Subject: + ipcmsg-document-volatile-r_msg.patch added to -mm tree
To: davidlohr@xxxxxx,aswin@xxxxxx,manfred@xxxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 13 May 2014 13:39:29 -0700
The patch titled
Subject: ipc,msg: document volatile r_msg
has been added to the -mm tree. Its filename is
ipcmsg-document-volatile-r_msg.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipcmsg-document-volatile-r_msg.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipcmsg-document-volatile-r_msg.patch
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From: Davidlohr Bueso <davidlohr@xxxxxx>
Subject: ipc,msg: document volatile r_msg
The need for volatile is not obvious, document it.
Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Aswin Chandramouleeswaran <aswin@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/msg.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff -puN ipc/msg.c~ipcmsg-document-volatile-r_msg ipc/msg.c
--- a/ipc/msg.c~ipcmsg-document-volatile-r_msg
+++ a/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;
@@ -54,6 +52,12 @@ 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;
};
_
Patches currently in -mm which might be from davidlohr@xxxxxx are
mmvmacache-add-debug-data.patch
mmvmacache-optimize-overflow-system-wide-flushing.patch
mm-pass-vm_bug_on-reason-to-dump_page.patch
mm-pass-vm_bug_on-reason-to-dump_page-fix.patch
hugetlb-prep_compound_gigantic_page-drop-__init-marker.patch
hugetlb-add-hstate_is_gigantic.patch
hugetlb-update_and_free_page-dont-clear-pg_reserved-bit.patch
hugetlb-move-helpers-up-in-the-file.patch
hugetlb-add-support-for-gigantic-page-allocation-at-runtime.patch
m68k-call-find_vma-with-the-mmap_sem-held-in-sys_cacheflush.patch
mips-call-find_vma-with-the-mmap_sem-held.patch
arc-call-find_vma-with-the-mmap_sem-held.patch
arc-call-find_vma-with-the-mmap_sem-held-fix.patch
drm-exynos-call-find_vma-with-the-mmap_sem-held.patch
ipc-constify-ipc_ops.patch
ipc-shmc-check-for-ulong-overflows-in-shmat.patch
ipc-shmc-check-for-overflows-of-shm_tot.patch
ipc-shmc-check-for-integer-overflow-during-shmget.patch
ipc-shmc-increase-the-defaults-for-shmall-shmmax.patch
ipcshm-document-new-limits-in-the-uapi-header.patch
ipcshm-document-new-limits-in-the-uapi-header-v2.patch
ipcmsg-use-current-state-helpers.patch
ipcmsg-move-some-msgq-ns-code-around.patch
ipcmsg-always-respect-msg_noerror.patch
ipcmsg-document-volatile-r_msg.patch
ipcmsg-loosen-check-for-full-queue.patch
linux-next.patch
blackfin-ptrace-call-find_vma-with-the-mmap_sem-held.patch
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