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authorPaul E. McKenney <paul.mckenney@linaro.org>2011-08-17 00:46:46 (GMT)
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-09-29 04:38:43 (GMT)
commit5342e269b2b58ee0b0b4168a94087faaa60d0567 (patch)
tree77467d64948328e506f06eaf5a719de7fade4b83 /kernel/rtmutex.c
parent06ae115a1d551cd952d80df06eaf8b5153351875 (diff)
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rcu: Permit rt_mutex_unlock() with irqs disabled
Create a separate lockdep class for the rt_mutex used for RCU priority boosting and enable use of rt_mutex_lock() with irqs disabled. This prevents RCU priority boosting from falling prey to deadlocks when someone begins an RCU read-side critical section in preemptible state, but releases it with an irq-disabled lock held. Unfortunately, the scheduler's runqueue and priority-inheritance locks still must either completely enclose or be completely enclosed by any overlapping RCU read-side critical section. This version removes a redundant local_irq_restore() noted by Yong Zhang. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rtmutex.c')
-rw-r--r--kernel/rtmutex.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index 255e166..5e8d9cc 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -579,6 +579,7 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
struct rt_mutex_waiter *waiter)
{
int ret = 0;
+ int was_disabled;
for (;;) {
/* Try to acquire the lock: */
@@ -601,10 +602,17 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
raw_spin_unlock(&lock->wait_lock);
+ was_disabled = irqs_disabled();
+ if (was_disabled)
+ local_irq_enable();
+
debug_rt_mutex_print_deadlock(waiter);
schedule_rt_mutex(lock);
+ if (was_disabled)
+ local_irq_disable();
+
raw_spin_lock(&lock->wait_lock);
set_current_state(state);
}