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authorDavidlohr Bueso <davidlohr@hp.com>2014-06-06 14:37:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-06 16:08:15 -0700
commit4bb6657dd3a55ab507502d82dbee9db276602669 (patch)
tree1f1f5f3edd91b4d7cd4244d2485fdadd794c0265 /ipc
parent3440a6bd1d2eeb27276f6bd410e0902dcba09f0e (diff)
downloadlinux-stericsson-4bb6657dd3a55ab507502d82dbee9db276602669.tar.gz
ipc,msg: document volatile r_msg
The need for volatile is not obvious, document it. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/msg.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/ipc/msg.c b/ipc/msg.c
index 6d33e30c7c39..c5d8e3749985 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -42,9 +42,7 @@
#include <linux/uaccess.h>
#include "util.h"
-/*
- * one msg_receiver structure for each sleeping receiver:
- */
+/* one msg_receiver structure for each sleeping receiver */
struct msg_receiver {
struct list_head r_list;
struct task_struct *r_tsk;
@@ -53,6 +51,12 @@ struct msg_receiver {
long r_msgtype;
long r_maxsize;
+ /*
+ * Mark r_msg volatile so that the compiler
+ * does not try to get smart and optimize
+ * it. We rely on this for the lockless
+ * receive algorithm.
+ */
struct msg_msg *volatile r_msg;
};