Merge branch 'linus' into irq/core to pick up dependencies.

2 files changed, 18 insertions, 8 deletions

diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 38ece035039e..d880296245c5 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -379,6 +379,14 @@ queue:
 	tail = encode_tail(smp_processor_id(), idx);
 
 	node += idx;
+
+	/*
+	 * Ensure that we increment the head node->count before initialising
+	 * the actual node. If the compiler is kind enough to reorder these
+	 * stores, then an IRQ could overwrite our assignments.
+	 */
+	barrier();
+
 	node->locked = 0;
 	node->next = NULL;
 	pv_init_node(node);
@@ -408,14 +416,15 @@ queue:
 	 */
 	if (old & _Q_TAIL_MASK) {
 		prev = decode_tail(old);
+
 		/*
-		 * The above xchg_tail() is also a load of @lock which
-		 * generates, through decode_tail(), a pointer.  The address
-		 * dependency matches the RELEASE of xchg_tail() such that
-		 * the subsequent access to @prev happens after.
+		 * We must ensure that the stores to @node are observed before
+		 * the write to prev->next. The address dependency from
+		 * xchg_tail is not sufficient to ensure this because the read
+		 * component of xchg_tail is unordered with respect to the
+		 * initialisation of @node.
 		 */
-
-		WRITE_ONCE(prev->next, node);
+		smp_store_release(&prev->next, node);
 
 		pv_wait_node(node, prev);
 		arch_mcs_spin_lock_contended(&node->locked);
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 65cc0cb984e6..940633c63254 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1616,11 +1616,12 @@ bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock,
 void __sched rt_mutex_futex_unlock(struct rt_mutex *lock)
 {
 	DEFINE_WAKE_Q(wake_q);
+	unsigned long flags;
 	bool postunlock;
 
-	raw_spin_lock_irq(&lock->wait_lock);
+	raw_spin_lock_irqsave(&lock->wait_lock, flags);
 	postunlock = __rt_mutex_futex_unlock(lock, &wake_q);
-	raw_spin_unlock_irq(&lock->wait_lock);
+	raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
 
 	if (postunlock)
 		rt_mutex_postunlock(&wake_q);