[mirror_ubuntu-zesty-kernel.git] / drivers / hv / hv_utils_transport.c

/*
 * Kernel/userspace transport abstraction for Hyper-V util driver.
 *
 * Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * 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, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 */

#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/poll.h>

#include "hyperv_vmbus.h"
#include "hv_utils_transport.h"

static DEFINE_SPINLOCK(hvt_list_lock);
static struct list_head hvt_list = LIST_HEAD_INIT(hvt_list);

static void hvt_reset(struct hvutil_transport *hvt)
{
	kfree(hvt->outmsg);
	hvt->outmsg = NULL;
	hvt->outmsg_len = 0;
	if (hvt->on_reset)
		hvt->on_reset();
}

static ssize_t hvt_op_read(struct file *file, char __user *buf,
			   size_t count, loff_t *ppos)
{
	struct hvutil_transport *hvt;
	int ret;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 ||
				     hvt->mode != HVUTIL_TRANSPORT_CHARDEV))
		return -EINTR;

	mutex_lock(&hvt->lock);

	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
		ret = -EBADF;
		goto out_unlock;
	}

	if (!hvt->outmsg) {
		ret = -EAGAIN;
		goto out_unlock;
	}

	if (count < hvt->outmsg_len) {
		ret = -EINVAL;
		goto out_unlock;
	}

	if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
		ret = hvt->outmsg_len;
	else
		ret = -EFAULT;

	kfree(hvt->outmsg);
	hvt->outmsg = NULL;
	hvt->outmsg_len = 0;

	if (hvt->on_read)
		hvt->on_read();
	hvt->on_read = NULL;

out_unlock:
	mutex_unlock(&hvt->lock);
	return ret;
}

static ssize_t hvt_op_write(struct file *file, const char __user *buf,
			    size_t count, loff_t *ppos)
{
	struct hvutil_transport *hvt;
	u8 *inmsg;
	int ret;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	inmsg = memdup_user(buf, count);
	if (IS_ERR(inmsg))
		return PTR_ERR(inmsg);

	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
		ret = -EBADF;
	else
		ret = hvt->on_msg(inmsg, count);

	kfree(inmsg);

	return ret ? ret : count;
}

static unsigned int hvt_op_poll(struct file *file, poll_table *wait)
{
	struct hvutil_transport *hvt;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	poll_wait(file, &hvt->outmsg_q, wait);

	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
		return POLLERR | POLLHUP;

	if (hvt->outmsg_len > 0)
		return POLLIN | POLLRDNORM;

	return 0;
}

static int hvt_op_open(struct inode *inode, struct file *file)
{
	struct hvutil_transport *hvt;
	int ret = 0;
	bool issue_reset = false;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	mutex_lock(&hvt->lock);

	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
		ret = -EBADF;
	} else if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
		/*
		 * Switching to CHARDEV mode. We switch bach to INIT when
		 * device gets released.
		 */
		hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
	}
	else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
		/*
		 * We're switching from netlink communication to using char
		 * device. Issue the reset first.
		 */
		issue_reset = true;
		hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
	} else {
		ret = -EBUSY;
	}

	if (issue_reset)
		hvt_reset(hvt);

	mutex_unlock(&hvt->lock);

	return ret;
}

static void hvt_transport_free(struct hvutil_transport *hvt)
{
	misc_deregister(&hvt->mdev);
	kfree(hvt->outmsg);
	kfree(hvt);
}

static int hvt_op_release(struct inode *inode, struct file *file)
{
	struct hvutil_transport *hvt;
	int mode_old;

	hvt = container_of(file->f_op, struct hvutil_transport, fops);

	mutex_lock(&hvt->lock);
	mode_old = hvt->mode;
	if (hvt->mode != HVUTIL_TRANSPORT_DESTROY)
		hvt->mode = HVUTIL_TRANSPORT_INIT;
	/*
	 * Cleanup message buffers to avoid spurious messages when the daemon
	 * connects back.
	 */
	hvt_reset(hvt);
	mutex_unlock(&hvt->lock);

	if (mode_old == HVUTIL_TRANSPORT_DESTROY)
		hvt_transport_free(hvt);

	return 0;
}

static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
{
	struct hvutil_transport *hvt, *hvt_found = NULL;

	spin_lock(&hvt_list_lock);
	list_for_each_entry(hvt, &hvt_list, list) {
		if (hvt->cn_id.idx == msg->id.idx &&
		    hvt->cn_id.val == msg->id.val) {
			hvt_found = hvt;
			break;
		}
	}
	spin_unlock(&hvt_list_lock);
	if (!hvt_found) {
		pr_warn("hvt_cn_callback: spurious message received!\n");
		return;
	}

