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linux/fs/dlm/lowcomms.c

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/******************************************************************************
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
** Copyright (C) 2004-2009 Red Hat, Inc. All rights reserved.
**
** This copyrighted material is made available to anyone wishing to use,
** modify, copy, or redistribute it subject to the terms and conditions
** of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/
/*
* lowcomms.c
*
* This is the "low-level" comms layer.
*
* It is responsible for sending/receiving messages
* from other nodes in the cluster.
*
* Cluster nodes are referred to by their nodeids. nodeids are
* simply 32 bit numbers to the locking module - if they need to
* be expanded for the cluster infrastructure then that is its
* responsibility. It is this layer's
* responsibility to resolve these into IP address or
* whatever it needs for inter-node communication.
*
* The comms level is two kernel threads that deal mainly with
* the receiving of messages from other nodes and passing them
* up to the mid-level comms layer (which understands the
* message format) for execution by the locking core, and
* a send thread which does all the setting up of connections
* to remote nodes and the sending of data. Threads are not allowed
* to send their own data because it may cause them to wait in times
* of high load. Also, this way, the sending thread can collect together
* messages bound for one node and send them in one block.
*
* lowcomms will choose to use either TCP or SCTP as its transport layer
* depending on the configuration variable 'protocol'. This should be set
* to 0 (default) for TCP or 1 for SCTP. It should be configured using a
* cluster-wide mechanism as it must be the same on all nodes of the cluster
* for the DLM to function.
*
*/
#include <asm/ioctls.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/mutex.h>
#include <linux/sctp.h>
#include <linux/slab.h>
#include <net/sctp/sctp.h>
#include <net/ipv6.h>
#include "dlm_internal.h"
#include "lowcomms.h"
#include "midcomms.h"
#include "config.h"
#define NEEDED_RMEM (4*1024*1024)
#define CONN_HASH_SIZE 32
/* Number of messages to send before rescheduling */
#define MAX_SEND_MSG_COUNT 25
struct cbuf {
unsigned int base;
unsigned int len;
unsigned int mask;
};
static void cbuf_add(struct cbuf *cb, int n)
{
cb->len += n;
}
static int cbuf_data(struct cbuf *cb)
{
return ((cb->base + cb->len) & cb->mask);
}
static void cbuf_init(struct cbuf *cb, int size)
{
cb->base = cb->len = 0;
cb->mask = size-1;
}
static void cbuf_eat(struct cbuf *cb, int n)
{
cb->len -= n;
cb->base += n;
cb->base &= cb->mask;
}
static bool cbuf_empty(struct cbuf *cb)
{
return cb->len == 0;
}
struct connection {
struct socket *sock; /* NULL if not connected */
uint32_t nodeid; /* So we know who we are in the list */
struct mutex sock_mutex;
unsigned long flags;
#define CF_READ_PENDING 1
#define CF_WRITE_PENDING 2
#define CF_INIT_PENDING 4
#define CF_IS_OTHERCON 5
#define CF_CLOSE 6
#define CF_APP_LIMITED 7
#define CF_CLOSING 8
struct list_head writequeue; /* List of outgoing writequeue_entries */
spinlock_t writequeue_lock;
int (*rx_action) (struct connection *); /* What to do when active */
void (*connect_action) (struct connection *); /* What to do to connect */
struct page *rx_page;
struct cbuf cb;
int retries;
#define MAX_CONNECT_RETRIES 3
struct hlist_node list;
struct connection *othercon;
struct work_struct rwork; /* Receive workqueue */
struct work_struct swork; /* Send workqueue */
};
#define sock2con(x) ((struct connection *)(x)->sk_user_data)
/* An entry waiting to be sent */
struct writequeue_entry {
struct list_head list;
struct page *page;
int offset;
int len;
int end;
int users;
struct connection *con;
};
struct dlm_node_addr {
struct list_head list;
int nodeid;
int addr_count;
int curr_addr_index;
struct sockaddr_storage *addr[DLM_MAX_ADDR_COUNT];
};
static struct listen_sock_callbacks {
void (*sk_error_report)(struct sock *);
void (*sk_data_ready)(struct sock *);
void (*sk_state_change)(struct sock *);
void (*sk_write_space)(struct sock *);
} listen_sock;
static LIST_HEAD(dlm_node_addrs);
static DEFINE_SPINLOCK(dlm_node_addrs_spin);
static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
static int dlm_local_count;
static int dlm_allow_conn;
/* Work queues */
static struct workqueue_struct *recv_workqueue;
static struct workqueue_struct *send_workqueue;
static struct hlist_head connection_hash[CONN_HASH_SIZE];
static DEFINE_MUTEX(connections_lock);
static struct kmem_cache *con_cache;
static void process_recv_sockets(struct work_struct *work);
static void process_send_sockets(struct work_struct *work);
/* This is deliberately very simple because most clusters have simple
sequential nodeids, so we should be able to go straight to a connection
struct in the array */
static inline int nodeid_hash(int nodeid)
{
return nodeid & (CONN_HASH_SIZE-1);
}
static struct connection *__find_con(int nodeid)
{
int r;
struct connection *con;
r = nodeid_hash(nodeid);
hlist_for_each_entry(con, &connection_hash[r], list) {
if (con->nodeid == nodeid)
return con;
}
return NULL;
}
/*
* If 'allocation' is zero then we don't attempt to create a new
* connection structure for this node.
