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| author | Davidlohr Bueso <davidlohr@hp.com> | 2014-06-06 14:37:46 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-06 16:08:15 -0700 |
| commit | 4bb6657dd3a55ab507502d82dbee9db276602669 (patch) | |
| tree | 1f1f5f3edd91b4d7cd4244d2485fdadd794c0265 /ipc | |
| parent | 3440a6bd1d2eeb27276f6bd410e0902dcba09f0e (diff) | |
| download | lwn-4bb6657dd3a55ab507502d82dbee9db276602669.tar.gz lwn-4bb6657dd3a55ab507502d82dbee9db276602669.zip | |
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.c | 10 |
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; }; |