Revert "workqueue: Provide one lock class key per work_on_cpu() callsite"

This reverts commit f9d3ba62e8 which is
commit 265f3ed077036f053981f5eea0b5b43e7c5b39ff upstream.

It turns the work_on_cpu() function into an #define, which messes with
the systems that were previously depending on that abi symbol.  As this
is a change only for when lockdep is enabled, which is NOT in any
running Android system, it is safe to revert for now.

Bug: 161946584
Change-Id: I5f117cccfb411efb742a4faf1cefcb4826faae15
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

include/linux/workqueue.h

@@ -228,16 +228,18 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
  * to generate better code.
  */
 #ifdef CONFIG_LOCKDEP
-#define __INIT_WORK_KEY(_work, _func, _onstack, _key)			\
+#define __INIT_WORK(_work, _func, _onstack)				\
 	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_KEY(_work, _func, _onstack, _key)			\
+#define __INIT_WORK(_work, _func, _onstack)				\
 	do {								\
 		__init_work((_work), _onstack);				\
 		(_work)->data = (atomic_long_t) WORK_DATA_INIT();	\
@@ -246,22 +248,12 @@ 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));			\
@@ -646,32 +638,8 @@ static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
 	return fn(arg);
 }
 #else
-long work_on_cpu_key(int cpu, long (*fn)(void *),
+long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
-		     void *arg, struct lock_class_key *key);
+long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg);
-/*
- * 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

kernel/workqueue.c

@@ -5217,54 +5217,50 @@ static void work_for_cpu_fn(struct work_struct *work)
 }
 
 /**
- * work_on_cpu_key - run a function in thread context on a particular cpu
+ * work_on_cpu - 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_key(int cpu, long (*fn)(void *),
+long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
-		     void *arg, struct lock_class_key *key)
 {
 	struct work_for_cpu wfc = { .fn = fn, .arg = arg };
 
-	INIT_WORK_ONSTACK_KEY(&wfc.work, work_for_cpu_fn, key);
+	INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
 	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_key);
+EXPORT_SYMBOL_GPL(work_on_cpu);
 
 /**
- * work_on_cpu_safe_key - run a function in thread context on a particular cpu
+ * work_on_cpu_safe - 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_key(int cpu, long (*fn)(void *),
+long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
-			  void *arg, struct lock_class_key *key)
 {
 	long ret = -ENODEV;
 
 	cpus_read_lock();
 	if (cpu_online(cpu))
-		ret = work_on_cpu_key(cpu, fn, arg, key);
+		ret = work_on_cpu(cpu, fn, arg);
 	cpus_read_unlock();
 	return ret;
 }
-EXPORT_SYMBOL_GPL(work_on_cpu_safe_key);
+EXPORT_SYMBOL_GPL(work_on_cpu_safe);
 #endif /* CONFIG_SMP */
 
 #ifdef CONFIG_FREEZER