*/
static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
{
struct connection *con = NULL;
int r;
con = __find_con(nodeid);
if (con || !alloc)
return con;
con = kmem_cache_zalloc(con_cache, alloc);
if (!con)
return NULL;
r = nodeid_hash(nodeid);
hlist_add_head(&con->list, &connection_hash[r]);
con->nodeid = nodeid;
mutex_init(&con->sock_mutex);
INIT_LIST_HEAD(&con->writequeue);
spin_lock_init(&con->writequeue_lock);
INIT_WORK(&con->swork, process_send_sockets);
INIT_WORK(&con->rwork, process_recv_sockets);
/* Setup action pointers for child sockets */
if (con->nodeid) {
struct connection *zerocon = __find_con(0);
con->connect_action = zerocon->connect_action;
if (!con->rx_action)
con->rx_action = zerocon->rx_action;
}
return con;
}
/* Loop round all connections */
static void foreach_conn(void (*conn_func)(struct connection *c))
{
int i;
struct hlist_node *n;
struct connection *con;
for (i = 0; i < CONN_HASH_SIZE; i++) {
hlist_for_each_entry_safe(con, n, &connection_hash[i], list)
conn_func(con);
}
}
static struct connection *nodeid2con(int nodeid, gfp_t allocation)
{
struct connection *con;
mutex_lock(&connections_lock);
con = __nodeid2con(nodeid, allocation);
mutex_unlock(&connections_lock);
return con;
}
static struct dlm_node_addr *find_node_addr(int nodeid)
{
struct dlm_node_addr *na;
list_for_each_entry(na, &dlm_node_addrs, list) {
if (na->nodeid == nodeid)
return na;
}
return NULL;
}
static int addr_compare(struct sockaddr_storage *x, struct sockaddr_storage *y)
{
switch (x->ss_family) {
case AF_INET: {
struct sockaddr_in *sinx = (struct sockaddr_in *)x;
struct sockaddr_in *siny = (struct sockaddr_in *)y;
if (sinx->sin_addr.s_addr != siny->sin_addr.s_addr)
return 0;
if (sinx->sin_port != siny->sin_port)
return 0;
break;
}
case AF_INET6: {
struct sockaddr_in6 *sinx = (struct sockaddr_in6 *)x;
struct sockaddr_in6 *siny = (struct sockaddr_in6 *)y;
if (!ipv6_addr_equal(&sinx->sin6_addr, &siny->sin6_addr))
return 0;
if (sinx->sin6_port != siny->sin6_port)
return 0;
break;
}
default:
return 0;
}
return 1;
}
static int nodeid_to_addr(int nodeid, struct sockaddr_storage *sas_out,
struct sockaddr *sa_out, bool try_new_addr)
{
struct sockaddr_storage sas;
struct dlm_node_addr *na;
if (!dlm_local_count)
return -1;
spin_lock(&dlm_node_addrs_spin);
na = find_node_addr(nodeid);
if (na && na->addr_count) {
memcpy(&sas, na->addr[na->curr_addr_index],
sizeof(struct sockaddr_storage));
if (try_new_addr) {
na->curr_addr_index++;
if (na->curr_addr_index == na->addr_count)
na->curr_addr_index = 0;
}
}
spin_unlock(&dlm_node_addrs_spin);
if (!na)
return -EEXIST;
if (!na->addr_count)
return -ENOENT;
if (sas_out)
memcpy(sas_out, &sas, sizeof(struct sockaddr_storage));
if (!sa_out)
return 0;
if (dlm_local_addr[0]->ss_family == AF_INET) {
struct sockaddr_in *in4 = (struct sockaddr_in *) &sas;
struct sockaddr_in *ret4 = (struct sockaddr_in *) sa_out;
ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
} else {
struct sockaddr_in6 *in6 = (struct sockaddr_in6 *) &sas;
struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) sa_out;
ret6->sin6_addr = in6->sin6_addr;
}
return 0;
}
static int addr_to_nodeid(struct sockaddr_storage *addr, int *nodeid)
{
struct dlm_node_addr *na;
int rv = -EEXIST;
int addr_i;
spin_lock(&dlm_node_addrs_spin);
list_for_each_entry(na, &dlm_node_addrs, list) {
if (!na->addr_count)
continue;
for (addr_i = 0; addr_i < na->addr_count; addr_i++) {
if (addr_compare(na->addr[addr_i], addr)) {
*nodeid = na->nodeid;
rv = 0;
goto unlock;
}
}
}
unlock:
spin_unlock(&dlm_node_addrs_spin);
return rv;
}
int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len)
{
struct sockaddr_storage *new_addr;
struct dlm_node_addr *new_node, *na;
new_node = kzalloc(sizeof(struct dlm_node_addr), GFP_NOFS);
if (!new_node)
return -ENOMEM;
new_addr = kzalloc(sizeof(struct sockaddr_storage), GFP_NOFS);
if (!new_addr) {
kfree(new_node);
return -ENOMEM;
}
memcpy(new_addr, addr, len);
spin_lock(&dlm_node_addrs_spin);
na = find_node_addr(nodeid);
if (!na) {
new_node->nodeid = nodeid;
new_node->addr[0] = new_addr;
new_node->addr_count = 1;
list_add(&new_node->list, &dlm_node_addrs);
spin_unlock(&dlm_node_addrs_spin);
return 0;
}
if (na->addr_count >= DLM_MAX_ADDR_COUNT) {
spin_unlock(&dlm_node_addrs_spin);
kfree(new_addr);
kfree(new_node);
return -ENOSPC;
}
na->addr[na->addr_count++] = new_addr;
spin_unlock(&dlm_node_addrs_spin);
kfree(new_node);
return 0;
}
/* Data available on socket or listen socket received a connect */
static void lowcomms_data_ready(struct sock *sk)
{
struct connection *con;
read_lock_bh(&sk->sk_callback_lock);
con = sock2con(sk);
if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
queue_work(recv_workqueue, &con->rwork);
read_unlock_bh(&sk->sk_callback_lock);
}
static void lowcomms_write_space(struct sock *sk)
{
struct connection *con;
read_lock_bh(&sk->sk_callback_lock);
con = sock2con(sk);
if (!con)
goto out;
clear_bit(SOCK_NOSPACE, &con->sock->flags);
if (test_and_clear_bit(CF_APP_LIMITED, &con->flags)) {
con->sock->sk->sk_write_pending--;
clear_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags);
}
queue_work(send_workqueue, &con->swork);
out:
read_unlock_bh(&sk->sk_callback_lock);
}
static inline void lowcomms_connect_sock(struct connection *con)
{
if (test_bit(CF_CLOSE, &con->flags))
return;
queue_work(send_workqueue, &con->swork);
cond_resched();
}
static void lowcomms_state_change(struct sock *sk)
{
/* SCTP layer is not calling sk_data_ready when the connection
* is done, so we catch the signal through here. Also, it
* doesn't switch socket state when entering shutdown, so we
* skip the write in that case.
