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![David Howells](/assets/img/avatar_default.png)
Now that rxrpc_put_local() may call kthread_stop(), it can't be called
under spinlock as it might sleep. This can cause a problem in the peer
keepalive code in rxrpc as it tries to avoid dropping the peer_hash_lock
from the point it needs to re-add peer->keepalive_link to going round the
loop again in rxrpc_peer_keepalive_dispatch().
Fix this by just dropping the lock when we don't need it and accepting that
we'll have to take it again. This code is only called about every 20s for
each peer, so not very often.
This allows rxrpc_put_peer_unlocked() to be removed also.
If triggered, this bug produces an oops like the following, as reproduced
by a syzbot reproducer for a different oops[1]:
BUG: sleeping function called from invalid context at kernel/sched/completion.c:101
...
RCU nest depth: 0, expected: 0
3 locks held by kworker/u9:0/50:
#0: ffff88810e74a138 ((wq_completion)krxrpcd){+.+.}-{0:0}, at: process_one_work+0x294/0x636
#1: ffff8881013a7e20 ((work_completion)(&rxnet->peer_keepalive_work)){+.+.}-{0:0}, at: process_one_work+0x294/0x636
#2: ffff88817d366390 (&rxnet->peer_hash_lock){+.+.}-{2:2}, at: rxrpc_peer_keepalive_dispatch+0x2bd/0x35f
...
Call Trace:
<TASK>
dump_stack_lvl+0x4c/0x5f
__might_resched+0x2cf/0x2f2
__wait_for_common+0x87/0x1e8
kthread_stop+0x14d/0x255
rxrpc_peer_keepalive_dispatch+0x333/0x35f
rxrpc_peer_keepalive_worker+0x2e9/0x449
process_one_work+0x3c1/0x636
worker_thread+0x25f/0x359
kthread+0x1a6/0x1b5
ret_from_fork+0x1f/0x30
Fixes: a275da62e8
("rxrpc: Create a per-local endpoint receive queue and I/O thread")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/0000000000002b4a9f05ef2b616f@google.com/ [1]
Signed-off-by: David S. Miller <davem@davemloft.net>
349 lines
8.8 KiB
C
349 lines
8.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Peer event handling, typically ICMP messages.
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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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#include <linux/module.h>
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#include <linux/net.h>
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#include <linux/skbuff.h>
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#include <linux/errqueue.h>
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#include <linux/udp.h>
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#include <linux/in.h>
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#include <linux/in6.h>
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#include <linux/icmp.h>
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#include <net/sock.h>
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#include <net/af_rxrpc.h>
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#include <net/ip.h>
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#include "ar-internal.h"
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static void rxrpc_store_error(struct rxrpc_peer *, struct sk_buff *);
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static void rxrpc_distribute_error(struct rxrpc_peer *, struct sk_buff *,
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enum rxrpc_call_completion, int);
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/*
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* Find the peer associated with a local error.
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*/
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static struct rxrpc_peer *rxrpc_lookup_peer_local_rcu(struct rxrpc_local *local,
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const struct sk_buff *skb,
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struct sockaddr_rxrpc *srx)
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{
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struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
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_enter("");
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memset(srx, 0, sizeof(*srx));
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srx->transport_type = local->srx.transport_type;
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srx->transport_len = local->srx.transport_len;
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srx->transport.family = local->srx.transport.family;
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/* Can we see an ICMP4 packet on an ICMP6 listening socket? and vice
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* versa?
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*/
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switch (srx->transport.family) {
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case AF_INET:
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srx->transport_len = sizeof(srx->transport.sin);
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srx->transport.family = AF_INET;
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srx->transport.sin.sin_port = serr->port;
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switch (serr->ee.ee_origin) {
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case SO_EE_ORIGIN_ICMP:
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memcpy(&srx->transport.sin.sin_addr,
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skb_network_header(skb) + serr->addr_offset,
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sizeof(struct in_addr));
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break;
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case SO_EE_ORIGIN_ICMP6:
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memcpy(&srx->transport.sin.sin_addr,
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skb_network_header(skb) + serr->addr_offset + 12,
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sizeof(struct in_addr));
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break;
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default:
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memcpy(&srx->transport.sin.sin_addr, &ip_hdr(skb)->saddr,
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sizeof(struct in_addr));
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break;
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}
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break;
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#ifdef CONFIG_AF_RXRPC_IPV6
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case AF_INET6:
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switch (serr->ee.ee_origin) {
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case SO_EE_ORIGIN_ICMP6:
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srx->transport.sin6.sin6_port = serr->port;
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memcpy(&srx->transport.sin6.sin6_addr,
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skb_network_header(skb) + serr->addr_offset,
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sizeof(struct in6_addr));
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break;
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case SO_EE_ORIGIN_ICMP:
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srx->transport_len = sizeof(srx->transport.sin);
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srx->transport.family = AF_INET;
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srx->transport.sin.sin_port = serr->port;
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memcpy(&srx->transport.sin.sin_addr,
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skb_network_header(skb) + serr->addr_offset,
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sizeof(struct in_addr));
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break;
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default:
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memcpy(&srx->transport.sin6.sin6_addr,
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&ipv6_hdr(skb)->saddr,
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sizeof(struct in6_addr));
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break;
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}
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break;
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#endif
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default:
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BUG();
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}
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return rxrpc_lookup_peer_rcu(local, srx);
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}
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/*
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* Handle an MTU/fragmentation problem.