	/*
	 * Switching to NETLINK mode. Switching to CHARDEV happens when someone
	 * opens the device.
	 */
	mutex_lock(&hvt->lock);
	if (hvt->mode == HVUTIL_TRANSPORT_INIT)
		hvt->mode = HVUTIL_TRANSPORT_NETLINK;

	if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
		hvt_found->on_msg(msg->data, msg->len);
	else
		pr_warn("hvt_cn_callback: unexpected netlink message!\n");
	mutex_unlock(&hvt->lock);
}

int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len,
			  void (*on_read_cb)(void))
{
	struct cn_msg *cn_msg;
	int ret = 0;

	if (hvt->mode == HVUTIL_TRANSPORT_INIT ||
	    hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
		return -EINVAL;
	} else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
		cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
		if (!cn_msg)
			return -ENOMEM;
		cn_msg->id.idx = hvt->cn_id.idx;
		cn_msg->id.val = hvt->cn_id.val;
		cn_msg->len = len;
		memcpy(cn_msg->data, msg, len);
		ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
		kfree(cn_msg);
		/*
		 * We don't know when netlink messages are delivered but unlike
		 * in CHARDEV mode we're not blocked and we can send next
		 * messages right away.
		 */
		if (on_read_cb)
			on_read_cb();
		return ret;
	}
	/* HVUTIL_TRANSPORT_CHARDEV */
	mutex_lock(&hvt->lock);
	if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) {
		ret = -EINVAL;
		goto out_unlock;
	}

	if (hvt->outmsg) {
		/* Previous message wasn't received */
		ret = -EFAULT;
		goto out_unlock;
	}
	hvt->outmsg = kzalloc(len, GFP_KERNEL);
	if (hvt->outmsg) {
		memcpy(hvt->outmsg, msg, len);
		hvt->outmsg_len = len;
		hvt->on_read = on_read_cb;
		wake_up_interruptible(&hvt->outmsg_q);
	} else
		ret = -ENOMEM;
out_unlock:
	mutex_unlock(&hvt->lock);
	return ret;
}

struct hvutil_transport *hvutil_transport_init(const char *name,
					       u32 cn_idx, u32 cn_val,
					       int (*on_msg)(void *, int),
					       void (*on_reset)(void))
{
	struct hvutil_transport *hvt;

	hvt = kzalloc(sizeof(*hvt), GFP_KERNEL);
	if (!hvt)
		return NULL;

	hvt->cn_id.idx = cn_idx;
	hvt->cn_id.val = cn_val;

	hvt->mdev.minor = MISC_DYNAMIC_MINOR;
	hvt->mdev.name = name;

	hvt->fops.owner = THIS_MODULE;
	hvt->fops.read = hvt_op_read;
	hvt->fops.write = hvt_op_write;
	hvt->fops.poll = hvt_op_poll;
	hvt->fops.open = hvt_op_open;
	hvt->fops.release = hvt_op_release;

	hvt->mdev.fops = &hvt->fops;

	init_waitqueue_head(&hvt->outmsg_q);
	mutex_init(&hvt->lock);

	spin_lock(&hvt_list_lock);
	list_add(&hvt->list, &hvt_list);
	spin_unlock(&hvt_list_lock);

	hvt->on_msg = on_msg;
	hvt->on_reset = on_reset;

	if (misc_register(&hvt->mdev))
		goto err_free_hvt;

	/* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */
	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 &&
	    cn_add_callback(&hvt->cn_id, name, hvt_cn_callback))
		goto err_free_hvt;

	return hvt;

err_free_hvt:
	spin_lock(&hvt_list_lock);
	list_del(&hvt->list);
	spin_unlock(&hvt_list_lock);
	kfree(hvt);
	return NULL;
}

void hvutil_transport_destroy(struct hvutil_transport *hvt)
{
	int mode_old;

	mutex_lock(&hvt->lock);
	mode_old = hvt->mode;
	hvt->mode = HVUTIL_TRANSPORT_DESTROY;
	wake_up_interruptible(&hvt->outmsg_q);
	mutex_unlock(&hvt->lock);