*/
if (sk->sk_shutdown) {
if (sk->sk_shutdown == RCV_SHUTDOWN)
lowcomms_data_ready(sk);
} else if (sk->sk_state == TCP_ESTABLISHED) {
lowcomms_write_space(sk);
}
}
int dlm_lowcomms_connect_node(int nodeid)
{
struct connection *con;
if (nodeid == dlm_our_nodeid())
return 0;
con = nodeid2con(nodeid, GFP_NOFS);
if (!con)
return -ENOMEM;
lowcomms_connect_sock(con);
return 0;
}
static void lowcomms_error_report(struct sock *sk)
{
struct connection *con;
struct sockaddr_storage saddr;
int buflen;
void (*orig_report)(struct sock *) = NULL;
read_lock_bh(&sk->sk_callback_lock);
con = sock2con(sk);
if (con == NULL)
goto out;
orig_report = listen_sock.sk_error_report;
if (con->sock == NULL ||
kernel_getpeername(con->sock, (struct sockaddr *)&saddr, &buflen)) {
printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
"sending to node %d, port %d, "
"sk_err=%d/%d\n", dlm_our_nodeid(),
con->nodeid, dlm_config.ci_tcp_port,
sk->sk_err, sk->sk_err_soft);
} else if (saddr.ss_family == AF_INET) {
struct sockaddr_in *sin4 = (struct sockaddr_in *)&saddr;
printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
"sending to node %d at %pI4, port %d, "
"sk_err=%d/%d\n", dlm_our_nodeid(),
con->nodeid, &sin4->sin_addr.s_addr,
dlm_config.ci_tcp_port, sk->sk_err,
sk->sk_err_soft);
} else {
struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&saddr;
printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
"sending to node %d at %u.%u.%u.%u, "
"port %d, sk_err=%d/%d\n", dlm_our_nodeid(),
con->nodeid, sin6->sin6_addr.s6_addr32[0],
sin6->sin6_addr.s6_addr32[1],
sin6->sin6_addr.s6_addr32[2],
sin6->sin6_addr.s6_addr32[3],
dlm_config.ci_tcp_port, sk->sk_err,
sk->sk_err_soft);
}
out:
read_unlock_bh(&sk->sk_callback_lock);
if (orig_report)
orig_report(sk);
}
/* Note: sk_callback_lock must be locked before calling this function. */
static void save_listen_callbacks(struct socket *sock)
{
struct sock *sk = sock->sk;
listen_sock.sk_data_ready = sk->sk_data_ready;
listen_sock.sk_state_change = sk->sk_state_change;
listen_sock.sk_write_space = sk->sk_write_space;
listen_sock.sk_error_report = sk->sk_error_report;
}
static void restore_callbacks(struct socket *sock)
{
struct sock *sk = sock->sk;
write_lock_bh(&sk->sk_callback_lock);
sk->sk_user_data = NULL;
sk->sk_data_ready = listen_sock.sk_data_ready;
sk->sk_state_change = listen_sock.sk_state_change;
sk->sk_write_space = listen_sock.sk_write_space;
sk->sk_error_report = listen_sock.sk_error_report;
write_unlock_bh(&sk->sk_callback_lock);
}
/* Make a socket active */
static void add_sock(struct socket *sock, struct connection *con)
{
struct sock *sk = sock->sk;
write_lock_bh(&sk->sk_callback_lock);
con->sock = sock;
sk->sk_user_data = con;
/* Install a data_ready callback */
sk->sk_data_ready = lowcomms_data_ready;
sk->sk_write_space = lowcomms_write_space;
sk->sk_state_change = lowcomms_state_change;
sk->sk_allocation = GFP_NOFS;
sk->sk_error_report = lowcomms_error_report;
write_unlock_bh(&sk->sk_callback_lock);
}
/* Add the port number to an IPv6 or 4 sockaddr and return the address
length */
static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
int *addr_len)
{
saddr->ss_family = dlm_local_addr[0]->ss_family;
if (saddr->ss_family == AF_INET) {
struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
in4_addr->sin_port = cpu_to_be16(port);
*addr_len = sizeof(struct sockaddr_in);
memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
} else {
struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
in6_addr->sin6_port = cpu_to_be16(port);
*addr_len = sizeof(struct sockaddr_in6);
}
memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
}
/* Close a remote connection and tidy up */
static void close_connection(struct connection *con, bool and_other,
bool tx, bool rx)
{
bool closing = test_and_set_bit(CF_CLOSING, &con->flags);
if (tx && !closing && cancel_work_sync(&con->swork)) {
log_print("canceled swork for node %d", con->nodeid);
clear_bit(CF_WRITE_PENDING, &con->flags);
}
if (rx && !closing && cancel_work_sync(&con->rwork)) {
log_print("canceled rwork for node %d", con->nodeid);
clear_bit(CF_READ_PENDING, &con->flags);
}
mutex_lock(&con->sock_mutex);
if (con->sock) {
restore_callbacks(con->sock);
sock_release(con->sock);
con->sock = NULL;
}
if (con->othercon && and_other) {
/* Will only re-enter once. */
close_connection(con->othercon, false, true, true);
}
if (con->rx_page) {
__free_page(con->rx_page);
con->rx_page = NULL;
}
con->retries = 0;
mutex_unlock(&con->sock_mutex);
clear_bit(CF_CLOSING, &con->flags);
}
/* Data received from remote end */
static int receive_from_sock(struct connection *con)
{
int ret = 0;
struct msghdr msg = {};
struct kvec iov[2];
unsigned len;
int r;
int call_again_soon = 0;
int nvec;
mutex_lock(&con->sock_mutex);
if (con->sock == NULL) {
ret = -EAGAIN;
goto out_close;
}
if (con->nodeid == 0) {
ret = -EINVAL;
goto out_close;
}
if (con->rx_page == NULL) {
/*
* This doesn't need to be atomic, but I think it should
* improve performance if it is.
