locking/percpu-rwsem, lockdep: Make percpu-rwsem use its own lockdep_map

As preparation for replacing the embedded rwsem, give percpu-rwsem its
own lockdep_map.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20200131151539.927625541@infradead.org

kernel/cpu.c

@@ -331,12 +331,12 @@ void lockdep_assert_cpus_held(void)
 
 static void lockdep_acquire_cpus_lock(void)
 {
-	rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_);
+	rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_);
 }
 
 static void lockdep_release_cpus_lock(void)
 {
-	rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, _THIS_IP_);
+	rwsem_release(&cpu_hotplug_lock.dep_map, _THIS_IP_);
 }
 
 /*

kernel/locking/percpu-rwsem.c

@@ -11,7 +11,7 @@
 #include "rwsem.h"
 
 int __percpu_init_rwsem(struct percpu_rw_semaphore *sem,
-			const char *name, struct lock_class_key *rwsem_key)
+			const char *name, struct lock_class_key *key)
 {
 	sem->read_count = alloc_percpu(int);
 	if (unlikely(!sem->read_count))
@@ -19,9 +19,13 @@ int __percpu_init_rwsem(struct percpu_rw_semaphore *sem,
 
 	/* ->rw_sem represents the whole percpu_rw_semaphore for lockdep */
 	rcu_sync_init(&sem->rss);
-	__init_rwsem(&sem->rw_sem, name, rwsem_key);
+	init_rwsem(&sem->rw_sem);
 	rcuwait_init(&sem->writer);
 	sem->readers_block = 0;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	debug_check_no_locks_freed((void *)sem, sizeof(*sem));
+	lockdep_init_map(&sem->dep_map, name, key, 0);
+#endif
 	return 0;
 }
 EXPORT_SYMBOL_GPL(__percpu_init_rwsem);
@@ -142,10 +146,12 @@ static bool readers_active_check(struct percpu_rw_semaphore *sem)
 
 void percpu_down_write(struct percpu_rw_semaphore *sem)
 {
+	rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
+
 	/* Notify readers to take the slow path. */
 	rcu_sync_enter(&sem->rss);
 
-	down_write(&sem->rw_sem);
+	__down_write(&sem->rw_sem);
 
 	/*
 	 * Notify new readers to block; up until now, and thus throughout the
@@ -168,6 +174,8 @@ EXPORT_SYMBOL_GPL(percpu_down_write);
 
 void percpu_up_write(struct percpu_rw_semaphore *sem)
 {
+	rwsem_release(&sem->dep_map, _RET_IP_);
+
 	/*
 	 * Signal the writer is done, no fast path yet.
 	 *
@@ -183,7 +191,7 @@ void percpu_up_write(struct percpu_rw_semaphore *sem)
 	/*
 	 * Release the write lock, this will allow readers back in the game.
 	 */
-	up_write(&sem->rw_sem);
+	__up_write(&sem->rw_sem);
 
 	/*
 	 * Once this completes (at least one RCU-sched grace period hence) the

kernel/locking/rwsem.c

@@ -1383,7 +1383,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
 /*
  * lock for writing
  */
-static inline void __down_write(struct rw_semaphore *sem)
+inline void __down_write(struct rw_semaphore *sem)
 {
 	long tmp = RWSEM_UNLOCKED_VALUE;
 
@@ -1446,7 +1446,7 @@ inline void __up_read(struct rw_semaphore *sem)
 /*
  * unlock after writing
  */
-static inline void __up_write(struct rw_semaphore *sem)
+inline void __up_write(struct rw_semaphore *sem)
 {
 	long tmp;
 

kernel/locking/rwsem.h

@@ -6,5 +6,7 @@
 
 extern void __down_read(struct rw_semaphore *sem);
 extern void __up_read(struct rw_semaphore *sem);
+extern void __down_write(struct rw_semaphore *sem);
+extern void __up_write(struct rw_semaphore *sem);
 
 #endif /* __INTERNAL_RWSEM_H */