/******************************************************************************
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
** Copyright (C) 2004-2006 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 it's
* 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.
*
* I don't see any problem with the recv thread executing the locking
* code on behalf of remote processes as the locking code is
* short, efficient and never waits.
*
*/
#include <asm/ioctls.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <linux/pagemap.h>
#include "dlm_internal.h"
#include "lowcomms.h"
#include "midcomms.h"
#include "config.h"
struct cbuf {
unsigned int base;
unsigned int len;
unsigned int mask;
};
#define NODE_INCREMENT 32
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;
}
/* Maximum number of incoming messages to process before
doing a cond_resched()
*/
#define MAX_RX_MSG_COUNT 25
struct connection {
struct socket *sock; /* NULL if not connected */
uint32_t nodeid; /* So we know who we are in the list */
struct rw_semaphore sock_sem; /* Stop connect races */
struct list_head read_list; /* On this list when ready for reading */
struct list_head write_list; /* On this list when ready for writing */
struct list_head state_list; /* On this list when ready to connect */
unsigned long flags; /* bit 1,2 = We are on the read/write lists */
#define CF_READ_PENDING 1
#define CF_WRITE_PENDING 2
#define CF_CONNECT_PENDING 3
#define CF_IS_OTHERCON 4
struct list_head writequeue; /* List of outgoing writequeue_entries */
struct list_head listenlist; /* List of allocated listening sockets */
spinlock_t writequeue_lock;
int (*rx_action) (struct connection *); /* What to do when active */
struct page *rx_page;
struct cbuf cb;
int retries;
atomic_t waiting_requests;
#define MAX_CONNECT_RETRIES 3
struct connection *othercon;
};
#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;
};
static struct sockaddr_storage dlm_local_addr;
/* Manage daemons */
static struct task_struct *recv_task;
static struct task_struct *send_task;
static wait_queue_t lowcomms_send_waitq_head;
static DECLARE_WAIT_QUEUE_HEAD(lowcomms_send_waitq);
static wait_queue_t lowcomms_recv_waitq_head;
static DECLARE_WAIT_QUEUE_HEAD(lowcomms_recv_waitq);
/* An array of pointers to connections, indexed by NODEID */
static struct connection **connections;
static DECLARE_MUTEX(connections_lock);
static struct kmem_cache *con_cache;
static int conn_array_size;
/* List of sockets that have reads pending */
static LIST_HEAD(read_sockets);
static DEFINE_SPINLOCK(read_sockets_lock);
/* List of sockets which have writes pending */
static LIST_HEAD(write_sockets);
static DEFINE_SPINLOCK(write_sockets_lock);
/* List of sockets which have connects pending */
static LIST_HEAD(state_sockets);
static DEFINE_SPINLOCK(state_sockets_lock);
static struct connection *nodeid2con(int nodeid, gfp_t allocation)
{
struct connection *con = NULL;
down(&connections_lock);
if (nodeid >= conn_array_size) {
int new_size = nodeid + NODE_INCREMENT;
struct connection **new_conns;
new_conns = kzalloc(sizeof(struct connection *) *
new_size, allocation);
if (!new_conns)
goto finish;
memcpy(new_conns, connections, sizeof(struct connection *) * conn_array_size);
conn_array_size = new_size;
kfree(connections);
connections = new_conns;
}
con = connections[nodeid];
if (con == NULL && allocation) {
con = kmem_cache_zalloc(con_cache, allocation);
if (!con)
goto finish;
con->nodeid = nodeid;
init_rwsem(&con->sock_sem);
INIT_LIST_HEAD(&con->writequeue);
spin_lock_init(&con->writequeue_lock);
connections[nodeid] = con;
}
finish:
up(&connections_lock);
return con;
}
/* Data available on socket or listen socket received a connect */
static void lowcomms_data_ready(struct sock *sk, int count_unused)
{
struct connection *con = sock2con(sk);
atomic_inc(&con->waiting_requests);
if (test_and_set_bit(CF_READ_PENDING, &con->flags))
return;
spin_lock_bh(&read_sockets_lock);
list_add_tail(&con->read_list, &read_sockets);
spin_unlock_bh(&read_sockets_lock);
wake_up_interruptible(&lowcomms_recv_waitq);
}
static void lowcomms_write_space(struct sock *sk)
{
struct connection *con = sock2con(sk);
