net/wimax/op-msg.c - third_party/linux - Git at Google

 /*
  * Linux WiMAX
  * Generic messaging interface between userspace and driver/device
  *
  *
  * Copyright (C) 2007-2008 Intel Corporation <linux-wimax@intel.com>
  * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.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.  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., 51 Franklin Street, Fifth Floor, Boston, MA
  * 02110-1301, USA.
  *
  *
  * This implements a direct communication channel between user space and
  * the driver/device, by which free form messages can be sent back and
  * forth.
  *
  * This is intended for device-specific features, vendor quirks, etc.
  *
  * See include/net/wimax.h
  *
  * GENERIC NETLINK ENCODING AND CAPACITY
  *
  * A destination "pipe name" is added to each message; it is up to the
  * drivers to assign or use those names (if using them at all).
  *
  * Messages are encoded as a binary netlink attribute using nla_put()
  * using type NLA_UNSPEC (as some versions of libnl still in
  * deployment don't yet understand NLA_BINARY).
  *
  * The maximum capacity of this transport is PAGESIZE per message (so
  * the actual payload will be bit smaller depending on the
  * netlink/generic netlink attributes and headers).
  *
  * RECEPTION OF MESSAGES
  *
  * When a message is received from user space, it is passed verbatim
  * to the driver calling wimax_dev->op_msg_from_user(). The return
  * value from this function is passed back to user space as an ack
  * over the generic netlink protocol.
  *
  * The stack doesn't do any processing or interpretation of these
  * messages.
  *
  * SENDING MESSAGES
  *
  * Messages can be sent with wimax_msg().
  *
  * If the message delivery needs to happen on a different context to
  * that of its creation, wimax_msg_alloc() can be used to get a
  * pointer to the message that can be delivered later on with
  * wimax_msg_send().
  *
  * ROADMAP
  *
  * wimax_gnl_doit_msg_from_user()    Process a message from user space
  *   wimax_dev_get_by_genl_info()
  *   wimax_dev->op_msg_from_user()   Delivery of message to the driver
  *
  * wimax_msg()                       Send a message to user space
  *   wimax_msg_alloc()
  *   wimax_msg_send()
  */
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <net/genetlink.h>
 #include <linux/netdevice.h>
 #include <linux/wimax.h>
 #include <linux/security.h>
 #include <linux/export.h>
 #include "wimax-internal.h"


 #define D_SUBMODULE op_msg
 #include "debug-levels.h"


 /**
  * wimax_msg_alloc - Create a new skb for sending a message to userspace
  *
  * @wimax_dev: WiMAX device descriptor
  * @pipe_name: "named pipe" the message will be sent to
  * @msg: pointer to the message data to send
  * @size: size of the message to send (in bytes), including the header.
  * @gfp_flags: flags for memory allocation.
  *
  * Returns: %0 if ok, negative errno code on error
  *
  * Description:
  *
  * Allocates an skb that will contain the message to send to user
  * space over the messaging pipe and initializes it, copying the
  * payload.
  *
  * Once this call is done, you can deliver it with
  * wimax_msg_send().
  *
  * IMPORTANT:
  *
  * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
  * wimax_msg_send() depends on skb->data being placed at the
  * beginning of the user message.
  *
  * Unlike other WiMAX stack calls, this call can be used way early,
  * even before wimax_dev_add() is called, as long as the
  * wimax_dev->net_dev pointer is set to point to a proper
  * net_dev. This is so that drivers can use it early in case they need
  * to send stuff around or communicate with user space.
  */
 struct sk_buff *wimax_msg_alloc(struct wimax_dev *wimax_dev,
 				const char *pipe_name,
 				const void *msg, size_t size,
 				gfp_t gfp_flags)
 {
 	int result;
 	struct device *dev = wimax_dev_to_dev(wimax_dev);
 	size_t msg_size;
 	void *genl_msg;
 	struct sk_buff *skb;

