ipc: message queue receive cleanup

Move all message related manipulation into one function msg_fill().
Actually, two functions because of the compat one.

[akpm@linux-foundation.org: checkpatch fixes]
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>

3 files changed, 45 insertions, 49 deletions

diff --git a/include/linux/msg.h b/include/linux/msg.h
index 7a4b9e97d29a..fc5743a554e6 100644
--- a/include/linux/msg.h
+++ b/include/linux/msg.h
@@ -34,7 +34,8 @@ struct msg_queue {
 /* Helper routines for sys_msgsnd and sys_msgrcv */
 extern long do_msgsnd(int msqid, long mtype, void __user *mtext,
                         size_t msgsz, int msgflg);
-extern long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
-                        size_t msgsz, long msgtyp, int msgflg);
+extern long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp,
+                      int msgflg,
+                      long (*msg_fill)(void __user *, struct msg_msg *, size_t));
 
 #endif /* _LINUX_MSG_H */
diff --git a/ipc/compat.c b/ipc/compat.c
index ad9518eb26e0..eb3ea16d2d1d 100644
--- a/ipc/compat.c
+++ b/ipc/compat.c
@@ -306,6 +306,20 @@ static long do_compat_semctl(int first, int second, int third, u32 pad)
         return err;
 }
 
+long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
+{
+        struct compat_msgbuf __user *msgp = dest;
+        size_t msgsz;
+
+        if (put_user(msg->m_type, &msgp->mtype))
+                return -EFAULT;
+
+        msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
+        if (store_msg(msgp->mtext, msg, msgsz))
+                return -EFAULT;
+        return msgsz;
+}
+
 #ifdef CONFIG_ARCH_WANT_OLD_COMPAT_IPC
 long compat_sys_semctl(int first, int second, int third, void __user *uptr)
 {
@@ -337,10 +351,6 @@ long compat_sys_msgsnd(int first, int second, int third, void __user *uptr)
 long compat_sys_msgrcv(int first, int second, int msgtyp, int third,
                            int version, void __user *uptr)
 {
-        struct compat_msgbuf __user *up;
-        long type;
-        int err;
-
         if (first < 0)
                 return -EINVAL;
         if (second < 0)
@@ -348,23 +358,14 @@ long compat_sys_msgrcv(int first, int second, int msgtyp, int third,
 
         if (!version) {
                 struct compat_ipc_kludge ipck;
-                err = -EINVAL;
                 if (!uptr)
-                        goto out;
-                err = -EFAULT;
+                        return -EINVAL;
                 if (copy_from_user (&ipck, uptr, sizeof(ipck)))
-                        goto out;
+                        return -EFAULT;
                 uptr = compat_ptr(ipck.msgp);
                 msgtyp = ipck.msgtyp;
         }
-        up = uptr;
-        err = do_msgrcv(first, &type, up->mtext, second, msgtyp, third);
-        if (err < 0)
-                goto out;
-        if (put_user(type, &up->mtype))
-                err = -EFAULT;
-out:
-        return err;
+        return do_msgrcv(first, uptr, second, msgtyp, third, compat_do_msg_fill);
 }
 #else
 long compat_sys_semctl(int semid, int semnum, int cmd, int arg)
@@ -385,16 +386,8 @@ long compat_sys_msgsnd(int msqid, struct compat_msgbuf __user *msgp,
 long compat_sys_msgrcv(int msqid, struct compat_msgbuf __user *msgp,
                        compat_ssize_t msgsz, long msgtyp, int msgflg)
 {
-        long err, mtype;
-
-        err =  do_msgrcv(msqid, &mtype, msgp->mtext, (ssize_t)msgsz, msgtyp, msgflg);
-        if (err < 0)
-                goto out;
-
-        if (put_user(mtype, &msgp->mtype))
-                err = -EFAULT;
- out:
-        return err;
+        return do_msgrcv(msqid, msgp, (ssize_t)msgsz, msgtyp, msgflg,
+                         compat_do_msg_fill);
 }
 #endif
 
diff --git a/ipc/msg.c b/ipc/msg.c
index 2f272fa76595..cefc24f46e3e 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -755,15 +755,30 @@ static inline int convert_mode(long *msgtyp, int msgflg)
         return SEARCH_EQUAL;
 }
 
-long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
-                size_t msgsz, long msgtyp, int msgflg)
+static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
+{
+        struct msgbuf __user *msgp = dest;
+        size_t msgsz;
+
+        if (put_user(msg->m_type, &msgp->mtype))
+                return -EFAULT;
+
+        msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
+        if (store_msg(msgp->mtext, msg, msgsz))
+                return -EFAULT;
+        return msgsz;
+}
+
+long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp,
+               int msgflg,
+               long (*msg_handler)(void __user *, struct msg_msg *, size_t))
 {
         struct msg_queue *msq;
         struct msg_msg *msg;
         int mode;
         struct ipc_namespace *ns;
 
-        if (msqid < 0 || (long) msgsz < 0)
+        if (msqid < 0 || (long) bufsz < 0)
                 return -EINVAL;
         mode = convert_mode(&msgtyp, msgflg);
         ns = current->nsproxy->ipc_ns;
@@ -804,7 +819,7 @@ long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
                          * Found a suitable message.
                          * Unlink it from the queue.
                          */
-                        if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
+                        if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
                                 msg = ERR_PTR(-E2BIG);
                                 goto out_unlock;
                         }
@@ -831,7 +846,7 @@ long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
                 if (msgflg & MSG_NOERROR)
                         msr_d.r_maxsize = INT_MAX;
                 else
-                        msr_d.r_maxsize = msgsz;
+                        msr_d.r_maxsize = bufsz;
                 msr_d.r_msg = ERR_PTR(-EAGAIN);
                 current->state = TASK_INTERRUPTIBLE;
                 msg_unlock(msq);
@@ -894,29 +909,16 @@ out_unlock:
         if (IS_ERR(msg))
                 return PTR_ERR(msg);
 
-        msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz;
-        *pmtype = msg->m_type;
-        if (store_msg(mtext, msg, msgsz))
-                msgsz = -EFAULT;
-
+        bufsz = msg_handler(buf, msg, bufsz);
         free_msg(msg);
 
-        return msgsz;
+        return bufsz;
 }
 
 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
                 long, msgtyp, int, msgflg)
 {
-        long err, mtype;
-
-        err =  do_msgrcv(msqid, &mtype, msgp->mtext, msgsz, msgtyp, msgflg);
-        if (err < 0)
-                goto out;
-
-        if (put_user(mtype, &msgp->mtype))
-                err = -EFAULT;
-out:
-        return err;
+        return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
 }
 
 #ifdef CONFIG_PROC_FS