X-Git-Url: http://git.cascardo.info/?a=blobdiff_plain;f=kernel%2Flocking%2Fmutex.h;h=6cd6b8e9efd7f73175be41f46d062650da821af8;hb=8e4ef6386703835f91898334b72e48649646ec00;hp=a68bae5e852a08f1c0d75587b57c5e31835f937e;hpb=9454c23852ca6d7aec89fd6fd46a046c323caac3;p=cascardo%2Flinux.git

diff --git a/kernel/locking/mutex.h b/kernel/locking/mutex.h
index a68bae5e852a..6cd6b8e9efd7 100644
--- a/kernel/locking/mutex.h
+++ b/kernel/locking/mutex.h
@@ -17,14 +17,20 @@
 		__list_del((waiter)->list.prev, (waiter)->list.next)
 
 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+/*
+ * The mutex owner can get read and written to locklessly.
+ * We should use WRITE_ONCE when writing the owner value to
+ * avoid store tearing, otherwise, a thread could potentially
+ * read a partially written and incomplete owner value.
+ */
 static inline void mutex_set_owner(struct mutex *lock)
 {
-	lock->owner = current;
+	WRITE_ONCE(lock->owner, current);
 }
 
 static inline void mutex_clear_owner(struct mutex *lock)
 {
-	lock->owner = NULL;
+	WRITE_ONCE(lock->owner, NULL);
 }
 #else
 static inline void mutex_set_owner(struct mutex *lock)