Commit 81e7761b authored by David Howells's avatar David Howells Committed by Jakub Kicinski
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rxrpc: Only set DF=1 on initial DATA transmission 



Change how the DF flag is managed on DATA transmissions.  Set it on initial
transmission and don't set it on retransmissions.  Then remove the handling
for EMSGSIZE in rxrpc_send_data_packet() and just pretend it didn't happen,
leaving it to the retransmission path to retry.

The path-MTU discovery using PING ACKs is then used to probe for the
maximum DATA size - though notification by ICMP will be used if one is
received.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20241204074710.990092-16-dhowells@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent cd69a07b

net/rxrpc/ar-internal.h

+1 −0
Original line number Diff line number Diff line
@@ -98,6 +98,7 @@ struct rxrpc_net { 
	atomic_t		stat_tx_data_send;

	atomic_t		stat_tx_data_send_frag;

	atomic_t		stat_tx_data_send_fail;

	atomic_t		stat_tx_data_send_msgsize;

	atomic_t		stat_tx_data_underflow;

	atomic_t		stat_tx_data_cwnd_reset;

	atomic_t		stat_rx_data;

net/rxrpc/output.c

+16 −16
Original line number Diff line number Diff line
@@ -552,16 +552,11 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t 
	msg.msg_controllen = 0;

	msg.msg_flags	= MSG_SPLICE_PAGES;



	/* Track what we've attempted to transmit at least once so that the

	 * retransmission algorithm doesn't try to resend what we haven't sent

	 * yet.

	/* Send the packet with the don't fragment bit set unless we think it's

	 * too big or if this is a retransmission.

	 */

	if (txb->seq == call->tx_transmitted + 1)

		call->tx_transmitted = txb->seq + n - 1;



	/* send the packet with the don't fragment bit set if we currently

	 * think it's small enough */

	if (len >= sizeof(struct rxrpc_wire_header) + call->peer->max_data) {

	if (txb->seq == call->tx_transmitted + 1 &&

	    len >= sizeof(struct rxrpc_wire_header) + call->peer->max_data) {

		rxrpc_local_dont_fragment(conn->local, false);

		frag = rxrpc_tx_point_call_data_frag;

	} else {
@@ -569,6 +564,13 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t 
		frag = rxrpc_tx_point_call_data_nofrag;

	}



	/* Track what we've attempted to transmit at least once so that the

	 * retransmission algorithm doesn't try to resend what we haven't sent

	 * yet.

	 */

	if (txb->seq == call->tx_transmitted + 1)

		call->tx_transmitted = txb->seq + n - 1;



	if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {

		static int lose;
@@ -580,7 +582,6 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t 
		}

	}



retry:

	/* send the packet by UDP

	 * - returns -EMSGSIZE if UDP would have to fragment the packet

	 *   to go out of the interface
@@ -591,7 +592,11 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t 
	ret = do_udp_sendmsg(conn->local->socket, &msg, len);

	conn->peer->last_tx_at = ktime_get_seconds();



	if (ret < 0) {

	if (ret == -EMSGSIZE) {

		rxrpc_inc_stat(call->rxnet, stat_tx_data_send_msgsize);

		trace_rxrpc_tx_packet(call->debug_id, call->local->kvec[0].iov_base, frag);

		ret = 0;

	} else if (ret < 0) {

		rxrpc_inc_stat(call->rxnet, stat_tx_data_send_fail);

		trace_rxrpc_tx_fail(call->debug_id, txb->serial, ret, frag);

	} else {
@@ -599,11 +604,6 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t 
	}



	rxrpc_tx_backoff(call, ret);

	if (ret == -EMSGSIZE && frag == rxrpc_tx_point_call_data_nofrag) {

		rxrpc_local_dont_fragment(conn->local, false);

		frag = rxrpc_tx_point_call_data_frag;

		goto retry;

	}



done:

	if (ret >= 0) {

net/rxrpc/proc.c

+3 −2
Original line number Diff line number Diff line
@@ -473,10 +473,11 @@ int rxrpc_stats_show(struct seq_file *seq, void *v) 
	struct rxrpc_net *rxnet = rxrpc_net(seq_file_single_net(seq));



	seq_printf(seq,

		   "Data     : send=%u sendf=%u fail=%u\n",

		   "Data     : send=%u sendf=%u fail=%u emsz=%u\n",

		   atomic_read(&rxnet->stat_tx_data_send),

		   atomic_read(&rxnet->stat_tx_data_send_frag),

		   atomic_read(&rxnet->stat_tx_data_send_fail));

		   atomic_read(&rxnet->stat_tx_data_send_fail),

		   atomic_read(&rxnet->stat_tx_data_send_msgsize));

	seq_printf(seq,

		   "Data-Tx  : nr=%u retrans=%u uf=%u cwr=%u\n",

		   atomic_read(&rxnet->stat_tx_data),