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locking: Make spinlock_t and rwlock_t a RCU section on RT 

On !RT a locked spinlock_t and rwlock_t disables preemption which
implies a RCU read section. There is code that relies on that behaviour.

Add an explicit RCU read section on RT while a sleeping lock (a lock
which would disables preemption on !RT) acquired.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
This commit is contained in:
Sebastian Andrzej Siewior 2019-11-19 09:25:04 +01:00 committed by Alibek Omarov
parent f8d8e5803c
commit 27de62e778
2 changed files with 12 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
kernel/locking/rtmutex.c
View File

@ -1141,6 +1141,7 @@ void __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)
void __lockfunc rt_spin_lock(spinlock_t *lock)
{
sleeping_lock_inc();
rcu_read_lock();
migrate_disable();
spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
@ -1156,6 +1157,7 @@ void __lockfunc __rt_spin_lock(struct rt_mutex *lock)
void __lockfunc rt_spin_lock_nested(spinlock_t *lock, int subclass)
{
sleeping_lock_inc();
rcu_read_lock();
migrate_disable();
spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
@ -1169,6 +1171,7 @@ void __lockfunc rt_spin_unlock(spinlock_t *lock)
spin_release(&lock->dep_map, 1, _RET_IP_);
rt_spin_lock_fastunlock(&lock->lock, rt_spin_lock_slowunlock);
migrate_enable();
rcu_read_unlock();
sleeping_lock_dec();
}
EXPORT_SYMBOL(rt_spin_unlock);
@ -1200,6 +1203,7 @@ int __lockfunc rt_spin_trylock(spinlock_t *lock)
ret = __rt_mutex_trylock(&lock->lock);
if (ret) {
spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
rcu_read_lock();
} else {
migrate_enable();
sleeping_lock_dec();
@ -1216,6 +1220,7 @@ int __lockfunc rt_spin_trylock_bh(spinlock_t *lock)
ret = __rt_mutex_trylock(&lock->lock);
if (ret) {
sleeping_lock_inc();
rcu_read_lock();
migrate_disable();
spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
} else
@ -1232,6 +1237,7 @@ int __lockfunc rt_spin_trylock_irqsave(spinlock_t *lock, unsigned long *flags)
ret = __rt_mutex_trylock(&lock->lock);
if (ret) {
sleeping_lock_inc();
rcu_read_lock();
migrate_disable();
spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
}

6
kernel/locking/rwlock-rt.c
View File

@ -310,6 +310,7 @@ int __lockfunc rt_read_trylock(rwlock_t *rwlock)
ret = do_read_rt_trylock(rwlock);
if (ret) {
rwlock_acquire_read(&rwlock->dep_map, 0, 1, _RET_IP_);
rcu_read_lock();
} else {
migrate_enable();
sleeping_lock_dec();
@ -327,6 +328,7 @@ int __lockfunc rt_write_trylock(rwlock_t *rwlock)
ret = do_write_rt_trylock(rwlock);
if (ret) {
rwlock_acquire(&rwlock->dep_map, 0, 1, _RET_IP_);
rcu_read_lock();
} else {
migrate_enable();
sleeping_lock_dec();
@ -338,6 +340,7 @@ EXPORT_SYMBOL(rt_write_trylock);
void __lockfunc rt_read_lock(rwlock_t *rwlock)
{
sleeping_lock_inc();
rcu_read_lock();
migrate_disable();
rwlock_acquire_read(&rwlock->dep_map, 0, 0, _RET_IP_);
do_read_rt_lock(rwlock);
@ -347,6 +350,7 @@ EXPORT_SYMBOL(rt_read_lock);
void __lockfunc rt_write_lock(rwlock_t *rwlock)
{
sleeping_lock_inc();
rcu_read_lock();
migrate_disable();
rwlock_acquire(&rwlock->dep_map, 0, 0, _RET_IP_);
do_write_rt_lock(rwlock);
@ -358,6 +362,7 @@ void __lockfunc rt_read_unlock(rwlock_t *rwlock)
rwlock_release(&rwlock->dep_map, 1, _RET_IP_);
do_read_rt_unlock(rwlock);
migrate_enable();
rcu_read_unlock();
sleeping_lock_dec();
}
EXPORT_SYMBOL(rt_read_unlock);
@ -367,6 +372,7 @@ void __lockfunc rt_write_unlock(rwlock_t *rwlock)
rwlock_release(&rwlock->dep_map, 1, _RET_IP_);
do_write_rt_unlock(rwlock);
migrate_enable();
rcu_read_unlock();
sleeping_lock_dec();
}
EXPORT_SYMBOL(rt_write_unlock);