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3cec055c56
linux/net/rxrpc/proc.c
David Howells 3cec055c56 rxrpc: Don't hold a ref for connection workqueue 
Currently, rxrpc gives the connection's work item a ref on the connection
when it queues it - and this is called from the timer expiration function.
The problem comes when queue_work() fails (ie. the work item is already
queued): the timer routine must put the ref - but this may cause the
cleanup code to run.

This has the unfortunate effect that the cleanup code may then be run in
softirq context - which means that any spinlocks it might need to touch
have to be guarded to disable softirqs (ie. they need a "_bh" suffix).

 (1) Don't give a ref to the work item.

 (2) Simplify handling of service connections by adding a separate active
     count so that the refcount isn't also used for this.

 (3) Connection destruction for both client and service connections can
     then be cleaned up by putting rxrpc_put_connection() out of line and
     making a tidy progression through the destruction code (offloaded to a
     workqueue if put from softirq or processor function context).  The RCU
     part of the cleanup then only deals with the freeing at the end.

 (4) Make rxrpc_queue_conn() return immediately if it sees the active count
     is -1 rather then queuing the connection.

 (5) Make sure that the cleanup routine waits for the work item to
     complete.

 (6) Stash the rxrpc_net pointer in the conn struct so that the rcu free
     routine can use it, even if the local endpoint has been freed.

Unfortunately, neither the timer nor the work item can simply get around
the problem by just using refcount_inc_not_zero() as the waits would still
have to be done, and there would still be the possibility of having to put
the ref in the expiration function.