 	msg_size = nla_total_size(size)
 		+ nla_total_size(sizeof(u32))
 		+ (pipe_name ? nla_total_size(strlen(pipe_name)) : 0);
 	result = -ENOMEM;
 	skb = genlmsg_new(msg_size, gfp_flags);
 	if (skb == NULL)
 		goto error_new;
 	genl_msg = genlmsg_put(skb, 0, 0, &wimax_gnl_family,
 			       0, WIMAX_GNL_OP_MSG_TO_USER);
 	if (genl_msg == NULL) {
 		dev_err(dev, "no memory to create generic netlink message\n");
 		goto error_genlmsg_put;
 	}
 	result = nla_put_u32(skb, WIMAX_GNL_MSG_IFIDX,
 			     wimax_dev->net_dev->ifindex);
 	if (result < 0) {
 		dev_err(dev, "no memory to add ifindex attribute\n");
 		goto error_nla_put;
 	}
 	if (pipe_name) {
 		result = nla_put_string(skb, WIMAX_GNL_MSG_PIPE_NAME,
 					pipe_name);
 		if (result < 0) {
 			dev_err(dev, "no memory to add pipe_name attribute\n");
 			goto error_nla_put;
 		}
 	}
 	result = nla_put(skb, WIMAX_GNL_MSG_DATA, size, msg);
 	if (result < 0) {
 		dev_err(dev, "no memory to add payload (msg %p size %zu) in "
 			"attribute: %d\n", msg, size, result);
 		goto error_nla_put;
 	}
 	genlmsg_end(skb, genl_msg);
 	return skb;

 error_nla_put:
 error_genlmsg_put:
 error_new:
 	nlmsg_free(skb);
 	return ERR_PTR(result);
 }
 EXPORT_SYMBOL_GPL(wimax_msg_alloc);


 /**
  * wimax_msg_data_len - Return a pointer and size of a message's payload
  *
  * @msg: Pointer to a message created with wimax_msg_alloc()
  * @size: Pointer to where to store the message's size
  *
  * Returns the pointer to the message data.
  */
 const void *wimax_msg_data_len(struct sk_buff *msg, size_t *size)
 {
 	struct nlmsghdr *nlh = (void *) msg->head;
 	struct nlattr *nla;

 	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
 			      WIMAX_GNL_MSG_DATA);
 	if (nla == NULL) {
 		pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
 		return NULL;
 	}
 	*size = nla_len(nla);
 	return nla_data(nla);
 }
 EXPORT_SYMBOL_GPL(wimax_msg_data_len);


 /**
  * wimax_msg_data - Return a pointer to a message's payload
  *
  * @msg: Pointer to a message created with wimax_msg_alloc()
  */
 const void *wimax_msg_data(struct sk_buff *msg)
 {
 	struct nlmsghdr *nlh = (void *) msg->head;
 	struct nlattr *nla;

 	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
 			      WIMAX_GNL_MSG_DATA);
 	if (nla == NULL) {
 		pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
 		return NULL;
 	}
 	return nla_data(nla);
 }
 EXPORT_SYMBOL_GPL(wimax_msg_data);


 /**
  * wimax_msg_len - Return a message's payload length
  *
  * @msg: Pointer to a message created with wimax_msg_alloc()
  */
 ssize_t wimax_msg_len(struct sk_buff *msg)
 {
 	struct nlmsghdr *nlh = (void *) msg->head;
 	struct nlattr *nla;

 	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
 			      WIMAX_GNL_MSG_DATA);
 	if (nla == NULL) {
 		pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
 		return -EINVAL;
 	}
 	return nla_len(nla);
 }
 EXPORT_SYMBOL_GPL(wimax_msg_len);


 /**
  * wimax_msg_send - Send a pre-allocated message to user space
  *
  * @wimax_dev: WiMAX device descriptor
  *
  * @skb: &struct sk_buff returned by wimax_msg_alloc(). Note the
  *     ownership of @skb is transferred to this function.
  *
  * Returns: 0 if ok, < 0 errno code on error
  *
  * Description:
  *
  * Sends a free-form message that was preallocated with
  * wimax_msg_alloc() and filled up.
  *
  * Assumes that once you pass an skb to this function for sending, it
  * owns it and will release it when done (on success).
  *
  * IMPORTANT:
  *
  * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
  * wimax_msg_send() depends on skb->data being placed at the
  * beginning of the user message.
  *
  * Unlike other WiMAX stack calls, this call can be used way early,
  * even before wimax_dev_add() is called, as long as the
  * wimax_dev->net_dev pointer is set to point to a proper
  * net_dev. This is so that drivers can use it early in case they need
  * to send stuff around or communicate with user space.
  */
 int wimax_msg_send(struct wimax_dev *wimax_dev, struct sk_buff *skb)
 {
 	struct device *dev = wimax_dev_to_dev(wimax_dev);
 	void *msg = skb->data;
 	size_t size = skb->len;
 	might_sleep();