if (test_and_set_bit(CF_WRITE_PENDING, &con->flags))
return;
spin_lock_bh(&write_sockets_lock);
list_add_tail(&con->write_list, &write_sockets);
spin_unlock_bh(&write_sockets_lock);
wake_up_interruptible(&lowcomms_send_waitq);
}
static inline void lowcomms_connect_sock(struct connection *con)
{
if (test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
return;
spin_lock_bh(&state_sockets_lock);
list_add_tail(&con->state_list, &state_sockets);
spin_unlock_bh(&state_sockets_lock);
wake_up_interruptible(&lowcomms_send_waitq);
}
static void lowcomms_state_change(struct sock *sk)
{
if (sk->sk_state == TCP_ESTABLISHED)
lowcomms_write_space(sk);
}
/* Make a socket active */
static int add_sock(struct socket *sock, struct connection *con)
{
con->sock = sock;
/* Install a data_ready callback */
con->sock->sk->sk_data_ready = lowcomms_data_ready;
con->sock->sk->sk_write_space = lowcomms_write_space;
con->sock->sk->sk_state_change = lowcomms_state_change;
return 0;
}
/* Add the port number to an IP6 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.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);
} else {
struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
in6_addr->sin6_port = cpu_to_be16(port);
*addr_len = sizeof(struct sockaddr_in6);
}
}
/* Close a remote connection and tidy up */
static void close_connection(struct connection *con, bool and_other)
{
down_write(&con->sock_sem);
if (con->sock) {
sock_release(con->sock);
con->sock = NULL;
}
if (con->othercon && and_other) {
/* Will only re-enter once. */
close_connection(con->othercon, false);
}
if (con->rx_page) {
__free_page(con->rx_page);
con->rx_page = NULL;
}
con->retries = 0;
up_write(&con->sock_sem);
}
/* Data received from remote end */
static int receive_from_sock(struct connection *con)
{
int ret = 0;
struct msghdr msg;
struct iovec iov[2];
mm_segment_t fs;
unsigned len;
int r;
int call_again_soon = 0;
down_read(&con->sock_sem);
if (con->sock == NULL)
goto out;
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_CACHE_SIZE);
}
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_iovlen = 1;
msg.msg_iov = iov;
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_flags = 0;
/*
* 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;
/*
* 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_CACHE_SIZE - cbuf_data(&con->cb);
iov[1].iov_len = con->cb.base;
iov[1].iov_base = page_address(con->rx_page);
msg.msg_iovlen = 2;
}
len = iov[0].iov_len + iov[1].iov_len;
fs = get_fs();
set_fs(get_ds());
r = ret = sock_recvmsg(con->sock, &msg, len,
MSG_DONTWAIT | MSG_NOSIGNAL);
set_fs(fs);
if (ret <= 0)
goto out_close;
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_CACHE_SIZE);
if (ret == -EBADMSG) {
printk(KERN_INFO "dlm: lowcomms: addr=%p, base=%u, len=%u, "
"iov_len=%u, iov_base[0]=%p, read=%d\n",
page_address(con->rx_page), con->cb.base, con->cb.len,
len, iov[0].iov_base, 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;
}
out:
if (call_again_soon)
goto out_resched;
up_read(&con->sock_sem);
return 0;
out_resched:
lowcomms_data_ready(con->sock->sk, 0);
up_read(&con->sock_sem);
cond_resched();
return 0;
out_close:
up_read(&con->sock_sem);
if (ret != -EAGAIN && !test_bit(CF_IS_OTHERCON, &con->flags)) {
close_connection(con, false);
/* Reconnect when there is something to send */
}
return ret;
}
/* Listening socket is busy, accept a connection */
static int accept_from_sock(struct connection *con)
{
int result;
struct sockaddr_storage peeraddr;
struct socket *newsock;
int len;
int nodeid;
struct connection *newcon;
memset(&peeraddr, 0, sizeof(peeraddr));
result = sock_create_kern(dlm_local_addr.ss_family, SOCK_STREAM,
IPPROTO_TCP, &newsock);
if (result < 0)
return -ENOMEM;
down_read(&con->sock_sem);
result = -ENOTCONN;
if (con->sock == NULL)
goto accept_err;
newsock->type = con->sock->type;
newsock->ops = con->sock->ops;
result = con->sock->ops->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 (dlm_addr_to_nodeid(&peeraddr, &nodeid)) {
printk("dlm: connect from non cluster node\n");
sock_release(newsock);
up_read(&con->sock_sem);
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.