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*/
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static void rxrpc_adjust_mtu(struct rxrpc_peer *peer, unsigned int mtu)
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{
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/* wind down the local interface MTU */
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if (mtu > 0 && peer->if_mtu == 65535 && mtu < peer->if_mtu)
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peer->if_mtu = mtu;
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if (mtu == 0) {
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/* they didn't give us a size, estimate one */
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mtu = peer->if_mtu;
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if (mtu > 1500) {
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mtu >>= 1;
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if (mtu < 1500)
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mtu = 1500;
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} else {
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mtu -= 100;
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if (mtu < peer->hdrsize)
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mtu = peer->hdrsize + 4;
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}
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}
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if (mtu < peer->mtu) {
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spin_lock(&peer->lock);
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peer->mtu = mtu;
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peer->maxdata = peer->mtu - peer->hdrsize;
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spin_unlock(&peer->lock);
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}
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}
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/*
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* Handle an error received on the local endpoint.
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*/
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void rxrpc_input_error(struct rxrpc_local *local, struct sk_buff *skb)
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{
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struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
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struct sockaddr_rxrpc srx;
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struct rxrpc_peer *peer = NULL;
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_enter("L=%x", local->debug_id);
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if (!skb->len && serr->ee.ee_origin == SO_EE_ORIGIN_TIMESTAMPING) {
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_leave("UDP empty message");
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return;
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}
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rcu_read_lock();
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peer = rxrpc_lookup_peer_local_rcu(local, skb, &srx);
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if (peer && !rxrpc_get_peer_maybe(peer, rxrpc_peer_get_input_error))
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peer = NULL;
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rcu_read_unlock();
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if (!peer)
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return;
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trace_rxrpc_rx_icmp(peer, &serr->ee, &srx);
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if ((serr->ee.ee_origin == SO_EE_ORIGIN_ICMP &&
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serr->ee.ee_type == ICMP_DEST_UNREACH &&
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serr->ee.ee_code == ICMP_FRAG_NEEDED)) {
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rxrpc_adjust_mtu(peer, serr->ee.ee_info);
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goto out;
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}
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rxrpc_store_error(peer, skb);
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out:
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rxrpc_put_peer(peer, rxrpc_peer_put_input_error);
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}
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/*
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* Map an error report to error codes on the peer record.
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*/
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static void rxrpc_store_error(struct rxrpc_peer *peer, struct sk_buff *skb)
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{
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enum rxrpc_call_completion compl = RXRPC_CALL_NETWORK_ERROR;
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struct sock_exterr_skb *serr = SKB_EXT_ERR(skb);
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struct sock_extended_err *ee = &serr->ee;
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int err = ee->ee_errno;
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_enter("");
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switch (ee->ee_origin) {
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case SO_EE_ORIGIN_NONE:
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case SO_EE_ORIGIN_LOCAL:
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compl = RXRPC_CALL_LOCAL_ERROR;
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break;
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case SO_EE_ORIGIN_ICMP6:
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if (err == EACCES)
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err = EHOSTUNREACH;
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fallthrough;
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case SO_EE_ORIGIN_ICMP:
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default:
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break;
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}
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rxrpc_distribute_error(peer, skb, compl, err);
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}
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/*
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* Distribute an error that occurred on a peer.
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*/
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static void rxrpc_distribute_error(struct rxrpc_peer *peer, struct sk_buff *skb,
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enum rxrpc_call_completion compl, int err)
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{
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struct rxrpc_call *call;
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HLIST_HEAD(error_targets);
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spin_lock(&peer->lock);
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hlist_move_list(&peer->error_targets, &error_targets);
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while (!hlist_empty(&error_targets)) {
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call = hlist_entry(error_targets.first,
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struct rxrpc_call, error_link);
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hlist_del_init(&call->error_link);
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spin_unlock(&peer->lock);
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rxrpc_see_call(call, rxrpc_call_see_distribute_error);
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rxrpc_set_call_completion(call, compl, 0, -err);
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rxrpc_input_call_event(call, skb);
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spin_lock(&peer->lock);
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}
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spin_unlock(&peer->lock);
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}
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/*
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* Perform keep-alive pings.
