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ipc,msg: document volatile r_msg

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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>
This commit is contained in:
Davidlohr Bueso 2014-06-06 14:37:46 -07:00 • committed by Linus Torvalds
parent 3440a6bd1d
commit 4bb6657dd3
1 changed files with 7 additions and 3 deletions
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10
ipc/msg.c
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@ -42,9 +42,7 @@
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include "util.h" #include "util.h"
/* /* one msg_receiver structure for each sleeping receiver */
* one msg_receiver structure for each sleeping receiver:
*/
struct msg_receiver { struct msg_receiver {
struct list_head r_list; struct list_head r_list;
struct task_struct *r_tsk; struct task_struct *r_tsk;
@ -53,6 +51,12 @@ struct msg_receiver {
long r_msgtype; long r_msgtype;
long r_maxsize; 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; struct msg_msg *volatile r_msg;
}; };