	/*
	 * In case we were in 'chardev' mode we still have an open fd so we
	 * have to defer freeing the device. Netlink interface can be freed
	 * now.
	 */
	spin_lock(&hvt_list_lock);
	list_del(&hvt->list);
	spin_unlock(&hvt_list_lock);
	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0)
		cn_del_callback(&hvt->cn_id);

	if (mode_old != HVUTIL_TRANSPORT_CHARDEV)
		hvt_transport_free(hvt);
}
Commit	Line	Data
14b50f80 VK	1	/*
	2	* Kernel/userspace transport abstraction for Hyper-V util driver.
	3	*
	4	* Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
	5	*
	6	* This program is free software; you can redistribute it and/or modify it
	7	* under the terms of the GNU General Public License version 2 as published
	8	* by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful, but
	11	* WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	13	* NON INFRINGEMENT. See the GNU General Public License for more
	14	* details.
	15	*
	16	*/
	17
	18	#include <linux/slab.h>
	19	#include <linux/fs.h>
	20	#include <linux/poll.h>
	21
	22	#include "hyperv_vmbus.h"
	23	#include "hv_utils_transport.h"
	24
	25	static DEFINE_SPINLOCK(hvt_list_lock);
	26	static struct list_head hvt_list = LIST_HEAD_INIT(hvt_list);
	27
	28	static void hvt_reset(struct hvutil_transport *hvt)
	29	{
14b50f80 VK	30	kfree(hvt->outmsg);
	31	hvt->outmsg = NULL;
	32	hvt->outmsg_len = 0;
14b50f80 VK	33	if (hvt->on_reset)
	34	hvt->on_reset();
	35	}
	36
	37	static ssize_t hvt_op_read(struct file file, char __user buf,
	38	size_t count, loff_t *ppos)
	39	{
	40	struct hvutil_transport *hvt;
	41	int ret;
	42
	43	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	44
a1502566 VK	45	if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 \|\|
a1502566 VK	46	hvt->mode != HVUTIL_TRANSPORT_CHARDEV))
14b50f80 VK	47	return -EINTR;
14b50f80 VK	48
a72f3a4c	49	mutex_lock(&hvt->lock);
a1502566 VK	50
	51	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
	52	ret = -EBADF;
	53	goto out_unlock;
	54	}
	55
14b50f80 VK	56	if (!hvt->outmsg) {
	57	ret = -EAGAIN;
	58	goto out_unlock;
	59	}
	60
	61	if (count < hvt->outmsg_len) {
	62	ret = -EINVAL;
	63	goto out_unlock;
	64	}
	65
	66	if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
	67	ret = hvt->outmsg_len;
	68	else
	69	ret = -EFAULT;
	70
	71	kfree(hvt->outmsg);
	72	hvt->outmsg = NULL;
	73	hvt->outmsg_len = 0;
	74
e0fa3e5e VK	75	if (hvt->on_read)
	76	hvt->on_read();
	77	hvt->on_read = NULL;
	78
14b50f80	79	out_unlock:
a72f3a4c	80	mutex_unlock(&hvt->lock);
14b50f80 VK	81	return ret;
	82	}
	83
	84	static ssize_t hvt_op_write(struct file file, const char __user buf,
	85	size_t count, loff_t *ppos)
	86	{
	87	struct hvutil_transport *hvt;
	88	u8 *inmsg;
1f75338b	89	int ret;
14b50f80 VK	90
	91	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	92
b0035964 OH	93	inmsg = memdup_user(buf, count);
	94	if (IS_ERR(inmsg))
	95	return PTR_ERR(inmsg);
	96
a1502566 VK	97	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
	98	ret = -EBADF;
	99	else
	100	ret = hvt->on_msg(inmsg, count);
1f75338b	101
14b50f80 VK	102	kfree(inmsg);
14b50f80 VK	103
1f75338b	104	return ret ? ret : count;
14b50f80 VK	105	}
	106
	107	static unsigned int hvt_op_poll(struct file file, poll_table wait)
	108	{
	109	struct hvutil_transport *hvt;
	110
	111	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	112
	113	poll_wait(file, &hvt->outmsg_q, wait);
a1502566 VK	114
a1502566 VK	115	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
77b744a5	116	return POLLERR \| POLLHUP;
a1502566	117
14b50f80 VK	118	if (hvt->outmsg_len > 0)
