locking/local_lock: Add missing owner initialization

If CONFIG_DEBUG_LOCK_ALLOC=y is enabled then local_lock_t has an 'owner'
member which is checked for consistency, but nothing initialized it to
zero explicitly.

The static initializer does so implicit, and the run time allocated per CPU
storage is usually zero initialized as well, but relying on that is not
really good practice.

Fixes: 91710728 ("locking: Introduce local_lock()")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211301.969975279@linutronix.de

include/linux/local_lock_internal.h

@@ -14,29 +14,14 @@ typedef struct {
 } local_lock_t;
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define LL_DEP_MAP_INIT(lockname)			\
+# define LOCAL_LOCK_DEBUG_INIT(lockname)		\
 	.dep_map = {					\
 		.name = #lockname,			\
 		.wait_type_inner = LD_WAIT_CONFIG,	\
-		.lock_type = LD_LOCK_PERCPU,			\
-	}
-#else
-# define LL_DEP_MAP_INIT(lockname)
-#endif
-
-#define INIT_LOCAL_LOCK(lockname)	{ LL_DEP_MAP_INIT(lockname) }
-
-#define __local_lock_init(lock)					\
-do {								\
-	static struct lock_class_key __key;			\
-								\
-	debug_check_no_locks_freed((void *)lock, sizeof(*lock));\
-	lockdep_init_map_type(&(lock)->dep_map, #lock, &__key, 0, \
-			      LD_WAIT_CONFIG, LD_WAIT_INV,	\
-			      LD_LOCK_PERCPU);			\
-} while (0)
+		.lock_type = LD_LOCK_PERCPU,		\
+	},						\
+	.owner = NULL,
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
 static inline void local_lock_acquire(local_lock_t *l)
 {
 	lock_map_acquire(&l->dep_map);
@@ -51,11 +36,30 @@ static inline void local_lock_release(local_lock_t *l)
 	lock_map_release(&l->dep_map);
 }
 
+static inline void local_lock_debug_init(local_lock_t *l)
+{
+	l->owner = NULL;
+}
 #else /* CONFIG_DEBUG_LOCK_ALLOC */
+# define LOCAL_LOCK_DEBUG_INIT(lockname)
 static inline void local_lock_acquire(local_lock_t *l) { }
 static inline void local_lock_release(local_lock_t *l) { }
+static inline void local_lock_debug_init(local_lock_t *l) { }
 #endif /* !CONFIG_DEBUG_LOCK_ALLOC */
 
+#define INIT_LOCAL_LOCK(lockname)	{ LOCAL_LOCK_DEBUG_INIT(lockname) }
+
+#define __local_lock_init(lock)					\
+do {								\
+	static struct lock_class_key __key;			\
+								\
+	debug_check_no_locks_freed((void *)lock, sizeof(*lock));\
+	lockdep_init_map_type(&(lock)->dep_map, #lock, &__key,  \
+			      0, LD_WAIT_CONFIG, LD_WAIT_INV,	\
+			      LD_LOCK_PERCPU);			\
+	local_lock_debug_init(lock);				\
+} while (0)
+
 #define __local_lock(lock)					\
 	do {							\
 		preempt_disable();				\