linux/drivers/connector/connector.c

488 lines
11 KiB
C

/*
* connector.c
*
* 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/moduleparam.h>
#include <linux/connector.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>
#include <net/sock.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
static u32 cn_idx = CN_IDX_CONNECTOR;
static u32 cn_val = CN_VAL_CONNECTOR;
module_param(cn_idx, uint, 0);
module_param(cn_val, uint, 0);
MODULE_PARM_DESC(cn_idx, "Connector's main device idx.");
MODULE_PARM_DESC(cn_val, "Connector's main device val.");
static DEFINE_MUTEX(notify_lock);
static LIST_HEAD(notify_list);
static struct cn_dev cdev;
static int cn_already_initialized;
/*
* msg->seq and msg->ack are used to determine message genealogy.
* When someone sends message it puts there locally unique sequence
* and random acknowledge numbers. Sequence number may be copied into
* nlmsghdr->nlmsg_seq too.
*
* Sequence number is incremented with each message to be sent.
*
* If we expect reply to our message then the sequence number in
* received message MUST be the same as in original message, and
* acknowledge number MUST be the same + 1.
*
* If we receive a message and its sequence number is not equal to the
* one we are expecting then it is a new message.
*
* If we receive a message and its sequence number is the same as one
* we are expecting but it's acknowledgement number is not equal to
* the acknowledgement number in the original message + 1, then it is
* a new message.
*
*/
int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
{
struct cn_callback_entry *__cbq;
unsigned int size;
struct sk_buff *skb;
struct nlmsghdr *nlh;
struct cn_msg *data;
struct cn_dev *dev = &cdev;
u32 group = 0;
int found = 0;
if (!__group) {
spin_lock_bh(&dev->cbdev->queue_lock);
list_for_each_entry(__cbq, &dev->cbdev->queue_list,
callback_entry) {
if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
found = 1;
group = __cbq->group;
break;
}
}
spin_unlock_bh(&dev->cbdev->queue_lock);
if (!found)
return -ENODEV;
} else {
group = __group;
}
if (!netlink_has_listeners(dev->nls, group))
return -ESRCH;
size = NLMSG_SPACE(sizeof(*msg) + msg->len);
skb = alloc_skb(size, gfp_mask);
if (!skb)
return -ENOMEM;
nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh));
data = NLMSG_DATA(nlh);
memcpy(data, msg, sizeof(*data) + msg->len);
NETLINK_CB(skb).dst_group = group;
return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
nlmsg_failure:
kfree_skb(skb);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(cn_netlink_send);
/*
* Callback helper - queues work and setup destructor for given data.
*/
static int cn_call_callback(struct sk_buff *skb)
{
struct cn_callback_entry *__cbq, *__new_cbq;
struct cn_dev *dev = &cdev;
struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(skb));
int err = -ENODEV;
spin_lock_bh(&dev->cbdev->queue_lock);
list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
if (likely(!work_pending(&__cbq->work) &&
__cbq->data.skb == NULL)) {
__cbq->data.skb = skb;
if (queue_cn_work(__cbq, &__cbq->work))
err = 0;
else
err = -EINVAL;
} else {
struct cn_callback_data *d;
err = -ENOMEM;
__new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
if (__new_cbq) {
d = &__new_cbq->data;
d->skb = skb;
d->callback = __cbq->data.callback;
d->free = __new_cbq;
__new_cbq->pdev = __cbq->pdev;
INIT_WORK(&__new_cbq->work,
&cn_queue_wrapper);
if (queue_cn_work(__new_cbq,
&__new_cbq->work))
err = 0;
else {
kfree(__new_cbq);
err = -EINVAL;
}
}
}
break;
}
}
spin_unlock_bh(&dev->cbdev->queue_lock);
return err;
}
/*
* Main netlink receiving function.
*
* It checks skb, netlink header and msg sizes, and calls callback helper.
*/
static void cn_rx_skb(struct sk_buff *__skb)
{
struct nlmsghdr *nlh;
int err;
struct sk_buff *skb;
skb = skb_get(__skb);
if (skb->len >= NLMSG_SPACE(0)) {
nlh = nlmsg_hdr(skb);
if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
skb->len < nlh->nlmsg_len ||
nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
kfree_skb(skb);
return;
}
err = cn_call_callback(skb);
if (err < 0)
kfree_skb(skb);
}
}
/*
* Notification routing.
*
* Gets id and checks if there are notification request for it's idx
* and val. If there are such requests notify the listeners with the
* given notify event.
*
*/
static void cn_notify(struct cb_id *id, u32 notify_event)
{
struct cn_ctl_entry *ent;
mutex_lock(&notify_lock);
list_for_each_entry(ent, &notify_list, notify_entry) {
int i;
struct cn_notify_req *req;
struct cn_ctl_msg *ctl = ent->msg;
int idx_found, val_found;
idx_found = val_found = 0;
req = (struct cn_notify_req *)ctl->data;
for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
if (id->idx >= req->first &&
id->idx < req->first + req->range) {
idx_found = 1;
break;
}
}
for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
if (id->val >= req->first &&
id->val < req->first + req->range) {
val_found = 1;
break;
}
}
if (idx_found && val_found) {
struct cn_msg m = { .ack = notify_event, };
memcpy(&m.id, id, sizeof(m.id));
cn_netlink_send(&m, ctl->group, GFP_KERNEL);
}
}
mutex_unlock(&notify_lock);
}
/*
* Callback add routing - adds callback with given ID and name.