* TEMPORARY FIX:
* In this case we store the incoming one in "othercon"
*/
newcon = nodeid2con(nodeid, GFP_KERNEL);
if (!newcon) {
result = -ENOMEM;
goto accept_err;
}
down_write(&newcon->sock_sem);
if (newcon->sock) {
struct connection *othercon = newcon->othercon;
if (!othercon) {
othercon = kmem_cache_zalloc(con_cache, GFP_KERNEL);
if (!othercon) {
printk("dlm: failed to allocate incoming socket\n");
up_write(&newcon->sock_sem);
result = -ENOMEM;
goto accept_err;
}
othercon->nodeid = nodeid;
othercon->rx_action = receive_from_sock;
init_rwsem(&othercon->sock_sem);
set_bit(CF_IS_OTHERCON, &othercon->flags);
newcon->othercon = othercon;
}
othercon->sock = newsock;
newsock->sk->sk_user_data = othercon;
add_sock(newsock, othercon);
}
else {
newsock->sk->sk_user_data = newcon;
newcon->rx_action = receive_from_sock;
add_sock(newsock, newcon);
}
up_write(&newcon->sock_sem);
/*
* Add it to the active queue in case we got data
* beween processing the accept adding the socket
* to the read_sockets list
*/
lowcomms_data_ready(newsock->sk, 0);
up_read(&con->sock_sem);
return 0;
accept_err:
up_read(&con->sock_sem);
sock_release(newsock);
if (result != -EAGAIN)
printk("dlm: error accepting connection from node: %d\n", result);
return result;
}
/* Connect a new socket to its peer */
static void connect_to_sock(struct connection *con)
{
int result = -EHOSTUNREACH;
struct sockaddr_storage saddr;
int addr_len;
struct socket *sock;
if (con->nodeid == 0) {
log_print("attempt to connect sock 0 foiled");
return;
}
down_write(&con->sock_sem);
if (con->retries++ > MAX_CONNECT_RETRIES)
goto out;
/* Some odd races can cause double-connects, ignore them */
if (con->sock) {
result = 0;
goto out;
}
/* Create a socket to communicate with */
result = sock_create_kern(dlm_local_addr.ss_family, SOCK_STREAM,
IPPROTO_TCP, &sock);
if (result < 0)
goto out_err;
memset(&saddr, 0, sizeof(saddr));
if (dlm_nodeid_to_addr(con->nodeid, &saddr))
goto out_err;
sock->sk->sk_user_data = con;
con->rx_action = receive_from_sock;
make_sockaddr(&saddr, dlm_config.tcp_port, &addr_len);
add_sock(sock, con);
log_print("connecting to %d", con->nodeid);
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;
}
/*
* 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) {
lowcomms_connect_sock(con);
result = 0;
}
out:
up_write(&con->sock_sem);
return;
}
static struct socket *create_listen_sock(struct connection *con,
struct sockaddr_storage *saddr)
{
struct socket *sock = NULL;
mm_segment_t fs;
int result = 0;
int one = 1;
int addr_len;
if (dlm_local_addr.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(dlm_local_addr.ss_family, SOCK_STREAM, IPPROTO_TCP, &sock);
if (result < 0) {
printk("dlm: Can't create listening comms socket\n");
goto create_out;
}
fs = get_fs();
set_fs(get_ds());
result = sock_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
(char *)&one, sizeof(one));
set_fs(fs);
if (result < 0) {
printk("dlm: Failed to set SO_REUSEADDR on socket: result=%d\n",
result);
}
sock->sk->sk_user_data = con;
con->rx_action = accept_from_sock;
con->sock = sock;
/* Bind to our port */
make_sockaddr(saddr, dlm_config.tcp_port, &addr_len);
result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
