rxrpc: Improve jumbo packet counting

Improve the information stored about jumbo packets so that we don't need to
reparse them so much later.

Signed-off-by: David Howells <[e-mail]>
Reviewed-by: Jeffrey Altman <[e-mail]>

net/rxrpc/ar-internal.h

···
  * - max 48 bytes (struct sk_buff::cb)
  */
 struct rxrpc_skb_priv {
-	union {
-		u8		nr_jumbo;	/* Number of jumbo subpackets */
-	};
+	u8		nr_subpackets;		/* Number of subpackets */
+	u8		rx_flags;		/* Received packet flags */
+#define RXRPC_SKB_INCL_LAST	0x01		/* - Includes last packet */
 	union {
 		int		remain;		/* amount of space remaining for next write */
+
+		/* List of requested ACKs on subpackets */
+		unsigned long	rx_req_ack[(RXRPC_MAX_NR_JUMBO + BITS_PER_LONG - 1) /
+					   BITS_PER_LONG];
 	};
 
 	struct rxrpc_host_header hdr;		/* RxRPC packet header from this packet */

net/rxrpc/input.c

···
 }
 
 /*
- * Scan a jumbo packet to validate its structure and to work out how many
+ * Scan a data packet to validate its structure and to work out how many
  * subpackets it contains.
  *
  * A jumbo packet is a collection of consecutive packets glued together with
···
  * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
  * size.
  */
-static bool rxrpc_validate_jumbo(struct sk_buff *skb)
+static bool rxrpc_validate_data(struct sk_buff *skb)
 {
 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 	unsigned int offset = sizeof(struct rxrpc_wire_header);
 	unsigned int len = skb->len;
-	int nr_jumbo = 1;
 	u8 flags = sp->hdr.flags;
 
-	do {
-		nr_jumbo++;
+	for (;;) {
+		if (flags & RXRPC_REQUEST_ACK)
+			__set_bit(sp->nr_subpackets, sp->rx_req_ack);
+		sp->nr_subpackets++;
+
+		if (!(flags & RXRPC_JUMBO_PACKET))
+			break;
+
 		if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
 			goto protocol_error;
 		if (flags & RXRPC_LAST_PACKET)
···
 		if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 			goto protocol_error;
 		offset += sizeof(struct rxrpc_jumbo_header);
-	} while (flags & RXRPC_JUMBO_PACKET);
+	}
 
-	sp->nr_jumbo = nr_jumbo;
+	if (flags & RXRPC_LAST_PACKET)
+		sp->rx_flags |= RXRPC_SKB_INCL_LAST;
 	return true;
 
 protocol_error:
···
 		if (sp->hdr.callNumber == 0 ||
 		    sp->hdr.seq == 0)
 			goto bad_message;
-		if (sp->hdr.flags & RXRPC_JUMBO_PACKET &&
-		    !rxrpc_validate_jumbo(skb))
+		if (!rxrpc_validate_data(skb))
 			goto bad_message;
 		break;
 

net/rxrpc/protocol.h

···
 #define RXRPC_JUMBO_DATALEN	1412	/* non-terminal jumbo packet data length */
 #define RXRPC_JUMBO_SUBPKTLEN	(RXRPC_JUMBO_DATALEN + sizeof(struct rxrpc_jumbo_header))
 
+/*
+ * The maximum number of subpackets that can possibly fit in a UDP packet is:
+ *
+ *	((max_IP - IP_hdr - UDP_hdr) / RXRPC_JUMBO_SUBPKTLEN) + 1
+ *	= ((65535 - 28 - 28) / 1416) + 1
+ *	= 46 non-terminal packets and 1 terminal packet.
+ */
+#define RXRPC_MAX_NR_JUMBO	47
+
 /*****************************************************************************/
 /*
  * on-the-wire Rx ACK packet data payload