 	d_printf(1, dev, "CTX: wimax msg, %zu bytes\n", size);
 	d_dump(2, dev, msg, size);
 	genlmsg_multicast(&wimax_gnl_family, skb, 0, 0, GFP_KERNEL);
 	d_printf(1, dev, "CTX: genl multicast done\n");
 	return 0;
 }
 EXPORT_SYMBOL_GPL(wimax_msg_send);


 /**
  * wimax_msg - Send a message to user space
  *
  * @wimax_dev: WiMAX device descriptor (properly referenced)
  * @pipe_name: "named pipe" the message will be sent to
  * @buf: pointer to the message to send.
  * @size: size of the buffer pointed to by @buf (in bytes).
  * @gfp_flags: flags for memory allocation.
  *
  * Returns: %0 if ok, negative errno code on error.
  *
  * Description:
  *
  * Sends a free-form message to user space on the device @wimax_dev.
  *
  * NOTES:
  *
  * Once the @skb is given to this function, who will own it and will
  * release it when done (unless it returns error).
  */
 int wimax_msg(struct wimax_dev *wimax_dev, const char *pipe_name,
 	      const void *buf, size_t size, gfp_t gfp_flags)
 {
 	int result = -ENOMEM;
 	struct sk_buff *skb;

 	skb = wimax_msg_alloc(wimax_dev, pipe_name, buf, size, gfp_flags);
 	if (IS_ERR(skb))
 		result = PTR_ERR(skb);
 	else
 		result = wimax_msg_send(wimax_dev, skb);
 	return result;
 }
 EXPORT_SYMBOL_GPL(wimax_msg);

 /*
  * Relays a message from user space to the driver
  *
  * The skb is passed to the driver-specific function with the netlink
  * and generic netlink headers already stripped.
  *
  * This call will block while handling/relaying the message.
  */
 int wimax_gnl_doit_msg_from_user(struct sk_buff *skb, struct genl_info *info)
 {
 	int result, ifindex;
 	struct wimax_dev *wimax_dev;
 	struct device *dev;
 	struct nlmsghdr *nlh = info->nlhdr;
 	char *pipe_name;
 	void *msg_buf;
 	size_t msg_len;

 	might_sleep();
 	d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
 	result = -ENODEV;
 	if (info->attrs[WIMAX_GNL_MSG_IFIDX] == NULL) {
 		pr_err("WIMAX_GNL_MSG_FROM_USER: can't find IFIDX attribute\n");
 		goto error_no_wimax_dev;
 	}
 	ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_IFIDX]);
 	wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
 	if (wimax_dev == NULL)
 		goto error_no_wimax_dev;
 	dev = wimax_dev_to_dev(wimax_dev);

 	/* Unpack arguments */
 	result = -EINVAL;
 	if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
 		dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
 			"attribute\n");
 		goto error_no_data;
 	}
 	msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
 	msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);

 	if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
 		pipe_name = NULL;
 	else {
 		struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
 		size_t attr_len = nla_len(attr);
 		/* libnl-1.1 does not yet support NLA_NUL_STRING */
 		result = -ENOMEM;
 		pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
 		if (pipe_name == NULL)
 			goto error_alloc;
 		pipe_name[attr_len] = 0;
 	}
 	mutex_lock(&wimax_dev->mutex);
 	result = wimax_dev_is_ready(wimax_dev);
 	if (result == -ENOMEDIUM)
 		result = 0;
 	if (result < 0)
 		goto error_not_ready;
 	result = -ENOSYS;
 	if (wimax_dev->op_msg_from_user == NULL)
 		goto error_noop;

