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c410bf0193
rxrpc currently uses a fixed 4s retransmission timeout until the RTT is
sufficiently sampled. This can cause problems with some fileservers with
calls to the cache manager in the afs filesystem being dropped from the
fileserver because a packet goes missing and the retransmission timeout is
greater than the call expiry timeout.
Fix this by:
(1) Copying the RTT/RTO calculation code from Linux's TCP implementation
and altering it to fit rxrpc.
(2) Altering the various users of the RTT to make use of the new SRTT
value.
(3) Replacing the use of rxrpc_resend_timeout to use the calculated RTO
value instead (which is needed in jiffies), along with a backoff.
Notes:
(1) rxrpc provides RTT samples by matching the serial numbers on outgoing
DATA packets that have the RXRPC_REQUEST_ACK set and PING ACK packets
against the reference serial number in incoming REQUESTED ACK and
PING-RESPONSE ACK packets.
(2) Each packet that is transmitted on an rxrpc connection gets a new
per-connection serial number, even for retransmissions, so an ACK can
be cross-referenced to a specific trigger packet. This allows RTT
information to be drawn from retransmitted DATA packets also.
(3) rxrpc maintains the RTT/RTO state on the rxrpc_peer record rather than
on an rxrpc_call because many RPC calls won't live long enough to
generate more than one sample.
(4) The calculated SRTT value is in units of 8ths of a microsecond rather
than nanoseconds.
The (S)RTT and RTO values are displayed in /proc/net/rxrpc/peers.
Fixes: 17926a7932 ([AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both"")
Signed-off-by: David Howells <dhowells@redhat.com>
76 lines
2.6 KiB
C
76 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/* RxRPC kernel service interface definitions
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#ifndef _NET_RXRPC_H
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#define _NET_RXRPC_H
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#include <linux/rxrpc.h>
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#include <linux/ktime.h>
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struct key;
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struct sock;
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struct socket;
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struct rxrpc_call;
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enum rxrpc_interruptibility {
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RXRPC_INTERRUPTIBLE, /* Call is interruptible */
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RXRPC_PREINTERRUPTIBLE, /* Call can be cancelled whilst waiting for a slot */
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RXRPC_UNINTERRUPTIBLE, /* Call should not be interruptible at all */
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};
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/*
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* Debug ID counter for tracing.
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*/
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extern atomic_t rxrpc_debug_id;
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typedef void (*rxrpc_notify_rx_t)(struct sock *, struct rxrpc_call *,
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unsigned long);
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typedef void (*rxrpc_notify_end_tx_t)(struct sock *, struct rxrpc_call *,
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unsigned long);
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typedef void (*rxrpc_notify_new_call_t)(struct sock *, struct rxrpc_call *,
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unsigned long);
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typedef void (*rxrpc_discard_new_call_t)(struct rxrpc_call *, unsigned long);
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typedef void (*rxrpc_user_attach_call_t)(struct rxrpc_call *, unsigned long);
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void rxrpc_kernel_new_call_notification(struct socket *,
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rxrpc_notify_new_call_t,
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rxrpc_discard_new_call_t);
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struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *,
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struct sockaddr_rxrpc *,
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struct key *,
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unsigned long,
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s64,
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gfp_t,
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rxrpc_notify_rx_t,
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bool,
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enum rxrpc_interruptibility,
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unsigned int);
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int rxrpc_kernel_send_data(struct socket *, struct rxrpc_call *,
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struct msghdr *, size_t,
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rxrpc_notify_end_tx_t);
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int rxrpc_kernel_recv_data(struct socket *, struct rxrpc_call *,
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struct iov_iter *, bool, u32 *, u16 *);
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bool rxrpc_kernel_abort_call(struct socket *, struct rxrpc_call *,
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u32, int, const char *);
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void rxrpc_kernel_end_call(struct socket *, struct rxrpc_call *);
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void rxrpc_kernel_get_peer(struct socket *, struct rxrpc_call *,
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struct sockaddr_rxrpc *);
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u32 rxrpc_kernel_get_srtt(struct socket *, struct rxrpc_call *);
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int rxrpc_kernel_charge_accept(struct socket *, rxrpc_notify_rx_t,
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rxrpc_user_attach_call_t, unsigned long, gfp_t,
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unsigned int);
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void rxrpc_kernel_set_tx_length(struct socket *, struct rxrpc_call *, s64);
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bool rxrpc_kernel_check_life(const struct socket *, const struct rxrpc_call *);
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u32 rxrpc_kernel_get_epoch(struct socket *, struct rxrpc_call *);
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bool rxrpc_kernel_get_reply_time(struct socket *, struct rxrpc_call *,
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ktime_t *);
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bool rxrpc_kernel_call_is_complete(struct rxrpc_call *);
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void rxrpc_kernel_set_max_life(struct socket *, struct rxrpc_call *,
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unsigned long);
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#endif /* _NET_RXRPC_H */
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