[LLC]: fix llc_ui_recvmsg, making it behave like tcp_recvmsg

In fact it is an exact copy of the parts that makes sense to LLC :-)
Signed-off-by: NArnaldo Carvalho de Melo <acme@mandriva.com>

include/net/llc_conn.h

@@ -38,6 +38,7 @@ struct llc_sock {
 	struct llc_addr	    laddr;		/* lsap/mac pair */
 	struct llc_addr	    daddr;		/* dsap/mac pair */
 	struct net_device   *dev;		/* device to send to remote */
+	u32		    copied_seq;		/* head of yet unread data */
 	u8		    retry_count;	/* number of retries */
 	u8		    ack_must_be_send;
 	u8		    first_pdu_Ns;

net/llc/af_llc.c

@@ -648,53 +648,167 @@ static int llc_ui_accept(struct socket *sock, struct socket *newsock, int flags)
  *	llc_ui_recvmsg - copy received data to the socket user.
  *	@sock: Socket to copy data from.
  *	@msg: Various user space related information.
- *	@size: Size of user buffer.
+ *	@len: Size of user buffer.
  *	@flags: User specified flags.
  *
  *	Copy received data to the socket user.
  *	Returns non-negative upon success, negative otherwise.
  */
 static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock,
-			  struct msghdr *msg, size_t size, int flags)
+			  struct msghdr *msg, size_t len, int flags)
 {
-	struct sock *sk = sock->sk;
 	struct sockaddr_llc *uaddr = (struct sockaddr_llc *)msg->msg_name;
-	struct sk_buff *skb;
+	const int nonblock = flags & MSG_DONTWAIT;
+	struct sk_buff *skb = NULL;
+	struct sock *sk = sock->sk;
+	struct llc_sock *llc = llc_sk(sk);
 	size_t copied = 0;
-	int rc = -ENOMEM;
-	int noblock = flags & MSG_DONTWAIT;
+	u32 peek_seq = 0;
+	u32 *seq;
+	unsigned long used;
+	int target;	/* Read at least this many bytes */
+	long timeo;
 
