3 files changed, 29 insertions, 5 deletions

diff --git a/include/linux/spinlock_rt.h b/include/linux/spinlock_rt.h
index 447c457..ac6f08b 100644
--- a/include/linux/spinlock_rt.h
+++ b/include/linux/spinlock_rt.h
@@ -22,6 +22,7 @@ extern void __lockfunc rt_spin_lock(spinlock_t *lock);
 extern unsigned long __lockfunc rt_spin_lock_trace_flags(spinlock_t *lock);
 extern void __lockfunc rt_spin_lock_nested(spinlock_t *lock, int subclass);
 extern void __lockfunc rt_spin_unlock(spinlock_t *lock);
+extern void __lockfunc rt_spin_unlock_after_trylock_in_irq(spinlock_t *lock);
 extern void __lockfunc rt_spin_unlock_wait(spinlock_t *lock);
 extern int __lockfunc rt_spin_trylock_irqsave(spinlock_t *lock, unsigned long *flags);
 extern int __lockfunc rt_spin_trylock_bh(spinlock_t *lock);
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index 82d1708..c70436b 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -955,10 +955,8 @@ static void  noinline __sched rt_spin_lock_slowlock(struct rt_mutex *lock)
 /*
  * Slow path to release a rt_mutex spin_lock style
  */
-static void  noinline __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)
+static void __sched __rt_spin_lock_slowunlock(struct rt_mutex *lock)
 {
-	raw_spin_lock(&lock->wait_lock);
-
 	debug_rt_mutex_unlock(lock);
 
 	rt_mutex_deadlock_account_unlock(current);
@@ -977,6 +975,23 @@ static void  noinline __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)
 	rt_mutex_adjust_prio(current);
 }
 
+static void  noinline __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)
+{
+	raw_spin_lock(&lock->wait_lock);
+	__rt_spin_lock_slowunlock(lock);
+}
+
+static void  noinline __sched rt_spin_lock_slowunlock_hirq(struct rt_mutex *lock)
+{
+	int ret;
+
+	do {
+		ret = raw_spin_trylock(&lock->wait_lock);
+	} while (!ret);
+
+	__rt_spin_lock_slowunlock(lock);
+}
+
 void __lockfunc rt_spin_lock(spinlock_t *lock)
 {
 	rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
@@ -1007,6 +1022,13 @@ void __lockfunc rt_spin_unlock(spinlock_t *lock)
 }
 EXPORT_SYMBOL(rt_spin_unlock);
 
+void __lockfunc rt_spin_unlock_after_trylock_in_irq(spinlock_t *lock)
+{
+	/* NOTE: we always pass in '1' for nested, for simplicity */
+	spin_release(&lock->dep_map, 1, _RET_IP_);
+	rt_spin_lock_fastunlock(&lock->lock, rt_spin_lock_slowunlock_hirq);
+}
+
 void __lockfunc __rt_spin_unlock(struct rt_mutex *lock)
 {
 	rt_spin_lock_fastunlock(lock, rt_spin_lock_slowunlock);
@@ -1353,7 +1375,8 @@ rt_mutex_slowtrylock(struct rt_mutex *lock)
 {
 	int ret = 0;
 
-	raw_spin_lock(&lock->wait_lock);
+	if (!raw_spin_trylock(&lock->wait_lock))
+		return ret;
 	init_lists(lock);
 
 	if (likely(rt_mutex_owner(lock) != current)) {
diff --git a/kernel/timer.c b/kernel/timer.c
index 03f4ddd..e30108e 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1400,7 +1400,7 @@ unsigned long get_next_timer_interrupt(unsigned long now)
 		expires = base->next_timer;
 	}
 #ifdef CONFIG_PREEMPT_RT_FULL
-	rt_spin_unlock(&base->lock);
+	rt_spin_unlock_after_trylock_in_irq(&base->lock);
 #else
 	spin_unlock(&base->lock);
 #endif