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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next 14/37] rxrpc: Only set DF=1 on initial DATA transmission Date: Mon, 2 Dec 2024 14:30:32 +0000 Message-ID: <20241202143057.378147-15-dhowells@redhat.com> In-Reply-To: <20241202143057.378147-1-dhowells@redhat.com> References: <20241202143057.378147-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Patchwork-Delegate: kuba@kernel.org 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 cc: Marc Dionne cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: linux-afs@lists.infradead.org cc: netdev@vger.kernel.org --- net/rxrpc/ar-internal.h | 1 + net/rxrpc/output.c | 32 ++++++++++++++++---------------- net/rxrpc/proc.c | 5 +++-- 3 files changed, 20 insertions(+), 18 deletions(-) diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 55cc68dd1b40..84efa21f176c 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -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; diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index 56695c441514..95a3819dd85d 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -551,16 +551,11 @@ 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 { @@ -568,6 +563,13 @@ 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; if ((lose++ & 7) == 7) { @@ -578,7 +580,6 @@ 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 @@ -589,7 +590,11 @@ 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 { @@ -597,11 +602,6 @@ 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) { diff --git a/net/rxrpc/proc.c b/net/rxrpc/proc.c index 1f1387cf62c8..aab392b4281f 100644 --- a/net/rxrpc/proc.c +++ b/net/rxrpc/proc.c @@ -476,10 +476,11 @@ 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),