-	dprintk("%s: receiving in %02X from %02X\n", __FUNCTION__,
-		llc_sk(sk)->laddr.lsap, llc_sk(sk)->daddr.lsap);
 	lock_sock(sk);
-	if (skb_queue_empty(&sk->sk_receive_queue)) {
-		rc = llc_wait_data(sk, sock_rcvtimeo(sk, noblock));
-		if (rc)
+	copied = -ENOTCONN;
+	if (sk->sk_state == TCP_LISTEN)
 		goto out;
+
+	timeo = sock_rcvtimeo(sk, nonblock);
+
+	seq = &llc->copied_seq;
+	if (flags & MSG_PEEK) {
+		peek_seq = llc->copied_seq;
+		seq = &peek_seq;
  	}
-	skb = skb_dequeue(&sk->sk_receive_queue);
-	if (!skb) /* shutdown */
-		goto out;
-	copied = skb->len;
-	if (copied > size)
-		copied = size;
-	rc = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
-	if (rc)
-		goto dgram_free;
-	if (skb->len > copied) {
-		skb_pull(skb, copied);
-		skb_queue_head(&sk->sk_receive_queue, skb);
+
+	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
+	copied = 0;
+
+	do {
+		u32 offset;
+
+		/*
+		 * We need to check signals first, to get correct SIGURG
+		 * handling. FIXME: Need to check this doesn't impact 1003.1g
+		 * and move it down to the bottom of the loop
+		 */
+		if (signal_pending(current)) {
+			if (copied)
+				break;
+			copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
+			break;
 		}
-	if (uaddr)
-		memcpy(uaddr, llc_ui_skb_cb(skb), sizeof(*uaddr));
-	msg->msg_namelen = sizeof(*uaddr);
-	if (!skb->next) {
-dgram_free:
-		kfree_skb(skb);
+
+		/* Next get a buffer. */
+
+		skb = skb_peek(&sk->sk_receive_queue);
+		if (skb) {
+			offset = *seq;
+			goto found_ok_skb;
 		}
+		/* Well, if we have backlog, try to process it now yet. */
+
+		if (copied >= target && !sk->sk_backlog.tail)
+			break;
+
+		if (copied) {
+			if (sk->sk_err ||
+			    sk->sk_state == TCP_CLOSE ||
+			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
+			    !timeo ||
+			    (flags & MSG_PEEK))
+				break;
+		} else {
+			if (sock_flag(sk, SOCK_DONE))
+				break;
+
+			if (sk->sk_err) {
+				copied = sock_error(sk);
+				break;
+			}
+			if (sk->sk_shutdown & RCV_SHUTDOWN)
+				break;
+
+			if (sk->sk_state == TCP_CLOSE) {
+				if (!sock_flag(sk, SOCK_DONE)) {
+					/*
+					 * This occurs when user tries to read
+					 * from never connected socket.
+					 */
+					copied = -ENOTCONN;
+					break;
+				}
+				break;
+			}
+			if (!timeo) {
+				copied = -EAGAIN;
+				break;
+			}
+		}
+
+		if (copied >= target) { /* Do not sleep, just process backlog. */
+			release_sock(sk);
+			lock_sock(sk);
+		} else
+			sk_wait_data(sk, &timeo);
+
+		if ((flags & MSG_PEEK) && peek_seq != llc->copied_seq) {
+			if (net_ratelimit())
+				printk(KERN_DEBUG "LLC(%s:%d): Application "
+						  "bug, race in MSG_PEEK.\n",
+				       current->comm, current->pid);
+			peek_seq = llc->copied_seq;
+		}
+		continue;
+	found_ok_skb:
+		/* Ok so how much can we use? */
+		used = skb->len - offset;
+		if (len < used)
+			used = len;
+
+		if (!(flags & MSG_TRUNC)) {
+			int rc = skb_copy_datagram_iovec(skb, offset,
+							 msg->msg_iov, used);
+			if (rc) {
+				/* Exception. Bailout! */
+				if (!copied)
+					copied = -EFAULT;
+				break;
+			}
+		}
+
+		*seq += used;
+		copied += used;
+		len -= used;
+
+		if (used + offset < skb->len)
+			continue;
+
+		if (!(flags & MSG_PEEK)) {
+			sk_eat_skb(sk, skb);
+			*seq = 0;
+		}
+	} while (len > 0);
+
+	/* 
+	 * According to UNIX98, msg_name/msg_namelen are ignored
+	 * on connected socket. -ANK
+	 * But... af_llc still doesn't have separate sets of methods for
+	 * SOCK_DGRAM and SOCK_STREAM :-( So we have to do this test, will
+	 * eventually fix this tho :-) -acme
+	 */
+	if (sk->sk_type == SOCK_DGRAM)
+		goto copy_uaddr;
 out:
 	release_sock(sk);
-	return rc ? : copied;
+	return copied;
+copy_uaddr:
+	if (uaddr != NULL && skb != NULL) {
+		memcpy(uaddr, llc_ui_skb_cb(skb), sizeof(*uaddr));
+		msg->msg_namelen = sizeof(*uaddr);
+	}
+	goto out;
 }
 
 /**

net/llc/llc_conn.c

@@ -120,8 +120,8 @@ int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
 			sk->sk_socket->state  = SS_UNCONNECTED;
 			sk->sk_state          = TCP_CLOSE;
 			if (!sock_flag(sk, SOCK_DEAD)) {
-				sk->sk_state_change(sk);
 				sock_set_flag(sk, SOCK_DEAD);
+				sk->sk_state_change(sk);
 			}
 		}
 		kfree_skb(skb);

net/llc/llc_proc.c

@@ -134,7 +134,7 @@ static int llc_seq_socket_show(struct seq_file *seq, void *v)
 	llc_ui_format_mac(seq, llc->daddr.mac);
 	seq_printf(seq, "@%02X %8d %8d %2d %3d %4d\n", llc->daddr.lsap,
 		   atomic_read(&sk->sk_wmem_alloc),
-		   atomic_read(&sk->sk_rmem_alloc),
+		   atomic_read(&sk->sk_rmem_alloc) - llc->copied_seq,
 		   sk->sk_state,
 		   sk->sk_socket ? SOCK_INODE(sk->sk_socket)->i_uid : -1,
 		   llc->link);

net/llc/llc_sap.c

@@ -49,9 +49,12 @@ struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev)
 
 void llc_save_primitive(struct sock *sk, struct sk_buff* skb, u8 prim)
 {
-	struct sockaddr_llc *addr = llc_ui_skb_cb(skb);
+	struct sockaddr_llc *addr;
 
+	if (skb->sk->sk_type == SOCK_STREAM) /* See UNIX98 */
+		return;
        /* save primitive for use by the user. */
+	addr		  = llc_ui_skb_cb(skb);
 	addr->sllc_family = sk->sk_family;
 	addr->sllc_arphrd = skb->dev->type;
 	addr->sllc_test   = prim == LLC_TEST_PRIM;