From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Mon, 12 Oct 2015 23:56:42 +0000 (-0700)
Subject: list: Use WRITE_ONCE() when initializing list_head structures
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2f073848c3cc8aff2655ab7c46d8c0de90cf4e50;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

list: Use WRITE_ONCE() when initializing list_head structures

Code that does lockless emptiness testing of non-RCU lists is relying
on INIT_LIST_HEAD() to write the list head's ->next pointer atomically,
particularly when INIT_LIST_HEAD() is invoked from list_del_init().
This commit therefore adds WRITE_ONCE() to this function's pointer stores
that could affect the head's ->next pointer.

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---

diff --git a/include/linux/list.h b/include/linux/list.h
index 06c2d887a918..5356f4d661a7 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -24,7 +24,7 @@
 
 static inline void INIT_LIST_HEAD(struct list_head *list)
 {
-	list->next = list;
+	WRITE_ONCE(list->next, list);
 	list->prev = list;
 }