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