	119	return POLLIN \| POLLRDNORM;
	120
	121	return 0;
	122	}
	123
	124	static int hvt_op_open(struct inode inode, struct file file)
	125	{
	126	struct hvutil_transport *hvt;
a1502566 VK	127	int ret = 0;
a1502566 VK	128	bool issue_reset = false;
14b50f80 VK	129
	130	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	131
a1502566 VK	132	mutex_lock(&hvt->lock);
	133
	134	if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
	135	ret = -EBADF;
	136	} else if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
	137	/*
	138	* Switching to CHARDEV mode. We switch bach to INIT when
	139	* device gets released.
	140	*/
14b50f80	141	hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
a1502566	142	}
14b50f80 VK	143	else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
	144	/*
	145	* We're switching from netlink communication to using char
	146	* device. Issue the reset first.
	147	*/
a1502566	148	issue_reset = true;
14b50f80	149	hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
a1502566 VK	150	} else {
	151	ret = -EBUSY;
	152	}
14b50f80	153
a1502566 VK	154	if (issue_reset)
	155	hvt_reset(hvt);
	156
	157	mutex_unlock(&hvt->lock);
	158
	159	return ret;
14b50f80 VK	160	}
14b50f80 VK	161
9420098a VK	162	static void hvt_transport_free(struct hvutil_transport *hvt)
	163	{
	164	misc_deregister(&hvt->mdev);
	165	kfree(hvt->outmsg);
	166	kfree(hvt);
	167	}
	168
14b50f80 VK	169	static int hvt_op_release(struct inode inode, struct file file)
	170	{
	171	struct hvutil_transport *hvt;
9420098a	172	int mode_old;
14b50f80 VK	173
	174	hvt = container_of(file->f_op, struct hvutil_transport, fops);
	175
a1502566	176	mutex_lock(&hvt->lock);
9420098a	177	mode_old = hvt->mode;
a1502566 VK	178	if (hvt->mode != HVUTIL_TRANSPORT_DESTROY)
a1502566 VK	179	hvt->mode = HVUTIL_TRANSPORT_INIT;
14b50f80 VK	180	/*
	181	* Cleanup message buffers to avoid spurious messages when the daemon
	182	* connects back.
	183	*/
	184	hvt_reset(hvt);
a1502566	185	mutex_unlock(&hvt->lock);
14b50f80	186
9420098a VK	187	if (mode_old == HVUTIL_TRANSPORT_DESTROY)
	188	hvt_transport_free(hvt);
	189
14b50f80 VK	190	return 0;
	191	}
	192
	193	static void hvt_cn_callback(struct cn_msg msg, struct netlink_skb_parms nsp)
	194	{
	195	struct hvutil_transport hvt, hvt_found = NULL;
	196
	197	spin_lock(&hvt_list_lock);
	198	list_for_each_entry(hvt, &hvt_list, list) {
	199	if (hvt->cn_id.idx == msg->id.idx &&
	200	hvt->cn_id.val == msg->id.val) {
	201	hvt_found = hvt;
	202	break;
	203	}
	204	}
	205	spin_unlock(&hvt_list_lock);
	206	if (!hvt_found) {
	207	pr_warn("hvt_cn_callback: spurious message received!\n");
	208	return;
	209	}
	210
	211	/*
	212	* Switching to NETLINK mode. Switching to CHARDEV happens when someone
	213	* opens the device.
	214	*/
a1502566	215	mutex_lock(&hvt->lock);
14b50f80 VK	216	if (hvt->mode == HVUTIL_TRANSPORT_INIT)
	217	hvt->mode = HVUTIL_TRANSPORT_NETLINK;
	218
	219	if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
	220	hvt_found->on_msg(msg->data, msg->len);
	221	else
	222	pr_warn("hvt_cn_callback: unexpected netlink message!\n");
a1502566	223	mutex_unlock(&hvt->lock);
14b50f80 VK	224	}
14b50f80 VK	225
e0fa3e5e VK	226	int hvutil_transport_send(struct hvutil_transport hvt, void msg, int len,
e0fa3e5e VK	227	void (*on_read_cb)(void))
14b50f80 VK	228	{
	229	struct cn_msg *cn_msg;
	230	int ret = 0;
	231
a1502566 VK	232	if (hvt->mode == HVUTIL_TRANSPORT_INIT \|\|
a1502566 VK	233	hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
14b50f80 VK	234	return -EINVAL;
	235	} else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