*/
con->rx_page = alloc_page(GFP_ATOMIC);
if (con->rx_page == NULL)
goto out_resched;
cbuf_init(&con->cb, PAGE_SIZE);
}
/*
* iov[0] is the bit of the circular buffer between the current end
* point (cb.base + cb.len) and the end of the buffer.
*/
iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
iov[1].iov_len = 0;
nvec = 1;
/*
* iov[1] is the bit of the circular buffer between the start of the
* buffer and the start of the currently used section (cb.base)
*/
if (cbuf_data(&con->cb) >= con->cb.base) {
iov[0].iov_len = PAGE_SIZE - cbuf_data(&con->cb);
iov[1].iov_len = con->cb.base;
iov[1].iov_base = page_address(con->rx_page);
nvec = 2;
}
len = iov[0].iov_len + iov[1].iov_len;
r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
MSG_DONTWAIT | MSG_NOSIGNAL);
if (ret <= 0)
goto out_close;
else if (ret == len)
call_again_soon = 1;
cbuf_add(&con->cb, ret);
ret = dlm_process_incoming_buffer(con->nodeid,
page_address(con->rx_page),
con->cb.base, con->cb.len,
PAGE_SIZE);
if (ret == -EBADMSG) {
log_print("lowcomms: addr=%p, base=%u, len=%u, read=%d",
page_address(con->rx_page), con->cb.base,
con->cb.len, r);
}
if (ret < 0)
goto out_close;
cbuf_eat(&con->cb, ret);
if (cbuf_empty(&con->cb) && !call_again_soon) {
__free_page(con->rx_page);
con->rx_page = NULL;
}
if (call_again_soon)
goto out_resched;
mutex_unlock(&con->sock_mutex);
return 0;
out_resched:
if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
queue_work(recv_workqueue, &con->rwork);
mutex_unlock(&con->sock_mutex);
return -EAGAIN;
out_close:
mutex_unlock(&con->sock_mutex);
if (ret != -EAGAIN) {
close_connection(con, true, true, false);
/* Reconnect when there is something to send */
}
/* Don't return success if we really got EOF */
if (ret == 0)
ret = -EAGAIN;
return ret;
}
/* Listening socket is busy, accept a connection */
static int tcp_accept_from_sock(struct connection *con)
{
int result;
struct sockaddr_storage peeraddr;
struct socket *newsock;
int len;
int nodeid;
struct connection *newcon;
struct connection *addcon;
mutex_lock(&connections_lock);
if (!dlm_allow_conn) {
mutex_unlock(&connections_lock);
return -1;
}
mutex_unlock(&connections_lock);
mutex_lock_nested(&con->sock_mutex, 0);
if (!con->sock) {
mutex_unlock(&con->sock_mutex);
return -ENOTCONN;
}
result = kernel_accept(con->sock, &newsock, O_NONBLOCK);
if (result < 0)
goto accept_err;
/* Get the connected socket's peer */
memset(&peeraddr, 0, sizeof(peeraddr));
if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
&len, 2)) {
result = -ECONNABORTED;
goto accept_err;
}
/* Get the new node's NODEID */
make_sockaddr(&peeraddr, 0, &len);
if (addr_to_nodeid(&peeraddr, &nodeid)) {
unsigned char *b=(unsigned char *)&peeraddr;
log_print("connect from non cluster node");
print_hex_dump_bytes("ss: ", DUMP_PREFIX_NONE,
b, sizeof(struct sockaddr_storage));
sock_release(newsock);
mutex_unlock(&con->sock_mutex);
return -1;
}
log_print("got connection from %d", nodeid);
/* Check to see if we already have a connection to this node. This
* could happen if the two nodes initiate a connection at roughly
* the same time and the connections cross on the wire.
* In this case we store the incoming one in "othercon"
*/
newcon = nodeid2con(nodeid, GFP_NOFS);
if (!newcon) {
result = -ENOMEM;
goto accept_err;
}
mutex_lock_nested(&newcon->sock_mutex, 1);
if (newcon->sock) {
struct connection *othercon = newcon->othercon;
if (!othercon) {
othercon = kmem_cache_zalloc(con_cache, GFP_NOFS);
if (!othercon) {
log_print("failed to allocate incoming socket");
mutex_unlock(&newcon->sock_mutex);
result = -ENOMEM;
goto accept_err;
}
othercon->nodeid = nodeid;
othercon->rx_action = receive_from_sock;
mutex_init(&othercon->sock_mutex);
INIT_LIST_HEAD(&othercon->writequeue);
spin_lock_init(&othercon->writequeue_lock);
INIT_WORK(&othercon->swork, process_send_sockets);
INIT_WORK(&othercon->rwork, process_recv_sockets);
set_bit(CF_IS_OTHERCON, &othercon->flags);
}
mutex_lock_nested(&othercon->sock_mutex, 2);
if (!othercon->sock) {
newcon->othercon = othercon;
add_sock(newsock, othercon);
addcon = othercon;
mutex_unlock(&othercon->sock_mutex);
}
else {
printk("Extra connection from node %d attempted\n", nodeid);
result = -EAGAIN;
mutex_unlock(&othercon->sock_mutex);
mutex_unlock(&newcon->sock_mutex);
goto accept_err;
}
}
else {
newcon->rx_action = receive_from_sock;
/* accept copies the sk after we've saved the callbacks, so we
don't want to save them a second time or comm errors will
result in calling sk_error_report recursively. */
add_sock(newsock, newcon);
addcon = newcon;
}
mutex_unlock(&newcon->sock_mutex);
/*