 	d_printf(1, dev,
 		 "CRX: nlmsghdr len %u type %u flags 0x%04x seq 0x%x pid %u\n",
 		 nlh->nlmsg_len, nlh->nlmsg_type, nlh->nlmsg_flags,
 		 nlh->nlmsg_seq, nlh->nlmsg_pid);
 	d_printf(1, dev, "CRX: wimax message %zu bytes\n", msg_len);
 	d_dump(2, dev, msg_buf, msg_len);

 	result = wimax_dev->op_msg_from_user(wimax_dev, pipe_name,
 					     msg_buf, msg_len, info);
 error_noop:
 error_not_ready:
 	mutex_unlock(&wimax_dev->mutex);
 error_alloc:
 	kfree(pipe_name);
 error_no_data:
 	dev_put(wimax_dev->net_dev);
 error_no_wimax_dev:
 	d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
 	return result;
 }
	/*
	* Linux WiMAX
	* Generic messaging interface between userspace and driver/device
	*
	*
	* Copyright (C) 2007-2008 Intel Corporation <linux-wimax@intel.com>
	* Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.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. 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., 51 Franklin Street, Fifth Floor, Boston, MA
	* 02110-1301, USA.
	*
	*
	* This implements a direct communication channel between user space and
	* the driver/device, by which free form messages can be sent back and
	* forth.
	*
	* This is intended for device-specific features, vendor quirks, etc.
	*
	* See include/net/wimax.h
	*
	* GENERIC NETLINK ENCODING AND CAPACITY
	*
	* A destination "pipe name" is added to each message; it is up to the
	* drivers to assign or use those names (if using them at all).
	*
	* Messages are encoded as a binary netlink attribute using nla_put()
	* using type NLA_UNSPEC (as some versions of libnl still in
	* deployment don't yet understand NLA_BINARY).
	*
	* The maximum capacity of this transport is PAGESIZE per message (so
	* the actual payload will be bit smaller depending on the
	* netlink/generic netlink attributes and headers).
	*
	* RECEPTION OF MESSAGES
	*
	* When a message is received from user space, it is passed verbatim
	* to the driver calling wimax_dev->op_msg_from_user(). The return
	* value from this function is passed back to user space as an ack
	* over the generic netlink protocol.
	*
	* The stack doesn't do any processing or interpretation of these
	* messages.
	*
	* SENDING MESSAGES
	*
	* Messages can be sent with wimax_msg().
	*
	* If the message delivery needs to happen on a different context to
	* that of its creation, wimax_msg_alloc() can be used to get a
	* pointer to the message that can be delivered later on with
	* wimax_msg_send().
	*
	* ROADMAP
	*
	* wimax_gnl_doit_msg_from_user() Process a message from user space
	* wimax_dev_get_by_genl_info()
	* wimax_dev->op_msg_from_user() Delivery of message to the driver
	*
	* wimax_msg() Send a message to user space
	* wimax_msg_alloc()
	* wimax_msg_send()
	*/
	#include <linux/device.h>
	#include <linux/slab.h>
	#include <net/genetlink.h>
	#include <linux/netdevice.h>
	#include <linux/wimax.h>
	#include <linux/security.h>
	#include <linux/export.h>
	#include "wimax-internal.h"


	#define D_SUBMODULE op_msg
	#include "debug-levels.h"


	/**
	* wimax_msg_alloc - Create a new skb for sending a message to userspace
	*
	* @wimax_dev: WiMAX device descriptor
	* @pipe_name: "named pipe" the message will be sent to
	* @msg: pointer to the message data to send
	* @size: size of the message to send (in bytes), including the header.
	* @gfp_flags: flags for memory allocation.
	*
	* Returns: %0 if ok, negative errno code on error
	*
	* Description:
	*
	* Allocates an skb that will contain the message to send to user
	* space over the messaging pipe and initializes it, copying the
	* payload.
	*
	* Once this call is done, you can deliver it with
	* wimax_msg_send().
	*
	* IMPORTANT:
	*
	* Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
	* wimax_msg_send() depends on skb->data being placed at the
	* beginning of the user message.
	*
	* Unlike other WiMAX stack calls, this call can be used way early,
	* even before wimax_dev_add() is called, as long as the
	* wimax_dev->net_dev pointer is set to point to a proper
	* net_dev. This is so that drivers can use it early in case they need
	* to send stuff around or communicate with user space.
	*/
	struct sk_buff wimax_msg_alloc(struct wimax_dev wimax_dev,
	const char *pipe_name,
	const void *msg, size_t size,
	gfp_t gfp_flags)
	{
	int result;
	struct device *dev = wimax_dev_to_dev(wimax_dev);
	size_t msg_size;
	void *genl_msg;
	struct sk_buff *skb;

