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Subject[PATCH 1/5] 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>
---
include/linux/percpu-rwsem.h | 29 +++++++++++++++++++----------
kernel/cpu.c | 4 ++--
kernel/locking/percpu-rwsem.c | 14 +++++++++++---
kernel/locking/rwsem.c | 4 ++--
kernel/locking/rwsem.h | 2 ++
5 files changed, 36 insertions(+), 17 deletions(-)

--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -15,8 +15,17 @@ struct percpu_rw_semaphore {
struct rw_semaphore rw_sem; /* slowpath */
struct rcuwait writer; /* blocked writer */
int readers_block;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ struct lockdep_map dep_map;
+#endif
};

+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#define __PERCPU_RWSEM_DEP_MAP_INIT(lockname) .dep_map = { .name = #lockname },
+#else
+#define __PERCPU_RWSEM_DEP_MAP_INIT(lockname)
+#endif
+
#define __DEFINE_PERCPU_RWSEM(name, is_static) \
static DEFINE_PER_CPU(unsigned int, __percpu_rwsem_rc_##name); \
is_static struct percpu_rw_semaphore name = { \
@@ -24,7 +33,9 @@ is_static struct percpu_rw_semaphore nam
.read_count = &__percpu_rwsem_rc_##name, \
.rw_sem = __RWSEM_INITIALIZER(name.rw_sem), \
.writer = __RCUWAIT_INITIALIZER(name.writer), \
+ __PERCPU_RWSEM_DEP_MAP_INIT(name) \
}
+
#define DEFINE_PERCPU_RWSEM(name) \
__DEFINE_PERCPU_RWSEM(name, /* not static */)
#define DEFINE_STATIC_PERCPU_RWSEM(name) \
@@ -37,7 +48,7 @@ static inline void percpu_down_read(stru
{
might_sleep();

- rwsem_acquire_read(&sem->rw_sem.dep_map, 0, 0, _RET_IP_);
+ rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);

preempt_disable();
/*
@@ -76,13 +87,15 @@ static inline int percpu_down_read_trylo
*/

if (ret)
- rwsem_acquire_read(&sem->rw_sem.dep_map, 0, 1, _RET_IP_);
+ rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);

return ret;
}

static inline void percpu_up_read(struct percpu_rw_semaphore *sem)
{
+ rwsem_release(&sem->dep_map, _RET_IP_);
+
preempt_disable();
/*
* Same as in percpu_down_read().
@@ -92,8 +105,6 @@ static inline void percpu_up_read(struct
else
__percpu_up_read(sem); /* Unconditional memory barrier */
preempt_enable();
-
- rwsem_release(&sem->rw_sem.dep_map, _RET_IP_);
}

extern void percpu_down_write(struct percpu_rw_semaphore *);
@@ -110,15 +121,13 @@ extern void percpu_free_rwsem(struct per
__percpu_init_rwsem(sem, #sem, &rwsem_key); \
})

-#define percpu_rwsem_is_held(sem) lockdep_is_held(&(sem)->rw_sem)
-
-#define percpu_rwsem_assert_held(sem) \
- lockdep_assert_held(&(sem)->rw_sem)
+#define percpu_rwsem_is_held(sem) lockdep_is_held(sem)
+#define percpu_rwsem_assert_held(sem) lockdep_assert_held(sem)

static inline void percpu_rwsem_release(struct percpu_rw_semaphore *sem,
bool read, unsigned long ip)
{
- lock_release(&sem->rw_sem.dep_map, ip);
+ lock_release(&sem->dep_map, ip);
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
if (!read)
atomic_long_set(&sem->rw_sem.owner, RWSEM_OWNER_UNKNOWN);
@@ -128,7 +137,7 @@ static inline void percpu_rwsem_release(
static inline void percpu_rwsem_acquire(struct percpu_rw_semaphore *sem,
bool read, unsigned long ip)
{
- lock_acquire(&sem->rw_sem.dep_map, 0, 1, read, 1, NULL, ip);
+ lock_acquire(&sem->dep_map, 0, 1, read, 1, NULL, ip);
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
if (!read)
atomic_long_set(&sem->rw_sem.owner, (long)current);
--- a/kernel/cpu.c
+++ b/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_);
}

/*
--- a/kernel/locking/percpu-rwsem.c
+++ b/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))
@@ -22,6 +22,10 @@ int __percpu_init_rwsem(struct percpu_rw
__init_rwsem(&sem->rw_sem, name, rwsem_key);
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

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_se
/*
* 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
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -1383,7 +1383,7 @@ static inline int __down_read_trylock(st
/*
* 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_semaphor
/*
* unlock after writing
*/
-static inline void __up_write(struct rw_semaphore *sem)
+inline void __up_write(struct rw_semaphore *sem)
{
long tmp;

--- a/kernel/locking/rwsem.h
+++ b/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 */

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