* Add it to the active queue in case we got data
* between processing the accept adding the socket
* to the read_sockets list
*/
if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
queue_work(recv_workqueue, &addcon->rwork);
mutex_unlock(&con->sock_mutex);
return 0;
accept_err:
mutex_unlock(&con->sock_mutex);
if (newsock)
sock_release(newsock);
if (result != -EAGAIN)
log_print("error accepting connection from node: %d", result);
return result;
}
static int sctp_accept_from_sock(struct connection *con)
{
/* Check that the new node is in the lockspace */
struct sctp_prim prim;
int nodeid;
int prim_len, ret;
int addr_len;
struct connection *newcon;
struct connection *addcon;
struct socket *newsock;
mutex_lock(&connections_lock);
if (!dlm_allow_conn) {
mutex_unlock(&connections_lock);
return -1;
}
mutex_unlock(&connections_lock);
mutex_lock_nested(&con->sock_mutex, 0);
ret = kernel_accept(con->sock, &newsock, O_NONBLOCK);
if (ret < 0)
goto accept_err;
memset(&prim, 0, sizeof(struct sctp_prim));
prim_len = sizeof(struct sctp_prim);
ret = kernel_getsockopt(newsock, IPPROTO_SCTP, SCTP_PRIMARY_ADDR,
(char *)&prim, &prim_len);
if (ret < 0) {
log_print("getsockopt/sctp_primary_addr failed: %d", ret);
goto accept_err;
}
make_sockaddr(&prim.ssp_addr, 0, &addr_len);
ret = addr_to_nodeid(&prim.ssp_addr, &nodeid);
if (ret) {
unsigned char *b = (unsigned char *)&prim.ssp_addr;
log_print("reject connect from unknown addr");
print_hex_dump_bytes("ss: ", DUMP_PREFIX_NONE,
b, sizeof(struct sockaddr_storage));
goto accept_err;
}
newcon = nodeid2con(nodeid, GFP_NOFS);
if (!newcon) {
ret = -ENOMEM;
goto accept_err;
}
mutex_lock_nested(&newcon->sock_mutex, 1);
if (newcon->sock) {
struct connection *othercon = newcon->othercon;
if (!othercon) {
othercon = kmem_cache_zalloc(con_cache, GFP_NOFS);
if (!othercon) {
log_print("failed to allocate incoming socket");
mutex_unlock(&newcon->sock_mutex);
ret = -ENOMEM;
goto accept_err;
}
othercon->nodeid = nodeid;
othercon->rx_action = receive_from_sock;
mutex_init(&othercon->sock_mutex);
INIT_LIST_HEAD(&othercon->writequeue);
spin_lock_init(&othercon->writequeue_lock);
INIT_WORK(&othercon->swork, process_send_sockets);
INIT_WORK(&othercon->rwork, process_recv_sockets);
set_bit(CF_IS_OTHERCON, &othercon->flags);
}
mutex_lock_nested(&othercon->sock_mutex, 2);
if (!othercon->sock) {
newcon->othercon = othercon;
add_sock(newsock, othercon);
addcon = othercon;
mutex_unlock(&othercon->sock_mutex);
} else {
printk("Extra connection from node %d attempted\n", nodeid);
ret = -EAGAIN;
mutex_unlock(&othercon->sock_mutex);
mutex_unlock(&newcon->sock_mutex);
goto accept_err;
}
} else {
newcon->rx_action = receive_from_sock;
add_sock(newsock, newcon);
addcon = newcon;
}
log_print("connected to %d", nodeid);
mutex_unlock(&newcon->sock_mutex);
/*
* Add it to the active queue in case we got data
* between processing the accept adding the socket
* to the read_sockets list
*/
if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
queue_work(recv_workqueue, &addcon->rwork);
mutex_unlock(&con->sock_mutex);
return 0;
accept_err:
mutex_unlock(&con->sock_mutex);
if (newsock)
sock_release(newsock);
if (ret != -EAGAIN)
log_print("error accepting connection from node: %d", ret);
return ret;
}
static void free_entry(struct writequeue_entry *e)
{
__free_page(e->page);
kfree(e);
}
/*
* writequeue_entry_complete - try to delete and free write queue entry
* @e: write queue entry to try to delete
* @completed: bytes completed
*
* writequeue_lock must be held.
*/
static void writequeue_entry_complete(struct writequeue_entry *e, int completed)
{
e->offset += completed;
e->len -= completed;
if (e->len == 0 && e->users == 0) {
list_del(&e->list);
free_entry(e);
}
}
/*
* sctp_bind_addrs - bind a SCTP socket to all our addresses
*/
static int sctp_bind_addrs(struct connection *con, uint16_t port)
{
struct sockaddr_storage localaddr;
int i, addr_len, result = 0;
for (i = 0; i < dlm_local_count; i++) {
memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
make_sockaddr(&localaddr, port, &addr_len);
if (!i)
result = kernel_bind(con->sock,
(struct sockaddr *)&localaddr,
addr_len);
else
result = kernel_setsockopt(con->sock, SOL_SCTP,
SCTP_SOCKOPT_BINDX_ADD,
(char *)&localaddr, addr_len);
if (result < 0) {
log_print("Can't bind to %d addr number %d, %d.\n",
port, i + 1, result);
break;
}
}
return result;
}
/* Initiate an SCTP association.
This is a special case of send_to_sock() in that we don't yet have a
peeled-off socket for this association, so we use the listening socket
and add the primary IP address of the remote node.