	msg_size = nla_total_size(size)
	+ nla_total_size(sizeof(u32))
	+ (pipe_name ? nla_total_size(strlen(pipe_name)) : 0);
	result = -ENOMEM;
	skb = genlmsg_new(msg_size, gfp_flags);
	if (skb == NULL)
	goto error_new;
	genl_msg = genlmsg_put(skb, 0, 0, &wimax_gnl_family,
	0, WIMAX_GNL_OP_MSG_TO_USER);
	if (genl_msg == NULL) {
	dev_err(dev, "no memory to create generic netlink message\n");
	goto error_genlmsg_put;
	}
	result = nla_put_u32(skb, WIMAX_GNL_MSG_IFIDX,
	wimax_dev->net_dev->ifindex);
	if (result < 0) {
	dev_err(dev, "no memory to add ifindex attribute\n");
	goto error_nla_put;
	}
	if (pipe_name) {
	result = nla_put_string(skb, WIMAX_GNL_MSG_PIPE_NAME,
	pipe_name);
	if (result < 0) {
	dev_err(dev, "no memory to add pipe_name attribute\n");
	goto error_nla_put;
	}
	}
	result = nla_put(skb, WIMAX_GNL_MSG_DATA, size, msg);
	if (result < 0) {
	dev_err(dev, "no memory to add payload (msg %p size %zu) in "
	"attribute: %d\n", msg, size, result);
	goto error_nla_put;
	}
	genlmsg_end(skb, genl_msg);
	return skb;

	error_nla_put:
	error_genlmsg_put:
	error_new:
	nlmsg_free(skb);
	return ERR_PTR(result);
	}
	EXPORT_SYMBOL_GPL(wimax_msg_alloc);


	/**
	* wimax_msg_data_len - Return a pointer and size of a message's payload
	*
	* @msg: Pointer to a message created with wimax_msg_alloc()
	* @size: Pointer to where to store the message's size
	*
	* Returns the pointer to the message data.
	*/
	const void wimax_msg_data_len(struct sk_buff msg, size_t *size)
	{
	struct nlmsghdr nlh = (void ) msg->head;
	struct nlattr *nla;

	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
	WIMAX_GNL_MSG_DATA);
	if (nla == NULL) {
	pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
	return NULL;
	}
	*size = nla_len(nla);
	return nla_data(nla);
	}
	EXPORT_SYMBOL_GPL(wimax_msg_data_len);


	/**
	* wimax_msg_data - Return a pointer to a message's payload
	*
	* @msg: Pointer to a message created with wimax_msg_alloc()
	*/
	const void wimax_msg_data(struct sk_buff msg)
	{
	struct nlmsghdr nlh = (void ) msg->head;
	struct nlattr *nla;

	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
	WIMAX_GNL_MSG_DATA);
	if (nla == NULL) {
	pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
	return NULL;
	}
	return nla_data(nla);
	}
	EXPORT_SYMBOL_GPL(wimax_msg_data);


	/**
	* wimax_msg_len - Return a message's payload length
	*
	* @msg: Pointer to a message created with wimax_msg_alloc()
	*/
	ssize_t wimax_msg_len(struct sk_buff *msg)
	{
	struct nlmsghdr nlh = (void ) msg->head;
	struct nlattr *nla;

	nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
	WIMAX_GNL_MSG_DATA);
	if (nla == NULL) {
	pr_err("Cannot find attribute WIMAX_GNL_MSG_DATA\n");
	return -EINVAL;
	}
	return nla_len(nla);
	}
	EXPORT_SYMBOL_GPL(wimax_msg_len);