Note the connection work item is mostly going to go away with the main
event work being transferred to the I/O thread, so the wait in (6) will
become obsolete.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
2022-12-01 13:36:40 +00:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/* /proc/net/ support for AF_RXRPC
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/module.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"
static const char *const rxrpc_conn_states[RXRPC_CONN__NR_STATES] = {
[RXRPC_CONN_UNUSED] = "Unused ",
[RXRPC_CONN_CLIENT] = "Client ",
[RXRPC_CONN_SERVICE_PREALLOC] = "SvPrealc",
[RXRPC_CONN_SERVICE_UNSECURED] = "SvUnsec ",
[RXRPC_CONN_SERVICE_CHALLENGING] = "SvChall ",
[RXRPC_CONN_SERVICE] = "SvSecure",
[RXRPC_CONN_REMOTELY_ABORTED] = "RmtAbort",
[RXRPC_CONN_LOCALLY_ABORTED] = "LocAbort",
};
/*
* generate a list of extant and dead calls in /proc/net/rxrpc_calls
*/
static void *rxrpc_call_seq_start(struct seq_file *seq, loff_t *_pos)
__acquires(rcu)
{
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
rcu_read_lock();
return seq_list_start_head_rcu(&rxnet->calls, *_pos);
}
static void *rxrpc_call_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
return seq_list_next_rcu(v, &rxnet->calls, pos);
}
static void rxrpc_call_seq_stop(struct seq_file *seq, void *v)
__releases(rcu)
{
rcu_read_unlock();
}
static int rxrpc_call_seq_show(struct seq_file *seq, void *v)
{
struct rxrpc_local *local;
struct rxrpc_sock *rx;
struct rxrpc_peer *peer;
struct rxrpc_call *call;
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
unsigned long timeout = 0;
rxrpc_seq_t acks_hard_ack;
char lbuff[50], rbuff[50];
u64 wtmp;
if (v == &rxnet->calls) {
seq_puts(seq,
"Proto Local "
" Remote "
" SvID ConnID CallID End Use State Abort "
" DebugId TxSeq TW RxSeq RW RxSerial RxTimo\n");
return 0;
}
call = list_entry(v, struct rxrpc_call, link);
rx = rcu_dereference(call->socket);
if (rx) {
local = READ_ONCE(rx->local);
if (local)
sprintf(lbuff, "%pISpc", &local->srx.transport);
else
strcpy(lbuff, "no_local");
} else {
strcpy(lbuff, "no_socket");
}
peer = call->peer;
if (peer)
sprintf(rbuff, "%pISpc", &peer->srx.transport);
else
strcpy(rbuff, "no_connection");
if (call->state != RXRPC_CALL_SERVER_PREALLOC) {
timeout = READ_ONCE(call->expect_rx_by);
timeout -= jiffies;
}
acks_hard_ack = READ_ONCE(call->acks_hard_ack);
wtmp = atomic64_read_acquire(&call->ackr_window);
seq_printf(seq,
"UDP %-47.47s %-47.47s %4x %08x %08x %s %3u"
" %-8.8s %08x %08x %08x %02x %08x %02x %08x %06lx\n",
lbuff,
rbuff,
call->service_id,
call->cid,
call->call_id,
rxrpc_is_service_call(call) ? "Svc" : "Clt",
refcount_read(&call->ref),
rxrpc_call_states[call->state],
call->abort_code,
call->debug_id,
acks_hard_ack, READ_ONCE(call->tx_top) - acks_hard_ack,
lower_32_bits(wtmp), upper_32_bits(wtmp) - lower_32_bits(wtmp),
call->rx_serial,
timeout);
return 0;
}
const struct seq_operations rxrpc_call_seq_ops = {
.start = rxrpc_call_seq_start,
.next = rxrpc_call_seq_next,
.stop = rxrpc_call_seq_stop,
.show = rxrpc_call_seq_show,
};
/*
* generate a list of extant virtual connections in /proc/net/rxrpc_conns
*/
static void *rxrpc_connection_seq_start(struct seq_file *seq, loff_t *_pos)
__acquires(rxnet->conn_lock)
{
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
read_lock(&rxnet->conn_lock);
return seq_list_start_head(&rxnet->conn_proc_list, *_pos);
}
static void *rxrpc_connection_seq_next(struct seq_file *seq, void *v,
loff_t *pos)
{
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
return seq_list_next(v, &rxnet->conn_proc_list, pos);
}
static void rxrpc_connection_seq_stop(struct seq_file *seq, void *v)
__releases(rxnet->conn_lock)
{
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
read_unlock(&rxnet->conn_lock);
}
static int rxrpc_connection_seq_show(struct seq_file *seq, void *v)
{
struct rxrpc_connection *conn;
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
char lbuff[50], rbuff[50];
if (v == &rxnet->conn_proc_list) {
seq_puts(seq,
"Proto Local "
" Remote "
" SvID ConnID End Ref Act State Key "
" Serial ISerial CallId0 CallId1 CallId2 CallId3\n"
);
return 0;
}
conn = list_entry(v, struct rxrpc_connection, proc_link);