*/
static void sctp_connect_to_sock(struct connection *con)
{
struct sockaddr_storage daddr;
int one = 1;
int result;
int addr_len;
struct socket *sock;
if (con->nodeid == 0) {
log_print("attempt to connect sock 0 foiled");
return;
}
mutex_lock(&con->sock_mutex);
/* Some odd races can cause double-connects, ignore them */
if (con->retries++ > MAX_CONNECT_RETRIES)
goto out;
if (con->sock) {
log_print("node %d already connected.", con->nodeid);
goto out;
}
memset(&daddr, 0, sizeof(daddr));
result = nodeid_to_addr(con->nodeid, &daddr, NULL, true);
if (result < 0) {
log_print("no address for nodeid %d", con->nodeid);
goto out;
}
/* Create a socket to communicate with */
result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
SOCK_STREAM, IPPROTO_SCTP, &sock);
if (result < 0)
goto socket_err;
con->rx_action = receive_from_sock;
con->connect_action = sctp_connect_to_sock;
add_sock(sock, con);
/* Bind to all addresses. */
if (sctp_bind_addrs(con, 0))
goto bind_err;
make_sockaddr(&daddr, dlm_config.ci_tcp_port, &addr_len);
log_print("connecting to %d", con->nodeid);
/* Turn off Nagle's algorithm */
kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
sizeof(one));
result = sock->ops->connect(sock, (struct sockaddr *)&daddr, addr_len,
O_NONBLOCK);
if (result == -EINPROGRESS)
result = 0;
if (result == 0)
goto out;
bind_err:
con->sock = NULL;
sock_release(sock);
socket_err:
/*
* Some errors are fatal and this list might need adjusting. For other
* errors we try again until the max number of retries is reached.
*/
if (result != -EHOSTUNREACH &&
result != -ENETUNREACH &&
result != -ENETDOWN &&
result != -EINVAL &&
result != -EPROTONOSUPPORT) {
log_print("connect %d try %d error %d", con->nodeid,
con->retries, result);
mutex_unlock(&con->sock_mutex);
msleep(1000);
lowcomms_connect_sock(con);
return;
}
out:
mutex_unlock(&con->sock_mutex);
}
/* Connect a new socket to its peer */
static void tcp_connect_to_sock(struct connection *con)
{
struct sockaddr_storage saddr, src_addr;
int addr_len;
struct socket *sock = NULL;
int one = 1;
int result;
if (con->nodeid == 0) {
log_print("attempt to connect sock 0 foiled");
return;
}
mutex_lock(&con->sock_mutex);
if (con->retries++ > MAX_CONNECT_RETRIES)
goto out;
/* Some odd races can cause double-connects, ignore them */
if (con->sock)
goto out;
/* Create a socket to communicate with */
result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
SOCK_STREAM, IPPROTO_TCP, &sock);
if (result < 0)
goto out_err;
memset(&saddr, 0, sizeof(saddr));
result = nodeid_to_addr(con->nodeid, &saddr, NULL, false);
if (result < 0) {
log_print("no address for nodeid %d", con->nodeid);
goto out_err;
}
con->rx_action = receive_from_sock;
con->connect_action = tcp_connect_to_sock;
add_sock(sock, con);
/* Bind to our cluster-known address connecting to avoid
routing problems */
memcpy(&src_addr, dlm_local_addr[0], sizeof(src_addr));
make_sockaddr(&src_addr, 0, &addr_len);
result = sock->ops->bind(sock, (struct sockaddr *) &src_addr,
addr_len);
if (result < 0) {
log_print("could not bind for connect: %d", result);
/* This *may* not indicate a critical error */
}
make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
log_print("connecting to %d", con->nodeid);
/* Turn off Nagle's algorithm */
kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
sizeof(one));
result = sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
O_NONBLOCK);
if (result == -EINPROGRESS)
result = 0;
if (result == 0)
goto out;
out_err:
if (con->sock) {
sock_release(con->sock);
con->sock = NULL;
} else if (sock) {
sock_release(sock);
}
/*
* Some errors are fatal and this list might need adjusting. For other
* errors we try again until the max number of retries is reached.
*/
if (result != -EHOSTUNREACH &&
result != -ENETUNREACH &&
result != -ENETDOWN &&
result != -EINVAL &&
result != -EPROTONOSUPPORT) {
log_print("connect %d try %d error %d", con->nodeid,
con->retries, result);
mutex_unlock(&con->sock_mutex);
msleep(1000);
lowcomms_connect_sock(con);
return;
}
out:
mutex_unlock(&con->sock_mutex);
return;
}
static struct socket *tcp_create_listen_sock(struct connection *con,
struct sockaddr_storage *saddr)
{
struct socket *sock = NULL;
int result = 0;
int one = 1;
int addr_len;
if (dlm_local_addr[0]->ss_family == AF_INET)
addr_len = sizeof(struct sockaddr_in);
else
addr_len = sizeof(struct sockaddr_in6);
/* Create a socket to communicate with */
result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
SOCK_STREAM, IPPROTO_TCP, &sock);
if (result < 0) {
log_print("Can't create listening comms socket");
goto create_out;
}
/* Turn off Nagle's algorithm */
kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
sizeof(one));
result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
(char *)&one, sizeof(one));
if (result < 0) {
log_print("Failed to set SO_REUSEADDR on socket: %d", result);
}
write_lock_bh(&sock->sk->sk_callback_lock);
sock->sk->sk_user_data = con;
save_listen_callbacks(sock);
con->rx_action = tcp_accept_from_sock;
con->connect_action = tcp_connect_to_sock;
write_unlock_bh(&sock->sk->sk_callback_lock);
/* Bind to our port */
make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
if (result < 0) {
