rxrpc: Keep the skb private record of the Rx header in host byte order

Currently, a copy of the Rx packet header is copied into the the sk_buff
private data so that we can advance the pointer into the buffer,
potentially discarding the original.  At the moment, this copy is held in
network byte order, but this means we're doing a lot of unnecessary
translations.

The reasons it was done this way are that we need the values in network
byte order occasionally and we can use the copy, slightly modified, as part
of an iov array when sending an ack or an abort packet.

However, it seems more reasonable on review that it would be better kept in
host byte order and that we make up a new header when we want to send
another packet.

To this end, rename the original header struct to rxrpc_wire_header (with
BE fields) and institute a variant called rxrpc_host_header that has host
order fields.  Change the struct in the sk_buff private data into an
rxrpc_host_header and translate the values when filling it in.

This further allows us to keep values kept in various structures in host
byte order rather than network byte order and allows removal of some fields
that are byteswapped duplicates.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 24 insertions, 16 deletions

diff --git a/net/rxrpc/ar-accept.c b/net/rxrpc/ar-accept.c
index 9a49f32e9e1e..73c905416271 100644
--- a/net/rxrpc/ar-accept.c
+++ b/net/rxrpc/ar-accept.c
@@ -27,7 +27,7 @@
  * generate a connection-level abort
  */
 static int rxrpc_busy(struct rxrpc_local *local, struct sockaddr_rxrpc *srx,
-		      struct rxrpc_header *hdr)
+		      struct rxrpc_wire_header *whdr)
 {
 	struct msghdr msg;
 	struct kvec iov[1];
@@ -36,25 +36,21 @@ static int rxrpc_busy(struct rxrpc_local *local, struct sockaddr_rxrpc *srx,
 
 	_enter("%d,,", local->debug_id);
 
+	whdr->type	= RXRPC_PACKET_TYPE_BUSY;
+	whdr->serial	= htonl(1);
+
 	msg.msg_name	= &srx->transport.sin;
 	msg.msg_namelen	= sizeof(srx->transport.sin);
 	msg.msg_control	= NULL;
 	msg.msg_controllen = 0;
 	msg.msg_flags	= 0;
 
-	hdr->seq	= 0;
-	hdr->type	= RXRPC_PACKET_TYPE_BUSY;
-	hdr->flags	= 0;
-	hdr->userStatus	= 0;
-	hdr->_rsvd	= 0;
-
-	iov[0].iov_base	= hdr;
-	iov[0].iov_len	= sizeof(*hdr);
+	iov[0].iov_base	= whdr;
+	iov[0].iov_len	= sizeof(*whdr);
 
 	len = iov[0].iov_len;
 
-	hdr->serial = htonl(1);
-	_proto("Tx BUSY %%%u", ntohl(hdr->serial));
+	_proto("Tx BUSY %%1");
 
 	ret = kernel_sendmsg(local->socket, &msg, iov, 1, len);
 	if (ret < 0) {
@@ -211,8 +207,8 @@ void rxrpc_accept_incoming_calls(struct work_struct *work)
 	struct rxrpc_skb_priv *sp;
 	struct sockaddr_rxrpc srx;
 	struct rxrpc_sock *rx;
+	struct rxrpc_wire_header whdr;
 	struct sk_buff *skb;
-	__be16 service_id;
 	int ret;
 
 	_enter("%d", local->debug_id);
@@ -240,6 +236,19 @@ process_next_packet:
 
 	sp = rxrpc_skb(skb);
 
+	/* Set up a response packet header in case we need it */
+	whdr.epoch	= htonl(sp->hdr.epoch);
+	whdr.cid	= htonl(sp->hdr.cid);
+	whdr.callNumber	= htonl(sp->hdr.callNumber);
+	whdr.seq	= htonl(sp->hdr.seq);
+	whdr.serial	= 0;
+	whdr.flags	= 0;
+	whdr.type	= 0;
+	whdr.userStatus	= 0;
+	whdr.securityIndex = sp->hdr.securityIndex;
+	whdr._rsvd	= 0;
+	whdr.serviceId	= htons(sp->hdr.serviceId);
+
 	/* determine the remote address */
 	memset(&srx, 0, sizeof(srx));
 	srx.srx_family = AF_RXRPC;
@@ -256,10 +265,9 @@ process_next_packet:
 	}
 
 	/* get the socket providing the service */
-	service_id = sp->hdr.serviceId;
 	read_lock_bh(&local->services_lock);
 	list_for_each_entry(rx, &local->services, listen_link) {
-		if (rx->service_id == service_id &&
+		if (rx->srx.srx_service == sp->hdr.serviceId &&
 		    rx->sk.sk_state != RXRPC_CLOSE)
 			goto found_service;
 	}
@@ -267,7 +275,7 @@ process_next_packet:
 	goto invalid_service;
 
 found_service:
-	_debug("found service %hd", ntohs(rx->service_id));
+	_debug("found service %hd", rx->srx.srx_service);
 	if (sk_acceptq_is_full(&rx->sk))
 		goto backlog_full;
 	sk_acceptq_added(&rx->sk);
@@ -296,7 +304,7 @@ found_service:
 backlog_full:
 	read_unlock_bh(&local->services_lock);
 busy:
-	rxrpc_busy(local, &srx, &sp->hdr);
+	rxrpc_busy(local, &srx, &whdr);
 	rxrpc_free_skb(skb);
 	goto process_next_packet;