Merge "Merge android-4.4.135 (c9d74f2) into msm-4.4"

1 files changed, 8 insertions, 0 deletions

diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 8173bc7fec92..3b40c8809e52 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -423,6 +423,14 @@ 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);