linux/drivers/connector/connector.c
David Fries 34470e0bfa connector: allow multiple messages to be sent in one packet
This increases the amount of bundling to reduce the number of packets
sent.  For the one wire use there can be multiple struct
w1_netlink_cmd in a struct w1_netlink_msg and multiple of those in
struct cn_msg, and with this change multiple of those in a struct
nlmsghdr, and at each level the len identifies there being multiple of
the next.

Signed-off-by: David Fries <David@Fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-27 13:56:21 -07:00

317 lines
7.5 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 <net/netlink.h>
#include <linux/moduleparam.h>
#include <linux/connector.h>
#include <linux/slab.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.");
MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);
static struct cn_dev cdev;
static int cn_already_initialized;
/*
* Sends mult (multiple) cn_msg at a time.
*
* 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 a 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.
*
* If msg->len != len, then additional cn_msg messages are expected following
* the first msg.
*
* The message is sent to, the portid if given, the group if given, both if
* both, or if both are zero then the group is looked up and sent there.
*/
int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, 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 (portid || __group) {
group = __group;
} else {
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;
}
if (!portid && !netlink_has_listeners(dev->nls, group))
return -ESRCH;
size = sizeof(*msg) + len;
skb = nlmsg_new(size, gfp_mask);
if (!skb)
return -ENOMEM;
nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0);
if (!nlh) {
kfree_skb(skb);
return -EMSGSIZE;
}
data = nlmsg_data(nlh);
memcpy(data, msg, size);
NETLINK_CB(skb).dst_group = group;
if (group)
return netlink_broadcast(dev->nls, skb, portid, group,
gfp_mask);
return netlink_unicast(dev->nls, skb, portid, !(gfp_mask&__GFP_WAIT));
}
EXPORT_SYMBOL_GPL(cn_netlink_send_mult);
/* same as cn_netlink_send_mult except msg->len is used for len */
int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
gfp_t gfp_mask)
{
return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask);
}
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 *i, *cbq = NULL;
struct cn_dev *dev = &cdev;
struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb));
struct netlink_skb_parms *nsp = &NETLINK_CB(skb);
int err = -ENODEV;
spin_lock_bh(&dev->cbdev->queue_lock);
list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) {
if (cn_cb_equal(&i->id.id, &msg->id)) {
atomic_inc(&i->refcnt);
cbq = i;
break;
}
}
spin_unlock_bh(&dev->cbdev->queue_lock);
if (cbq != NULL) {
cbq->callback(msg, nsp);
kfree_skb(skb);
cn_queue_release_callback(cbq);
err = 0;
}
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;
struct sk_buff *skb;
int len, err;
skb = skb_get(__skb);
if (skb->len >= NLMSG_HDRLEN) {
nlh = nlmsg_hdr(skb);
len = nlmsg_len(nlh);
if (len < (int)sizeof(struct cn_msg) ||
skb->len < nlh->nlmsg_len ||
len > CONNECTOR_MAX_MSG_SIZE) {
kfree_skb(skb);
return;
}
err = cn_call_callback(skb);
if (err < 0)
kfree_skb(skb);
}
}
/*
* 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, const 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;
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);
}
EXPORT_SYMBOL_GPL(cn_del_callback);
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 struct cn_dev cdev = {
.input = cn_rx_skb,
};
static int cn_init(void)
{
struct cn_dev *dev = &cdev;
struct netlink_kernel_cfg cfg = {
.groups = CN_NETLINK_USERS + 0xf,
.input = dev->input,
};
dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);
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;
proc_create("connector", S_IRUGO, init_net.proc_net, &cn_file_ops);
return 0;
}
static void cn_fini(void)
{
struct cn_dev *dev = &cdev;
cn_already_initialized = 0;
remove_proc_entry("connector", init_net.proc_net);
cn_queue_free_dev(dev->cbdev);
netlink_kernel_release(dev->nls);
}
subsys_initcall(cn_init);
module_exit(cn_fini);