ipc: add more comments to message copying related code
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/ipc/msg.c b/ipc/msg.c
index 8493e1d..950572f 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -770,6 +770,10 @@
}
#ifdef CONFIG_CHECKPOINT_RESTORE
+/*
+ * This function creates new kernel message structure, large enough to store
+ * bufsz message bytes.
+ */
static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz,
int msgflg, long *msgtyp,
unsigned long *copy_number)
@@ -881,6 +885,10 @@
msg = ERR_PTR(-E2BIG);
goto out_unlock;
}
+ /*
+ * If we are copying, then do not unlink message and do
+ * not update queue parameters.
+ */
if (msgflg & MSG_COPY)
goto out_unlock;
list_del(&msg->m_list);