log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
sock_release(sock);
sock = NULL;
con->sock = NULL;
goto create_out;
}
result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
(char *)&one, sizeof(one));
if (result < 0) {
log_print("Set keepalive failed: %d", result);
}
result = sock->ops->listen(sock, 5);
if (result < 0) {
log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
sock_release(sock);
sock = NULL;
goto create_out;
}
create_out:
return sock;
}
/* Get local addresses */
static void init_local(void)
{
struct sockaddr_storage sas, *addr;
int i;
dlm_local_count = 0;
for (i = 0; i < DLM_MAX_ADDR_COUNT; i++) {
if (dlm_our_addr(&sas, i))
break;
addr = kmemdup(&sas, sizeof(*addr), GFP_NOFS);
if (!addr)
break;
dlm_local_addr[dlm_local_count++] = addr;
}
}
/* Initialise SCTP socket and bind to all interfaces */
static int sctp_listen_for_all(void)
{
struct socket *sock = NULL;
int result = -EINVAL;
struct connection *con = nodeid2con(0, GFP_NOFS);
int bufsize = NEEDED_RMEM;
int one = 1;
if (!con)
return -ENOMEM;
log_print("Using SCTP for communications");
result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
SOCK_STREAM, IPPROTO_SCTP, &sock);
if (result < 0) {
log_print("Can't create comms socket, check SCTP is loaded");
goto out;
}
result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUFFORCE,
(char *)&bufsize, sizeof(bufsize));
if (result)
log_print("Error increasing buffer space on socket %d", result);
result = kernel_setsockopt(sock, SOL_SCTP, SCTP_NODELAY, (char *)&one,
sizeof(one));
if (result < 0)
log_print("Could not set SCTP NODELAY error %d\n", result);
write_lock_bh(&sock->sk->sk_callback_lock);
/* Init con struct */
sock->sk->sk_user_data = con;
save_listen_callbacks(sock);
con->sock = sock;
con->sock->sk->sk_data_ready = lowcomms_data_ready;
con->rx_action = sctp_accept_from_sock;
con->connect_action = sctp_connect_to_sock;
write_unlock_bh(&sock->sk->sk_callback_lock);
/* Bind to all addresses. */
if (sctp_bind_addrs(con, dlm_config.ci_tcp_port))
goto create_delsock;
result = sock->ops->listen(sock, 5);
if (result < 0) {
log_print("Can't set socket listening");
goto create_delsock;
}
return 0;
create_delsock:
sock_release(sock);
con->sock = NULL;
out:
return result;
}
static int tcp_listen_for_all(void)
{
struct socket *sock = NULL;
struct connection *con = nodeid2con(0, GFP_NOFS);
int result = -EINVAL;
if (!con)
return -ENOMEM;
/* We don't support multi-homed hosts */
if (dlm_local_addr[1] != NULL) {
log_print("TCP protocol can't handle multi-homed hosts, "
"try SCTP");
return -EINVAL;
}
log_print("Using TCP for communications");
sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
if (sock) {
add_sock(sock, con);
result = 0;
}
else {
result = -EADDRINUSE;
}
return result;
}
static struct writequeue_entry *new_writequeue_entry(struct connection *con,
gfp_t allocation)
{
struct writequeue_entry *entry;
entry = kmalloc(sizeof(struct writequeue_entry), allocation);
if (!entry)
return NULL;
entry->page = alloc_page(allocation);
if (!entry->page) {
kfree(entry);
return NULL;
}
entry->offset = 0;
entry->len = 0;
entry->end = 0;
entry->users = 0;
entry->con = con;
return entry;
}
void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
{
struct connection *con;
struct writequeue_entry *e;
int offset = 0;
con = nodeid2con(nodeid, allocation);
if (!con)
return NULL;
spin_lock(&con->writequeue_lock);
e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
if ((&e->list == &con->writequeue) ||
(PAGE_SIZE - e->end < len)) {
e = NULL;
} else {
offset = e->end;
e->end += len;
e->users++;
}
spin_unlock(&con->writequeue_lock);
if (e) {
got_one:
*ppc = page_address(e->page) + offset;
return e;
}
e = new_writequeue_entry(con, allocation);
if (e) {
spin_lock(&con->writequeue_lock);
offset = e->end;
e->end += len;
e->users++;
list_add_tail(&e->list, &con->writequeue);
spin_unlock(&con->writequeue_lock);
goto got_one;
}
return NULL;
}
void dlm_lowcomms_commit_buffer(void *mh)
{
struct writequeue_entry *e = (struct writequeue_entry *)mh;
struct connection *con = e->con;
int users;
spin_lock(&con->writequeue_lock);
users = --e->users;
if (users)
goto out;
e->len = e->end - e->offset;
spin_unlock(&con->writequeue_lock);
queue_work(send_workqueue, &con->swork);
return;
out:
spin_unlock(&con->writequeue_lock);
return;
}
/* Send a message */
static void send_to_sock(struct connection *con)
{
int ret = 0;
const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
struct writequeue_entry *e;
int len, offset;
int count = 0;
mutex_lock(&con->sock_mutex);
if (con->sock == NULL)
goto out_connect;
spin_lock(&con->writequeue_lock);
for (;;) {
e = list_entry(con->writequeue.next, struct writequeue_entry,
list);
if ((struct list_head *) e == &con->writequeue)
break;
len = e->len;
offset = e->offset;
BUG_ON(len == 0 && e->users == 0);
spin_unlock(&con->writequeue_lock);
ret = 0;
if (len) {
ret = kernel_sendpage(con->sock, e->page, offset, len,
msg_flags);
if (ret == -EAGAIN || ret == 0) {
if (ret == -EAGAIN &&
test_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags) &&
!test_and_set_bit(CF_APP_LIMITED, &con->flags)) {
/* Notify TCP that we're limited by the
* application window size.