if (conn->state == RXRPC_CONN_SERVICE_PREALLOC) {
strcpy(lbuff, "no_local");
strcpy(rbuff, "no_connection");
goto print;
}
sprintf(lbuff, "%pISpc", &conn->local->srx.transport);
sprintf(rbuff, "%pISpc", &conn->peer->srx.transport);
print:
seq_printf(seq,
"UDP %-47.47s %-47.47s %4x %08x %s %3u %3d"
" %s %08x %08x %08x %08x %08x %08x %08x\n",
lbuff,
rbuff,
conn->service_id,
conn->proto.cid,
rxrpc_conn_is_service(conn) ? "Svc" : "Clt",
refcount_read(&conn->ref),
atomic_read(&conn->active),
rxrpc_conn_states[conn->state],
key_serial(conn->key),
atomic_read(&conn->serial),
conn->hi_serial,
conn->channels[0].call_id,
conn->channels[1].call_id,
conn->channels[2].call_id,
conn->channels[3].call_id);
return 0;
}
const struct seq_operations rxrpc_connection_seq_ops = {
.start = rxrpc_connection_seq_start,
.next = rxrpc_connection_seq_next,
.stop = rxrpc_connection_seq_stop,
.show = rxrpc_connection_seq_show,
};
/*
* generate a list of extant virtual peers in /proc/net/rxrpc/peers
*/
static int rxrpc_peer_seq_show(struct seq_file *seq, void *v)
{
struct rxrpc_peer *peer;
time64_t now;
char lbuff[50], rbuff[50];
if (v == SEQ_START_TOKEN) {
seq_puts(seq,
"Proto Local "
" Remote "
" Use SST MTU LastUse RTT RTO\n"
);
return 0;
}
peer = list_entry(v, struct rxrpc_peer, hash_link);
sprintf(lbuff, "%pISpc", &peer->local->srx.transport);
sprintf(rbuff, "%pISpc", &peer->srx.transport);
now = ktime_get_seconds();
seq_printf(seq,
"UDP %-47.47s %-47.47s %3u"
" %3u %5u %6llus %8u %8u\n",
lbuff,
rbuff,
refcount_read(&peer->ref),
peer->cong_ssthresh,
peer->mtu,
now - peer->last_tx_at,
peer->srtt_us >> 3,
jiffies_to_usecs(peer->rto_j));
return 0;
}
static void *rxrpc_peer_seq_start(struct seq_file *seq, loff_t *_pos)
__acquires(rcu)
{
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
unsigned int bucket, n;
unsigned int shift = 32 - HASH_BITS(rxnet->peer_hash);
void *p;
rcu_read_lock();
if (*_pos >= UINT_MAX)
return NULL;
n = *_pos & ((1U << shift) - 1);
bucket = *_pos >> shift;
for (;;) {
if (bucket >= HASH_SIZE(rxnet->peer_hash)) {
*_pos = UINT_MAX;
return NULL;
}
if (n == 0) {
if (bucket == 0)
return SEQ_START_TOKEN;
*_pos += 1;
n++;
}
p = seq_hlist_start_rcu(&rxnet->peer_hash[bucket], n - 1);
if (p)
return p;
bucket++;
n = 1;
*_pos = (bucket << shift) | n;
}
}
static void *rxrpc_peer_seq_next(struct seq_file *seq, void *v, loff_t *_pos)
{
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
unsigned int bucket, n;
unsigned int shift = 32 - HASH_BITS(rxnet->peer_hash);
void *p;
if (*_pos >= UINT_MAX)
return NULL;
bucket = *_pos >> shift;
p = seq_hlist_next_rcu(v, &rxnet->peer_hash[bucket], _pos);
if (p)
return p;
for (;;) {
bucket++;
n = 1;
*_pos = (bucket << shift) | n;
if (bucket >= HASH_SIZE(rxnet->peer_hash)) {
*_pos = UINT_MAX;
return NULL;
}
if (n == 0) {
*_pos += 1;
n++;
}
p = seq_hlist_start_rcu(&rxnet->peer_hash[bucket], n - 1);
if (p)
return p;
}
}
static void rxrpc_peer_seq_stop(struct seq_file *seq, void *v)
__releases(rcu)
{
rcu_read_unlock();
}
const struct seq_operations rxrpc_peer_seq_ops = {
.start = rxrpc_peer_seq_start,
.next = rxrpc_peer_seq_next,
.stop = rxrpc_peer_seq_stop,
.show = rxrpc_peer_seq_show,
};
/*
* Generate a list of extant virtual local endpoints in /proc/net/rxrpc/locals
*/
static int rxrpc_local_seq_show(struct seq_file *seq, void *v)
{
struct rxrpc_local *local;
char lbuff[50];
if (v == SEQ_START_TOKEN) {
seq_puts(seq,
"Proto Local "
" Use Act\n");
return 0;
}
local = hlist_entry(v, struct rxrpc_local, link);
sprintf(lbuff, "%pISpc", &local->srx.transport);
seq_printf(seq,
"UDP %-47.47s %3u %3u\n",
lbuff,
refcount_read(&local->ref),
atomic_read(&local->active_users));
return 0;
}
static void *rxrpc_local_seq_start(struct seq_file *seq, loff_t *_pos)
__acquires(rcu)
{
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
unsigned int n;
rcu_read_lock();
if (*_pos >= UINT_MAX)
return NULL;
n = *_pos;
if (n == 0)
return SEQ_START_TOKEN;
return seq_hlist_start_rcu(&rxnet->local_endpoints, n - 1);
}
static void *rxrpc_local_seq_next(struct seq_file *seq, void *v, loff_t *_pos)
{
struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
if (*_pos >= UINT_MAX)
return NULL;
