ipc: simplify message copying

Remove the redundant and confusing fill_copy().  Also add copy_msg()
check for error.  In this case exit from the function have to be done
instead of break, because further code interprets any error as EAGAIN.

Also define copy_msg() for the case when CONFIG_CHECKPOINT_RESTORE is
disabled.

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>

2 files changed, 14 insertions, 16 deletions

diff --git a/ipc/msg.c b/ipc/msg.c
index 038a7d79eb0e..8493e1d7e353 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -770,16 +770,6 @@ static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
 }
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
-static inline struct msg_msg *fill_copy(unsigned long copy_nr,
-                                        unsigned long msg_nr,
-                                        struct msg_msg *msg,
-                                        struct msg_msg *copy)
-{
-        if (copy_nr == msg_nr)
-                return copy_msg(msg, copy);
-        return NULL;
-}
-
 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz,
                                            int msgflg, long *msgtyp,
                                            unsigned long *copy_number)
@@ -803,8 +793,6 @@ static inline void free_copy(struct msg_msg *copy)
                 free_msg(copy);
 }
 #else
-#define fill_copy(copy_nr, msg_nr, msg, copy)           NULL
-
 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz,
                                            int msgflg, long *msgtyp,
                                            unsigned long *copy_number)
@@ -868,11 +856,16 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp,
                                                 walk_msg->m_type != 1) {
                                         msgtyp = walk_msg->m_type - 1;
                                 } else if (msgflg & MSG_COPY) {
-                                        msg = fill_copy(copy_number,
-                                                        msg_counter,
-                                                        walk_msg, copy);
-                                        if (msg)
+                                        if (copy_number == msg_counter) {
+                                                /*
+                                                 * Found requested message.
+                                                 * Copy it.
+                                                 */
+                                                msg = copy_msg(msg, copy);
+                                                if (IS_ERR(msg))
+                                                        goto out_unlock;
                                                 break;
+                                        }
                                 } else
                                         break;
                                 msg_counter++;
diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index 7eecdad40efc..ebfcbfa8b7f2 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -140,6 +140,11 @@ struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 
         return dst;
 }
+#else
+struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
+{
+        return ERR_PTR(-ENOSYS);
+}
 #endif
 int store_msg(void __user *dest, struct msg_msg *msg, int len)
 {