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rxrpc: Only set DF=1 on initial DATA transmission

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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: David 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: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
David Howells
2024-12-04 07:46:43 +00:00
committed by Jakub Kicinski
parent cd69a07b6d
commit 81e7761be5
3 changed files with 20 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
net/rxrpc/ar-internal.h
View File

@@ -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;

32
net/rxrpc/output.c
View File

@@ -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) {

5
net/rxrpc/proc.c
View File

@@ -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),