[PATCH RT 5/8] rt: rwsem/rwlock: lockdep annotations

Steven Rostedt
2012-10-12T01:22:16Z

[-- Attachment #1: 0005-rt-rwsem-rwlock-lockdep-annotations.patch --]
[-- Type: text/plain, Size: 3249 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

rwlocks and rwsems on RT do not allow multiple readers. Annotate the
lockdep acquire functions accordingly.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/rt.c | 46 +++++++++++++++++++++++++---------------------
1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/kernel/rt.c b/kernel/rt.c
index 092d6b3..aa10504 100644
--- a/kernel/rt.c
+++ b/kernel/rt.c
@@ -216,15 +216,17 @@ int __lockfunc rt_read_trylock(rwlock_t *rwlock)
* write locked.
*/
migrate_disable();
- if (rt_mutex_owner(lock) != current)
+ if (rt_mutex_owner(lock) != current) {
ret = rt_mutex_trylock(lock);
- else if (!rwlock->read_depth)
+ if (ret)
+ rwlock_acquire(&rwlock->dep_map, 0, 1, _RET_IP_);
+ } else if (!rwlock->read_depth) {
ret = 0;
+ }

- if (ret) {
+ if (ret)
rwlock->read_depth++;
- rwlock_acquire_read(&rwlock->dep_map, 0, 1, _RET_IP_);
- } else
+ else
migrate_enable();

return ret;
@@ -242,13 +244,13 @@ void __lockfunc rt_read_lock(rwlock_t *rwlock)
{
struct rt_mutex *lock = &rwlock->lock;

- rwlock_acquire_read(&rwlock->dep_map, 0, 0, _RET_IP_);
-
/*
* recursive read locks succeed when current owns the lock
*/
- if (rt_mutex_owner(lock) != current)
+ if (rt_mutex_owner(lock) != current) {
+ rwlock_acquire(&rwlock->dep_map, 0, 0, _RET_IP_);
__rt_spin_lock(lock);
+ }
rwlock->read_depth++;
}

@@ -264,11 +266,11 @@ EXPORT_SYMBOL(rt_write_unlock);

void __lockfunc rt_read_unlock(rwlock_t *rwlock)
{
- rwlock_release(&rwlock->dep_map, 1, _RET_IP_);
-
/* Release the lock only when read_depth is down to 0 */
- if (--rwlock->read_depth == 0)
+ if (--rwlock->read_depth == 0) {
+ rwlock_release(&rwlock->dep_map, 1, _RET_IP_);
__rt_spin_unlock(&rwlock->lock);
+ }
}
EXPORT_SYMBOL(rt_read_unlock);

@@ -315,9 +317,10 @@ EXPORT_SYMBOL(rt_up_write);

void rt_up_read(struct rw_semaphore *rwsem)
{
- rwsem_release(&rwsem->dep_map, 1, _RET_IP_);
- if (--rwsem->read_depth == 0)
+ if (--rwsem->read_depth == 0) {
+ rwsem_release(&rwsem->dep_map, 1, _RET_IP_);
rt_mutex_unlock(&rwsem->lock);
+ }
}
EXPORT_SYMBOL(rt_up_read);

@@ -366,15 +369,16 @@ int rt_down_read_trylock(struct rw_semaphore *rwsem)
* but not when read_depth == 0 which means that the rwsem is
* write locked.
*/
- if (rt_mutex_owner(lock) != current)
+ if (rt_mutex_owner(lock) != current) {
ret = rt_mutex_trylock(&rwsem->lock);
- else if (!rwsem->read_depth)
+ if (ret)
+ rwsem_acquire(&rwsem->dep_map, 0, 1, _RET_IP_);
+ } else if (!rwsem->read_depth) {
ret = 0;
+ }

- if (ret) {
+ if (ret)
rwsem->read_depth++;
- rwsem_acquire(&rwsem->dep_map, 0, 1, _RET_IP_);
- }
return ret;
}
EXPORT_SYMBOL(rt_down_read_trylock);
@@ -383,10 +387,10 @@ static void __rt_down_read(struct rw_semaphore *rwsem, int subclass)
{
struct rt_mutex *lock = &rwsem->lock;

- rwsem_acquire_read(&rwsem->dep_map, subclass, 0, _RET_IP_);
-
- if (rt_mutex_owner(lock) != current)
+ if (rt_mutex_owner(lock) != current) {
+ rwsem_acquire(&rwsem->dep_map, subclass, 0, _RET_IP_);
rt_mutex_lock(&rwsem->lock);
+ }
rwsem->read_depth++;
}

--
1.7.10.4