if (result < 0) {
printk("dlm: Can't bind to port %d\n", dlm_config.tcp_port);
sock_release(sock);
sock = NULL;
con->sock = NULL;
goto create_out;
}
fs = get_fs();
set_fs(get_ds());
result = sock_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
(char *)&one, sizeof(one));
set_fs(fs);
if (result < 0) {
printk("dlm: Set keepalive failed: %d\n", result);
}
result = sock->ops->listen(sock, 5);
if (result < 0) {
printk("dlm: Can't listen on port %d\n", dlm_config.tcp_port);
sock_release(sock);
sock = NULL;
goto create_out;
}
create_out:
return sock;
}
/* Listen on all interfaces */
static int listen_for_all(void)
{
struct socket *sock = NULL;
struct connection *con = nodeid2con(0, GFP_KERNEL);
int result = -EINVAL;
/* We don't support multi-homed hosts */
set_bit(CF_IS_OTHERCON, &con->flags);
sock = create_listen_sock(con, &dlm_local_addr);
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;
int users = 0;
con = nodeid2con(nodeid, allocation);
if (!con)
return NULL;
e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
if ((&e->list == &con->writequeue) ||
(PAGE_CACHE_SIZE - e->end < len)) {
e = NULL;
} else {
offset = e->end;
e->end += len;
users = e->users++;
}
spin_unlock(&con->writequeue_lock);
if (e) {
got_one:
if (users == 0)
kmap(e->page);
*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;
users = 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;
users = --e->users;
if (users)
goto out;
e->len = e->end - e->offset;
kunmap(e->page);
spin_unlock(&con->writequeue_lock);
if (test_and_set_bit(CF_WRITE_PENDING, &con->flags) == 0) {
spin_lock_bh(&write_sockets_lock);
list_add_tail(&con->write_list, &write_sockets);
spin_unlock_bh(&write_sockets_lock);
wake_up_interruptible(&lowcomms_send_waitq);
}
return;
out:
spin_unlock(&con->writequeue_lock);
return;
}
static void free_entry(struct writequeue_entry *e)
{
__free_page(e->page);
kfree(e);
}
/* Send a message */
static void send_to_sock(struct connection *con)
{
int ret = 0;
ssize_t(*sendpage) (struct socket *, struct page *, int, size_t, int);
const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
struct writequeue_entry *e;
int len, offset;
down_read(&con->sock_sem);
if (con->sock == NULL)
goto out_connect;
sendpage = con->sock->ops->sendpage;
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 = sendpage(con->sock, e->page, offset, len,
msg_flags);
if (ret == -EAGAIN || ret == 0)
goto out;
if (ret <= 0)
goto send_error;
}
else {
/* Don't starve people filling buffers */
cond_resched();
}
spin_lock(&con->writequeue_lock);
e->offset += ret;
e->len -= ret;
if (e->len == 0 && e->users == 0) {
list_del(&e->list);
kunmap(e->page);
free_entry(e);
continue;
}
}
spin_unlock(&con->writequeue_lock);
out:
up_read(&con->sock_sem);
return;
send_error:
up_read(&con->sock_sem);
close_connection(con, false);
lowcomms_connect_sock(con);
return;
out_connect:
up_read(&con->sock_sem);
lowcomms_connect_sock(con);
return;
}
static void clean_one_writequeue(struct connection *con)
{
struct list_head *list;
struct list_head *temp;
spin_lock(&con->writequeue_lock);
list_for_each_safe(list, temp, &con->writequeue) {
struct writequeue_entry *e =
list_entry(list, struct writequeue_entry, 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;