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*/
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static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet,
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struct list_head *collector,
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time64_t base,
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u8 cursor)
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{
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struct rxrpc_peer *peer;
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const u8 mask = ARRAY_SIZE(rxnet->peer_keepalive) - 1;
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time64_t keepalive_at;
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bool use;
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int slot;
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spin_lock(&rxnet->peer_hash_lock);
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while (!list_empty(collector)) {
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peer = list_entry(collector->next,
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struct rxrpc_peer, keepalive_link);
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list_del_init(&peer->keepalive_link);
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if (!rxrpc_get_peer_maybe(peer, rxrpc_peer_get_keepalive))
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continue;
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use = __rxrpc_use_local(peer->local, rxrpc_local_use_peer_keepalive);
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spin_unlock(&rxnet->peer_hash_lock);
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if (use) {
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keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME;
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slot = keepalive_at - base;
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_debug("%02x peer %u t=%d {%pISp}",
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cursor, peer->debug_id, slot, &peer->srx.transport);
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if (keepalive_at <= base ||
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keepalive_at > base + RXRPC_KEEPALIVE_TIME) {
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rxrpc_send_keepalive(peer);
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slot = RXRPC_KEEPALIVE_TIME;
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}
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/* A transmission to this peer occurred since last we
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* examined it so put it into the appropriate future
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* bucket.
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*/
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slot += cursor;
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slot &= mask;
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spin_lock(&rxnet->peer_hash_lock);
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list_add_tail(&peer->keepalive_link,
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&rxnet->peer_keepalive[slot & mask]);
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spin_unlock(&rxnet->peer_hash_lock);
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rxrpc_unuse_local(peer->local, rxrpc_local_unuse_peer_keepalive);
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}
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rxrpc_put_peer(peer, rxrpc_peer_put_keepalive);
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spin_lock(&rxnet->peer_hash_lock);
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}
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spin_unlock(&rxnet->peer_hash_lock);
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}
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/*
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* Perform keep-alive pings with VERSION packets to keep any NAT alive.
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*/
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void rxrpc_peer_keepalive_worker(struct work_struct *work)
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{
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struct rxrpc_net *rxnet =
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container_of(work, struct rxrpc_net, peer_keepalive_work);
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const u8 mask = ARRAY_SIZE(rxnet->peer_keepalive) - 1;
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time64_t base, now, delay;
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u8 cursor, stop;
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LIST_HEAD(collector);
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now = ktime_get_seconds();
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base = rxnet->peer_keepalive_base;
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cursor = rxnet->peer_keepalive_cursor;
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_enter("%lld,%u", base - now, cursor);
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if (!rxnet->live)
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return;
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/* Remove to a temporary list all the peers that are currently lodged
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* in expired buckets plus all new peers.
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*
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* Everything in the bucket at the cursor is processed this
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* second; the bucket at cursor + 1 goes at now + 1s and so
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* on...
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*/
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spin_lock(&rxnet->peer_hash_lock);
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list_splice_init(&rxnet->peer_keepalive_new, &collector);
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stop = cursor + ARRAY_SIZE(rxnet->peer_keepalive);
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while (base <= now && (s8)(cursor - stop) < 0) {
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list_splice_tail_init(&rxnet->peer_keepalive[cursor & mask],
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&collector);
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base++;
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cursor++;
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}
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base = now;
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spin_unlock(&rxnet->peer_hash_lock);
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rxnet->peer_keepalive_base = base;
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rxnet->peer_keepalive_cursor = cursor;
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rxrpc_peer_keepalive_dispatch(rxnet, &collector, base, cursor);
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ASSERT(list_empty(&collector));
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/* Schedule the timer for the next occupied timeslot. */
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cursor = rxnet->peer_keepalive_cursor;
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stop = cursor + RXRPC_KEEPALIVE_TIME - 1;
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for (; (s8)(cursor - stop) < 0; cursor++) {
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if (!list_empty(&rxnet->peer_keepalive[cursor & mask]))
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break;
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base++;
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}
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now = ktime_get_seconds();
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delay = base - now;
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if (delay < 1)
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delay = 1;
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delay *= HZ;
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if (rxnet->live)
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timer_reduce(&rxnet->peer_keepalive_timer, jiffies + delay);
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_leave("");
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}
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