* If there is registered callback with the same ID it will not be added.
*
* May sleep.
*/
int cn_add_callback(struct cb_id *id, char *name,
void (*callback)(struct cn_msg *, struct netlink_skb_parms *))
{
int err;
struct cn_dev *dev = &cdev;
if (!cn_already_initialized)
return -EAGAIN;
err = cn_queue_add_callback(dev->cbdev, name, id, callback);
if (err)
return err;
cn_notify(id, 0);
return 0;
}
EXPORT_SYMBOL_GPL(cn_add_callback);
/*
* Callback remove routing - removes callback
* with given ID.
* If there is no registered callback with given
* ID nothing happens.
*
* May sleep while waiting for reference counter to become zero.
*/
void cn_del_callback(struct cb_id *id)
{
struct cn_dev *dev = &cdev;
cn_queue_del_callback(dev->cbdev, id);
cn_notify(id, 1);
}
EXPORT_SYMBOL_GPL(cn_del_callback);
/*
* Checks two connector's control messages to be the same.
* Returns 1 if they are the same or if the first one is corrupted.
*/
static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
{
int i;
struct cn_notify_req *req1, *req2;
if (m1->idx_notify_num != m2->idx_notify_num)
return 0;
if (m1->val_notify_num != m2->val_notify_num)
return 0;
if (m1->len != m2->len)
return 0;
if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
m1->len)
return 1;
req1 = (struct cn_notify_req *)m1->data;
req2 = (struct cn_notify_req *)m2->data;
for (i = 0; i < m1->idx_notify_num; ++i) {
if (req1->first != req2->first || req1->range != req2->range)
return 0;
req1++;
req2++;
}
for (i = 0; i < m1->val_notify_num; ++i) {
if (req1->first != req2->first || req1->range != req2->range)
return 0;
req1++;
req2++;
}
return 1;
}
/*
* Main connector device's callback.
*
* Used for notification of a request's processing.
*/
static void cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
{
struct cn_ctl_msg *ctl;
struct cn_ctl_entry *ent;
u32 size;
if (msg->len < sizeof(*ctl))
return;
ctl = (struct cn_ctl_msg *)msg->data;
size = (sizeof(*ctl) + ((ctl->idx_notify_num +
ctl->val_notify_num) *
sizeof(struct cn_notify_req)));
if (msg->len != size)
return;
if (ctl->len + sizeof(*ctl) != msg->len)
return;
/*
* Remove notification.
*/
if (ctl->group == 0) {
struct cn_ctl_entry *n;
mutex_lock(&notify_lock);
list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
if (cn_ctl_msg_equals(ent->msg, ctl)) {
list_del(&ent->notify_entry);
kfree(ent);
}
}
mutex_unlock(&notify_lock);
return;
}
size += sizeof(*ent);
ent = kzalloc(size, GFP_KERNEL);
if (!ent)
return;
ent->msg = (struct cn_ctl_msg *)(ent + 1);
memcpy(ent->msg, ctl, size - sizeof(*ent));
mutex_lock(&notify_lock);
list_add(&ent->notify_entry, &notify_list);
mutex_unlock(&notify_lock);
}
static int cn_proc_show(struct seq_file *m, void *v)
{
struct cn_queue_dev *dev = cdev.cbdev;
struct cn_callback_entry *cbq;
seq_printf(m, "Name ID\n");
spin_lock_bh(&dev->queue_lock);
list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
seq_printf(m, "%-15s %u:%u\n",
cbq->id.name,
cbq->id.id.idx,
cbq->id.id.val);
}
spin_unlock_bh(&dev->queue_lock);
return 0;
}
static int cn_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, cn_proc_show, NULL);
}
static const struct file_operations cn_file_ops = {
.owner = THIS_MODULE,
.open = cn_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release
};
static int __devinit cn_init(void)
{
struct cn_dev *dev = &cdev;
int err;
dev->input = cn_rx_skb;
dev->id.idx = cn_idx;
dev->id.val = cn_val;
dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
CN_NETLINK_USERS + 0xf,
dev->input, NULL, THIS_MODULE);
if (!dev->nls)
return -EIO;
dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
if (!dev->cbdev) {
netlink_kernel_release(dev->nls);
return -EINVAL;
}
cn_already_initialized = 1;
err = cn_add_callback(&dev->id, "connector", &cn_callback);
if (err) {
cn_already_initialized = 0;
cn_queue_free_dev(dev->cbdev);
netlink_kernel_release(dev->nls);
return -EINVAL;
}
proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);
return 0;
}
static void __devexit cn_fini(void)
{
struct cn_dev *dev = &cdev;
cn_already_initialized = 0;
proc_net_remove(&init_net, "connector");
cn_del_callback(&dev->id);
cn_queue_free_dev(dev->cbdev);
netlink_kernel_release(dev->nls);
}
subsys_initcall(cn_init);
module_exit(cn_fini);