if (!connections)
goto out;
log_print("closing connection to node %d", nodeid);
con = nodeid2con(nodeid, 0);
if (con) {
clean_one_writequeue(con);
close_connection(con, true);
atomic_set(&con->waiting_requests, 0);
}
return 0;
out:
return -1;
}
/* API send message call, may queue the request */
/* N.B. This is the old interface - use the new one for new calls */
int lowcomms_send_message(int nodeid, char *buf, int len, gfp_t allocation)
{
struct writequeue_entry *e;
char *b;
e = dlm_lowcomms_get_buffer(nodeid, len, allocation, &b);
if (e) {
memcpy(b, buf, len);
dlm_lowcomms_commit_buffer(e);
return 0;
}
return -ENOBUFS;
}
/* Look for activity on active sockets */
static void process_sockets(void)
{
struct list_head *list;
struct list_head *temp;
int count = 0;
spin_lock_bh(&read_sockets_lock);
list_for_each_safe(list, temp, &read_sockets) {
struct connection *con =
list_entry(list, struct connection, read_list);
list_del(&con->read_list);
clear_bit(CF_READ_PENDING, &con->flags);
spin_unlock_bh(&read_sockets_lock);
/* This can reach zero if we are processing requests
* as they come in.
*/
if (atomic_read(&con->waiting_requests) == 0) {
spin_lock_bh(&read_sockets_lock);
continue;
}
do {
con->rx_action(con);
/* Don't starve out everyone else */
if (++count >= MAX_RX_MSG_COUNT) {
cond_resched();
count = 0;
}
} while (!atomic_dec_and_test(&con->waiting_requests) &&
!kthread_should_stop());
spin_lock_bh(&read_sockets_lock);
}
spin_unlock_bh(&read_sockets_lock);
}
/* Try to send any messages that are pending
*/
static void process_output_queue(void)
{
struct list_head *list;
struct list_head *temp;
spin_lock_bh(&write_sockets_lock);
list_for_each_safe(list, temp, &write_sockets) {
struct connection *con =
list_entry(list, struct connection, write_list);
clear_bit(CF_WRITE_PENDING, &con->flags);
list_del(&con->write_list);
spin_unlock_bh(&write_sockets_lock);
send_to_sock(con);
spin_lock_bh(&write_sockets_lock);
}
spin_unlock_bh(&write_sockets_lock);
}
static void process_state_queue(void)
{
struct list_head *list;
struct list_head *temp;
spin_lock_bh(&state_sockets_lock);
list_for_each_safe(list, temp, &state_sockets) {
struct connection *con =
list_entry(list, struct connection, state_list);
list_del(&con->state_list);
clear_bit(CF_CONNECT_PENDING, &con->flags);
spin_unlock_bh(&state_sockets_lock);
connect_to_sock(con);
spin_lock_bh(&state_sockets_lock);
}
spin_unlock_bh(&state_sockets_lock);
}
/* Discard all entries on the write queues */
static void clean_writequeues(void)
{
int nodeid;
for (nodeid = 1; nodeid < conn_array_size; nodeid++) {
struct connection *con = nodeid2con(nodeid, 0);
if (con)
clean_one_writequeue(con);
}
}
static int read_list_empty(void)
{
int status;
spin_lock_bh(&read_sockets_lock);
status = list_empty(&read_sockets);
spin_unlock_bh(&read_sockets_lock);
return status;
}
/* DLM Transport comms receive daemon */
static int dlm_recvd(void *data)
{
init_waitqueue_entry(&lowcomms_recv_waitq_head, current);
add_wait_queue(&lowcomms_recv_waitq, &lowcomms_recv_waitq_head);
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
if (read_list_empty())
cond_resched();
set_current_state(TASK_RUNNING);
