wireguard-linux/net/rxrpc/output.c, branch jd/orphan-parallel

rxrpc: Rewrite the client connection manager

2020-09-08T20:11:43Z

Rewrite the rxrpc client connection manager so that it can support multiple connections for a given security key to a peer. The following changes are made: (1) For each open socket, the code currently maintains an rbtree with the connections placed into it, keyed by communications parameters. This is tricky to maintain as connections can be culled from the tree or replaced within it. Connections can require replacement for a number of reasons, e.g. their IDs span too great a range for the IDR data type to represent efficiently, the call ID numbers on that conn would overflow or the conn got aborted. This is changed so that there's now a connection bundle object placed in the tree, keyed on the same parameters. The bundle, however, does not need to be replaced. (2) An rxrpc_bundle object can now manage the available channels for a set of parallel connections. The lock that manages this is moved there from the rxrpc_connection struct (channel_lock). (3) There'a a dummy bundle for all incoming connections to share so that they have a channel_lock too. It might be better to give each incoming connection its own bundle. This bundle is not needed to manage which channels incoming calls are made on because that's the solely at whim of the client. (4) The restrictions on how many client connections are around are removed. Instead, a previous patch limits the number of client calls that can be allocated. Ordinarily, client connections are reaped after 2 minutes on the idle queue, but when more than a certain number of connections are in existence, the reaper starts reaping them after 2s of idleness instead to get the numbers back down. It could also be made such that new call allocations are forced to wait until the number of outstanding connections subsides. Signed-off-by: David Howells

rxrpc: Fix loss of RTT samples due to interposed ACK

2020-08-20T16:59:27Z

The Rx protocol has a mechanism to help generate RTT samples that works by a client transmitting a REQUESTED-type ACK when it receives a DATA packet that has the REQUEST_ACK flag set. The peer, however, may interpose other ACKs before transmitting the REQUESTED-ACK, as can be seen in the following trace excerpt: rxrpc_tx_data: c=00000044 DATA d0b5ece8:00000001 00000001 q=00000001 fl=07 rxrpc_rx_ack: c=00000044 00000001 PNG r=00000000 f=00000002 p=00000000 n=0 rxrpc_rx_ack: c=00000044 00000002 REQ r=00000001 f=00000002 p=00000001 n=0 ... DATA packet 1 (q=xx) has REQUEST_ACK set (bit 1 of fl=xx). The incoming ping (labelled PNG) hard-acks the request DATA packet (f=xx exceeds the sequence number of the DATA packet), causing it to be discarded from the Tx ring. The ACK that was requested (labelled REQ, r=xx references the serial of the DATA packet) comes after the ping, but the sk_buff holding the timestamp has gone and the RTT sample is lost. This is particularly noticeable on RPC calls used to probe the service offered by the peer. A lot of peers end up with an unknown RTT because we only ever sent a single RPC. This confuses the server rotation algorithm. Fix this by caching the information about the outgoing packet in RTT calculations in the rxrpc_call struct rather than looking in the Tx ring. A four-deep buffer is maintained and both REQUEST_ACK-flagged DATA and PING-ACK transmissions are recorded in there. When the appropriate response ACK is received, the buffer is checked for a match and, if found, an RTT sample is recorded. If a received ACK refers to a packet with a later serial number than an entry in the cache, that entry is presumed lost and the entry is made available to record a new transmission. ACKs types other than REQUESTED-type and PING-type cause any matching sample to be cancelled as they don't necessarily represent a useful measurement. If there's no space in the buffer on ping/data transmission, the sample base is discarded. Fixes: 50235c4b5a2f ("rxrpc: Obtain RTT data by requesting ACKs on DATA packets") Signed-off-by: David Howells

ipv4: add ip_sock_set_mtu_discover

2020-05-28T18:11:45Z

Add a helper to directly set the IP_MTU_DISCOVER sockopt from kernel space without going through a fake uaccess. Signed-off-by: Christoph Hellwig Reviewed-by: David Howells [rxrpc bits] Signed-off-by: David S. Miller

rxrpc: Fix the excessive initial retransmission timeout

2020-05-11T15:42:28Z

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: 17926a79320a ([AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both"") Signed-off-by: David Howells

rxrpc: Fix DATA Tx to disable nofrag for UDP on AF_INET6 socket

2020-04-14T23:26:47Z

Fix the DATA packet transmission to disable nofrag for UDPv4 on an AF_INET6 socket as well as UDPv6 when trying to transmit fragmentably. Without this, packets filled to the normal size used by the kernel AFS client of 1412 bytes be rejected by udp_sendmsg() with EMSGSIZE immediately. The ->sk_error_report() notification hook is called, but rxrpc doesn't generate a trace for it. This is a temporary fix; a more permanent solution needs to involve changing the size of the packets being filled in accordance with the MTU, which isn't currently done in AF_RXRPC. The reason for not doing so was that, barring the last packet in an rx jumbo packet, jumbos can only be assembled out of 1412-byte packets - and the plan was to construct jumbos on the fly at transmission time. Also, there's no point turning on IPV6_MTU_DISCOVER, since IPv6 has to engage in this anyway since fragmentation is only done by the sender. We can then condense the switch-statement in rxrpc_send_data_packet(). Fixes: 75b54cb57ca3 ("rxrpc: Add IPv6 support") Signed-off-by: David Howells Signed-off-by: David S. Miller

rxrpc: Fix NULL pointer deref due to call->conn being cleared on disconnect

2020-02-03T10:25:30Z

When a call is disconnected, the connection pointer from the call is cleared to make sure it isn't used again and to prevent further attempted transmission for the call. Unfortunately, there might be a daemon trying to use it at the same time to transmit a packet. Fix this by keeping call->conn set, but setting a flag on the call to indicate disconnection instead. Remove also the bits in the transmission functions where the conn pointer is checked and a ref taken under spinlock as this is now redundant. Fixes: 8d94aa381dab ("rxrpc: Calls shouldn't hold socket refs") Signed-off-by: David Howells

rxrpc: Use the tx-phase skb flag to simplify tracing

2019-08-27T09:04:18Z

Use the previously-added transmit-phase skbuff private flag to simplify the socket buffer tracing a bit. Which phase the skbuff comes from can now be divined from the skb rather than having to be guessed from the call state. We can also reduce the number of rxrpc_skb_trace values by eliminating the difference between Tx and Rx in the symbols. Signed-off-by: David Howells

rxrpc: Don't bother generating maxSkew in the ACK packet

2019-08-09T14:24:00Z

Don't bother generating maxSkew in the ACK packet as it has been obsolete since AFS 3.1. Signed-off-by: David Howells Reviewed-by: Jeffrey Altman

rxrpc: Fix uninitialized error code in rxrpc_send_data_packet()

2019-07-02T19:09:09Z

With gcc 4.1: net/rxrpc/output.c: In function ‘rxrpc_send_data_packet’: net/rxrpc/output.c:338: warning: ‘ret’ may be used uninitialized in this function Indeed, if the first jump to the send_fragmentable label is made, and the address family is not handled in the switch() statement, ret will be used uninitialized. Fix this by BUG()'ing as is done in other places in rxrpc where internal support for future address families will need adding. It should not be possible to reach this normally as the address families are checked up-front. Fixes: 5a924b8951f835b5 ("rxrpc: Don't store the rxrpc header in the Tx queue sk_buffs") Reported-by: Geert Uytterhoeven Signed-off-by: David Howells Signed-off-by: David S. Miller

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32Z

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman