drivers/hv/hv_utils_transport.c - linux - Git at Google

 /*
  * 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 __poll_t 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 EPOLLERR | EPOLLHUP;

 	if (hvt->outmsg_len > 0)
 		return EPOLLIN | EPOLLRDNORM;

 	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);

 	if (mode_old == HVUTIL_TRANSPORT_DESTROY)
 		complete(&hvt->release);

 	mutex_unlock(&hvt->lock);

 	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);
 	init_completion(&hvt->release);

 	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)
 		wait_for_completion(&hvt->release);

 	hvt_transport_free(hvt);
 }
	/*
	* 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 __poll_t 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 EPOLLERR \| EPOLLHUP;

	if (hvt->outmsg_len > 0)
	return EPOLLIN \| EPOLLRDNORM;

	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);

	if (mode_old == HVUTIL_TRANSPORT_DESTROY)
	complete(&hvt->release);

	mutex_unlock(&hvt->lock);

	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);
	init_completion(&hvt->release);

	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)
	wait_for_completion(&hvt->release);

	hvt_transport_free(hvt);
	}