	236	cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
9dd6a064	237	if (!cn_msg)
14b50f80 VK	238	return -ENOMEM;
	239	cn_msg->id.idx = hvt->cn_id.idx;
	240	cn_msg->id.val = hvt->cn_id.val;
	241	cn_msg->len = len;
	242	memcpy(cn_msg->data, msg, len);
	243	ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
	244	kfree(cn_msg);
e0fa3e5e VK	245	/*
	246	* We don't know when netlink messages are delivered but unlike
	247	* in CHARDEV mode we're not blocked and we can send next
	248	* messages right away.
	249	*/
	250	if (on_read_cb)
	251	on_read_cb();
14b50f80 VK	252	return ret;
	253	}
	254	/* HVUTIL_TRANSPORT_CHARDEV */
a72f3a4c	255	mutex_lock(&hvt->lock);
a1502566 VK	256	if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) {
	257	ret = -EINVAL;
	258	goto out_unlock;
	259	}
	260
14b50f80 VK	261	if (hvt->outmsg) {
	262	/* Previous message wasn't received */
	263	ret = -EFAULT;
	264	goto out_unlock;
	265	}
	266	hvt->outmsg = kzalloc(len, GFP_KERNEL);
cdc0c0c9 OH	267	if (hvt->outmsg) {
	268	memcpy(hvt->outmsg, msg, len);
	269	hvt->outmsg_len = len;
e0fa3e5e	270	hvt->on_read = on_read_cb;
cdc0c0c9 OH	271	wake_up_interruptible(&hvt->outmsg_q);
	272	} else
	273	ret = -ENOMEM;
14b50f80	274	out_unlock:
a72f3a4c	275	mutex_unlock(&hvt->lock);
14b50f80 VK	276	return ret;
	277	}
	278
	279	struct hvutil_transport hvutil_transport_init(const char name,
	280	u32 cn_idx, u32 cn_val,
	281	int (on_msg)(void , int),
	282	void (*on_reset)(void))
	283	{
	284	struct hvutil_transport *hvt;
	285
	286	hvt = kzalloc(sizeof(*hvt), GFP_KERNEL);
	287	if (!hvt)
	288	return NULL;
	289
	290	hvt->cn_id.idx = cn_idx;
	291	hvt->cn_id.val = cn_val;
	292
	293	hvt->mdev.minor = MISC_DYNAMIC_MINOR;
	294	hvt->mdev.name = name;
	295
	296	hvt->fops.owner = THIS_MODULE;
	297	hvt->fops.read = hvt_op_read;
	298	hvt->fops.write = hvt_op_write;
	299	hvt->fops.poll = hvt_op_poll;
	300	hvt->fops.open = hvt_op_open;
	301	hvt->fops.release = hvt_op_release;
	302
	303	hvt->mdev.fops = &hvt->fops;
	304
	305	init_waitqueue_head(&hvt->outmsg_q);
a72f3a4c	306	mutex_init(&hvt->lock);
14b50f80 VK	307
	308	spin_lock(&hvt_list_lock);
	309	list_add(&hvt->list, &hvt_list);
	310	spin_unlock(&hvt_list_lock);
	311
	312	hvt->on_msg = on_msg;
	313	hvt->on_reset = on_reset;
	314
	315	if (misc_register(&hvt->mdev))
	316	goto err_free_hvt;
	317
	318	/* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */
	319	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 &&
	320	cn_add_callback(&hvt->cn_id, name, hvt_cn_callback))
	321	goto err_free_hvt;
	322
	323	return hvt;
	324
	325	err_free_hvt:
e66853b0 AN	326	spin_lock(&hvt_list_lock);
	327	list_del(&hvt->list);
	328	spin_unlock(&hvt_list_lock);
14b50f80 VK	329	kfree(hvt);
	330	return NULL;
	331	}
	332
	333	void hvutil_transport_destroy(struct hvutil_transport *hvt)
	334	{
9420098a VK	335	int mode_old;
9420098a VK	336
a1502566	337	mutex_lock(&hvt->lock);
9420098a	338	mode_old = hvt->mode;
a1502566 VK	339	hvt->mode = HVUTIL_TRANSPORT_DESTROY;
	340	wake_up_interruptible(&hvt->outmsg_q);
	341	mutex_unlock(&hvt->lock);
	342
9420098a VK	343	/*
	344	* In case we were in 'chardev' mode we still have an open fd so we
	345	* have to defer freeing the device. Netlink interface can be freed
	346	* now.
	347	*/
14b50f80 VK	348	spin_lock(&hvt_list_lock);
	349	list_del(&hvt->list);
	350	spin_unlock(&hvt_list_lock);
	351	if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0)
	352	cn_del_callback(&hvt->cn_id);
9420098a VK	353
	354	if (mode_old != HVUTIL_TRANSPORT_CHARDEV)
	355	hvt_transport_free(hvt);
14b50f80	356	}