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authorStanislav Kinsbursky <skinsbursky@parallels.com>2013-01-04 15:34:55 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-01-04 16:11:45 -0800
commit4a674f34ba04a002244edaf891b5da7fc1473ae8 (patch)
tree14544a5d49b4a218bac3f5995503c8e208735cef /ipc/util.h
parentf9dd87f4738c7555aca2cdf8cb2b2326cafb0cad (diff)
downloadvexpress-lsk-4a674f34ba04a002244edaf891b5da7fc1473ae8.tar.gz
ipc: introduce message queue copy feature
This patch is required for checkpoint/restore in userspace. c/r requires some way to get all pending IPC messages without deleting them from the queue (checkpoint can fail and in this case tasks will be resumed, so queue have to be valid). To achive this, new operation flag MSG_COPY for sys_msgrcv() system call was introduced. If this flag was specified, then mtype is interpreted as number of the message to copy. If MSG_COPY is set, then kernel will allocate dummy message with passed size, and then use new copy_msg() helper function to copy desired message (instead of unlinking it from the queue). Notes: 1) Return -ENOSYS if MSG_COPY is specified, but CONFIG_CHECKPOINT_RESTORE is not set. Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/util.h')
-rw-r--r--ipc/util.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/ipc/util.h b/ipc/util.h
index a61e0ca2bff..eeb79a1fbd8 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -140,6 +140,7 @@ int ipc_parse_version (int *cmd);
extern void free_msg(struct msg_msg *msg);
extern struct msg_msg *load_msg(const void __user *src, int len);
+extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
extern void recompute_msgmni(struct ipc_namespace *);