return seq_hlist_next_rcu(v, &rxnet->local_endpoints, _pos);
}
static void rxrpc_local_seq_stop(struct seq_file *seq, void *v)
__releases(rcu)
{
rcu_read_unlock();
}
const struct seq_operations rxrpc_local_seq_ops = {
.start = rxrpc_local_seq_start,
.next = rxrpc_local_seq_next,
.stop = rxrpc_local_seq_stop,
.show = rxrpc_local_seq_show,
};
/*
* Display stats in /proc/net/rxrpc/stats
*/
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\n",
atomic_read(&rxnet->stat_tx_data_send),
atomic_read(&rxnet->stat_tx_data_send_frag));
seq_printf(seq,
"Data-Tx : nr=%u retrans=%u\n",
atomic_read(&rxnet->stat_tx_data),
atomic_read(&rxnet->stat_tx_data_retrans));
seq_printf(seq,
"Data-Rx : nr=%u reqack=%u jumbo=%u\n",
atomic_read(&rxnet->stat_rx_data),
atomic_read(&rxnet->stat_rx_data_reqack),
atomic_read(&rxnet->stat_rx_data_jumbo));
seq_printf(seq,
"Ack : fill=%u send=%u skip=%u\n",
atomic_read(&rxnet->stat_tx_ack_fill),
atomic_read(&rxnet->stat_tx_ack_send),
atomic_read(&rxnet->stat_tx_ack_skip));
seq_printf(seq,
"Ack-Tx : req=%u dup=%u oos=%u exw=%u nos=%u png=%u prs=%u dly=%u idl=%u\n",
atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_REQUESTED]),
atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_DUPLICATE]),
atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_OUT_OF_SEQUENCE]),
atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_EXCEEDS_WINDOW]),
atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_NOSPACE]),
atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_PING]),
atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_PING_RESPONSE]),
atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_DELAY]),
atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_IDLE]));
seq_printf(seq,
"Ack-Rx : req=%u dup=%u oos=%u exw=%u nos=%u png=%u prs=%u dly=%u idl=%u\n",
atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_REQUESTED]),
atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_DUPLICATE]),
atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_OUT_OF_SEQUENCE]),
atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_EXCEEDS_WINDOW]),
atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_NOSPACE]),
atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_PING]),
atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_PING_RESPONSE]),
atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_DELAY]),
atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_IDLE]));
seq_printf(seq,
"Why-Req-A: acklost=%u already=%u mrtt=%u ortt=%u\n",
atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_ack_lost]),
atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_already_on]),
atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_more_rtt]),
atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_old_rtt]));
seq_printf(seq,
"Why-Req-A: nolast=%u retx=%u slows=%u smtxw=%u\n",
atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_no_srv_last]),
atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_retrans]),
atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_slow_start]),
atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_small_txwin]));
seq_printf(seq,
"Buffers : txb=%u rxb=%u\n",
atomic_read(&rxrpc_nr_txbuf),
atomic_read(&rxrpc_n_rx_skbs));
return 0;
}
/*
* Clear stats if /proc/net/rxrpc/stats is written to.
*/
int rxrpc_stats_clear(struct file *file, char *buf, size_t size)
{
struct seq_file *m = file->private_data;
struct rxrpc_net *rxnet = rxrpc_net(seq_file_single_net(m));
if (size > 1 || (size == 1 && buf[0] != '\n'))
return -EINVAL;
atomic_set(&rxnet->stat_tx_data, 0);
atomic_set(&rxnet->stat_tx_data_retrans, 0);
atomic_set(&rxnet->stat_tx_data_send, 0);
atomic_set(&rxnet->stat_tx_data_send_frag, 0);
atomic_set(&rxnet->stat_rx_data, 0);
atomic_set(&rxnet->stat_rx_data_reqack, 0);
atomic_set(&rxnet->stat_rx_data_jumbo, 0);
atomic_set(&rxnet->stat_tx_ack_fill, 0);
atomic_set(&rxnet->stat_tx_ack_send, 0);
atomic_set(&rxnet->stat_tx_ack_skip, 0);
memset(&rxnet->stat_tx_acks, 0, sizeof(rxnet->stat_tx_acks));
memset(&rxnet->stat_rx_acks, 0, sizeof(rxnet->stat_rx_acks));
memset(&rxnet->stat_why_req_ack, 0, sizeof(rxnet->stat_why_req_ack));
return size;
}
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