process_sockets();
}
return 0;
}
static int write_and_state_lists_empty(void)
{
int status;
spin_lock_bh(&write_sockets_lock);
status = list_empty(&write_sockets);
spin_unlock_bh(&write_sockets_lock);
spin_lock_bh(&state_sockets_lock);
if (list_empty(&state_sockets) == 0)
status = 0;
spin_unlock_bh(&state_sockets_lock);
return status;
}
/* DLM Transport send daemon */
static int dlm_sendd(void *data)
{
init_waitqueue_entry(&lowcomms_send_waitq_head, current);
add_wait_queue(&lowcomms_send_waitq, &lowcomms_send_waitq_head);
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
if (write_and_state_lists_empty())
cond_resched();
set_current_state(TASK_RUNNING);
process_state_queue();
process_output_queue();
}
return 0;
}
static void daemons_stop(void)
{
kthread_stop(recv_task);
kthread_stop(send_task);
}
static int daemons_start(void)
{
struct task_struct *p;
int error;
p = kthread_run(dlm_recvd, NULL, "dlm_recvd");
error = IS_ERR(p);
if (error) {
log_print("can't start dlm_recvd %d", error);
return error;
}
recv_task = p;
p = kthread_run(dlm_sendd, NULL, "dlm_sendd");
error = IS_ERR(p);
if (error) {
log_print("can't start dlm_sendd %d", error);
kthread_stop(recv_task);
return error;
}
send_task = p;
return 0;
}
/*
* Return the largest buffer size we can cope with.
*/
int lowcomms_max_buffer_size(void)
{
return PAGE_CACHE_SIZE;
}
void dlm_lowcomms_stop(void)
{
int i;
/* Set all the flags to prevent any
socket activity.
*/
for (i = 0; i < conn_array_size; i++) {
if (connections[i])
connections[i]->flags |= 0xFF;
}
daemons_stop();
clean_writequeues();
for (i = 0; i < conn_array_size; i++) {
if (connections[i]) {
close_connection(connections[i], true);
if (connections[i]->othercon)
kmem_cache_free(con_cache, connections[i]->othercon);
kmem_cache_free(con_cache, connections[i]);
}
}
kfree(connections);
connections = NULL;
kmem_cache_destroy(con_cache);
}
/* This is quite likely to sleep... */
int dlm_lowcomms_start(void)
{
int error = 0;
error = -ENOMEM;
connections = kzalloc(sizeof(struct connection *) *
NODE_INCREMENT, GFP_KERNEL);
if (!connections)
goto out;
conn_array_size = NODE_INCREMENT;
if (dlm_our_addr(&dlm_local_addr, 0)) {
log_print("no local IP address has been set");
goto fail_free_conn;
}
if (!dlm_our_addr(&dlm_local_addr, 1)) {
log_print("This dlm comms module does not support multi-homed clustering");
goto fail_free_conn;
}
con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
__alignof__(struct connection), 0,
NULL, NULL);
if (!con_cache)
goto fail_free_conn;
/* Start listening */
error = listen_for_all();
if (error)
goto fail_unlisten;
error = daemons_start();
if (error)
goto fail_unlisten;
return 0;
fail_unlisten:
close_connection(connections[0], false);
kmem_cache_free(con_cache, connections[0]);
kmem_cache_destroy(con_cache);
fail_free_conn:
kfree(connections);
out:
return error;
}
/*
* Overrides for Emacs so that we follow Linus's tabbing style.
* Emacs will notice this stuff at the end of the file and automatically
* adjust the settings for this buffer only. This must remain at the end
* of the file.
* ---------------------------------------------------------------------------
* Local variables:
* c-file-style: "linux"
* End:
*/