*/
set_bit(SOCK_NOSPACE, &con->sock->flags);
con->sock->sk->sk_write_pending++;
}
cond_resched();
goto out;
} else if (ret < 0)
goto send_error;
}
/* Don't starve people filling buffers */
if (++count >= MAX_SEND_MSG_COUNT) {
cond_resched();
count = 0;
}
spin_lock(&con->writequeue_lock);
writequeue_entry_complete(e, ret);
}
spin_unlock(&con->writequeue_lock);
out:
mutex_unlock(&con->sock_mutex);
return;
send_error:
mutex_unlock(&con->sock_mutex);
close_connection(con, true, false, true);
/* Requeue the send work. When the work daemon runs again, it will try
a new connection, then call this function again. */
queue_work(send_workqueue, &con->swork);
return;
out_connect:
mutex_unlock(&con->sock_mutex);
queue_work(send_workqueue, &con->swork);
cond_resched();
}
static void clean_one_writequeue(struct connection *con)
{
struct writequeue_entry *e, *safe;
spin_lock(&con->writequeue_lock);
list_for_each_entry_safe(e, safe, &con->writequeue, list) {
list_del(&e->list);
free_entry(e);
}
spin_unlock(&con->writequeue_lock);
}
/* Called from recovery when it knows that a node has
left the cluster */
int dlm_lowcomms_close(int nodeid)
{
struct connection *con;
struct dlm_node_addr *na;
log_print("closing connection to node %d", nodeid);
con = nodeid2con(nodeid, 0);
if (con) {
set_bit(CF_CLOSE, &con->flags);
close_connection(con, true, true, true);
clean_one_writequeue(con);
}
spin_lock(&dlm_node_addrs_spin);
na = find_node_addr(nodeid);
if (na) {
list_del(&na->list);
while (na->addr_count--)
kfree(na->addr[na->addr_count]);
kfree(na);
}
spin_unlock(&dlm_node_addrs_spin);
return 0;
}
/* Receive workqueue function */
static void process_recv_sockets(struct work_struct *work)
{
struct connection *con = container_of(work, struct connection, rwork);
int err;
clear_bit(CF_READ_PENDING, &con->flags);
do {
err = con->rx_action(con);
} while (!err);
}
/* Send workqueue function */
static void process_send_sockets(struct work_struct *work)
{
struct connection *con = container_of(work, struct connection, swork);
clear_bit(CF_WRITE_PENDING, &con->flags);
if (con->sock == NULL) /* not mutex protected so check it inside too */
con->connect_action(con);
if (!list_empty(&con->writequeue))
send_to_sock(con);
}
/* Discard all entries on the write queues */
static void clean_writequeues(void)
{
foreach_conn(clean_one_writequeue);
}
static void work_stop(void)
{
destroy_workqueue(recv_workqueue);
destroy_workqueue(send_workqueue);
}
static int work_start(void)
{
recv_workqueue = alloc_workqueue("dlm_recv",
WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
if (!recv_workqueue) {
log_print("can't start dlm_recv");
return -ENOMEM;
}
send_workqueue = alloc_workqueue("dlm_send",
WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
if (!send_workqueue) {
log_print("can't start dlm_send");
destroy_workqueue(recv_workqueue);
return -ENOMEM;
}
return 0;
}
static void _stop_conn(struct connection *con, bool and_other)
{
mutex_lock(&con->sock_mutex);
set_bit(CF_CLOSE, &con->flags);
set_bit(CF_READ_PENDING, &con->flags);
set_bit(CF_WRITE_PENDING, &con->flags);
if (con->sock && con->sock->sk) {
write_lock_bh(&con->sock->sk->sk_callback_lock);
con->sock->sk->sk_user_data = NULL;
write_unlock_bh(&con->sock->sk->sk_callback_lock);
}
if (con->othercon && and_other)
_stop_conn(con->othercon, false);
mutex_unlock(&con->sock_mutex);
}
static void stop_conn(struct connection *con)
{
_stop_conn(con, true);
}
static void free_conn(struct connection *con)
{
close_connection(con, true, true, true);
if (con->othercon)
kmem_cache_free(con_cache, con->othercon);
hlist_del(&con->list);
kmem_cache_free(con_cache, con);
}
static void work_flush(void)
{
int ok;
int i;
struct hlist_node *n;
struct connection *con;
flush_workqueue(recv_workqueue);
flush_workqueue(send_workqueue);
do {
ok = 1;
foreach_conn(stop_conn);
flush_workqueue(recv_workqueue);
flush_workqueue(send_workqueue);
for (i = 0; i < CONN_HASH_SIZE && ok; i++) {
hlist_for_each_entry_safe(con, n,
&connection_hash[i], list) {
ok &= test_bit(CF_READ_PENDING, &con->flags);
ok &= test_bit(CF_WRITE_PENDING, &con->flags);
if (con->othercon) {
ok &= test_bit(CF_READ_PENDING,
&con->othercon->flags);
ok &= test_bit(CF_WRITE_PENDING,
&con->othercon->flags);
}
}
}
} while (!ok);
}
void dlm_lowcomms_stop(void)
{
/* Set all the flags to prevent any
socket activity.
*/
mutex_lock(&connections_lock);
dlm_allow_conn = 0;
mutex_unlock(&connections_lock);
work_flush();
clean_writequeues();
foreach_conn(free_conn);
work_stop();
kmem_cache_destroy(con_cache);
}
int dlm_lowcomms_start(void)
{
int error = -EINVAL;
struct connection *con;
int i;
for (i = 0; i < CONN_HASH_SIZE; i++)
INIT_HLIST_HEAD(&connection_hash[i]);
init_local();
if (!dlm_local_count) {
error = -ENOTCONN;
log_print("no local IP address has been set");
goto fail;
}
error = -ENOMEM;
con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
__alignof__(struct connection), 0,
NULL);
if (!con_cache)
goto fail;
error = work_start();
if (error)
goto fail_destroy;
dlm_allow_conn = 1;
/* Start listening */
if (dlm_config.ci_protocol == 0)
error = tcp_listen_for_all();
else
error = sctp_listen_for_all();
if (error)
goto fail_unlisten;
return 0;
fail_unlisten:
dlm_allow_conn = 0;
con = nodeid2con(0,0);
if (con) {
close_connection(con, false, true, true);
kmem_cache_free(con_cache, con);
}
fail_destroy:
kmem_cache_destroy(con_cache);
fail:
return error;
}
void dlm_lowcomms_exit(void)
{
struct dlm_node_addr *na, *safe;
spin_lock(&dlm_node_addrs_spin);
list_for_each_entry_safe(na, safe, &dlm_node_addrs, list) {
list_del(&na->list);
while (na->addr_count--)
kfree(na->addr[na->addr_count]);
kfree(na);
}
spin_unlock(&dlm_node_addrs_spin);
}
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