cpu wfc = { .fn = fn, .arg = arg };
 
-	INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
+	INIT_WORK_ONSTACK_KEY(&wfc.work, work_for_cpu_fn, key);
 	schedule_work_on(cpu, &wfc.work);
 	flush_work(&wfc.work);
 	destroy_work_on_stack(&wfc.work);
 	return wfc.ret;
 }
-EXPORT_SYMBOL_GPL(work_on_cpu);
+EXPORT_SYMBOL_GPL(work_on_cpu_key);
 
 /**
- * work_on_cpu_safe - run a function in thread context on a particular cpu
+ * work_on_cpu_safe_key - run a function in thread context on a particular cpu
  * @cpu: the cpu to run on
  * @fn:  the function to run
  * @arg: the function argument
+ * @key: The lock class key for lock debugging purposes
  *
  * Disables CPU hotplug and calls work_on_cpu(). The caller must not hold
  * any locks which would prevent @fn from completing.
  *
  * Return: The value @fn returns.
  */
-long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
+long work_on_cpu_safe_key(int cpu, long (*fn)(void *),
+			  void *arg, struct lock_class_key *key)
 {
 	long ret = -ENODEV;
 
 	cpus_read_lock();
 	if (cpu_online(cpu))
-		ret = work_on_cpu(cpu, fn, arg);
+		ret = work_on_cpu_key(cpu, fn, arg, key);
 	cpus_read_unlock();
 	return ret;
 }
-EXPORT_SYMBOL_GPL(work_on_cpu_safe);
+EXPORT_SYMBOL_GPL(work_on_cpu_safe_key);
 #endif /* CONFIG_SMP */
 
 #ifdef CONFIG_FREEZER