	/**
	* wimax_msg_send - Send a pre-allocated message to user space
	*
	* @wimax_dev: WiMAX device descriptor
	*
	* @skb: &struct sk_buff returned by wimax_msg_alloc(). Note the
	* ownership of @skb is transferred to this function.
	*
	* Returns: 0 if ok, < 0 errno code on error
	*
	* Description:
	*
	* Sends a free-form message that was preallocated with
	* wimax_msg_alloc() and filled up.
	*
	* Assumes that once you pass an skb to this function for sending, it
	* owns it and will release it when done (on success).
	*
	* IMPORTANT:
	*
	* Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
	* wimax_msg_send() depends on skb->data being placed at the
	* beginning of the user message.
	*
	* Unlike other WiMAX stack calls, this call can be used way early,
	* even before wimax_dev_add() is called, as long as the
	* wimax_dev->net_dev pointer is set to point to a proper
	* net_dev. This is so that drivers can use it early in case they need
	* to send stuff around or communicate with user space.
	*/
	int wimax_msg_send(struct wimax_dev wimax_dev, struct sk_buff skb)
	{
	struct device *dev = wimax_dev_to_dev(wimax_dev);
	void *msg = skb->data;
	size_t size = skb->len;
	might_sleep();

	d_printf(1, dev, "CTX: wimax msg, %zu bytes\n", size);
	d_dump(2, dev, msg, size);
	genlmsg_multicast(&wimax_gnl_family, skb, 0, 0, GFP_KERNEL);
	d_printf(1, dev, "CTX: genl multicast done\n");
	return 0;
	}
	EXPORT_SYMBOL_GPL(wimax_msg_send);


	/**
	* wimax_msg - Send a message to user space
	*
	* @wimax_dev: WiMAX device descriptor (properly referenced)
	* @pipe_name: "named pipe" the message will be sent to
	* @buf: pointer to the message to send.
	* @size: size of the buffer pointed to by @buf (in bytes).
	* @gfp_flags: flags for memory allocation.
	*
	* Returns: %0 if ok, negative errno code on error.
	*
	* Description:
	*
	* Sends a free-form message to user space on the device @wimax_dev.
	*
	* NOTES:
	*
	* Once the @skb is given to this function, who will own it and will
	* release it when done (unless it returns error).
	*/
	int wimax_msg(struct wimax_dev wimax_dev, const char pipe_name,
	const void *buf, size_t size, gfp_t gfp_flags)
	{
	int result = -ENOMEM;
	struct sk_buff *skb;

	skb = wimax_msg_alloc(wimax_dev, pipe_name, buf, size, gfp_flags);
	if (IS_ERR(skb))
	result = PTR_ERR(skb);
	else
	result = wimax_msg_send(wimax_dev, skb);
	return result;
	}
	EXPORT_SYMBOL_GPL(wimax_msg);

	/*
	* Relays a message from user space to the driver
	*
	* The skb is passed to the driver-specific function with the netlink
	* and generic netlink headers already stripped.
	*
	* This call will block while handling/relaying the message.
	*/
	int wimax_gnl_doit_msg_from_user(struct sk_buff skb, struct genl_info info)
	{
	int result, ifindex;
	struct wimax_dev *wimax_dev;
	struct device *dev;
	struct nlmsghdr *nlh = info->nlhdr;
	char *pipe_name;
	void *msg_buf;
	size_t msg_len;

	might_sleep();
	d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
	result = -ENODEV;
	if (info->attrs[WIMAX_GNL_MSG_IFIDX] == NULL) {
	pr_err("WIMAX_GNL_MSG_FROM_USER: can't find IFIDX attribute\n");
	goto error_no_wimax_dev;
	}
	ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_IFIDX]);
	wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
	if (wimax_dev == NULL)
	goto error_no_wimax_dev;
	dev = wimax_dev_to_dev(wimax_dev);

	/* Unpack arguments */
	result = -EINVAL;
	if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
	dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
	"attribute\n");
	goto error_no_data;
	}
	msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
	msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);

	if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
	pipe_name = NULL;
	else {
	struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
	size_t attr_len = nla_len(attr);
	/* libnl-1.1 does not yet support NLA_NUL_STRING */
	result = -ENOMEM;
	pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
	if (pipe_name == NULL)
	goto error_alloc;
	pipe_name[attr_len] = 0;
	}
	mutex_lock(&wimax_dev->mutex);
	result = wimax_dev_is_ready(wimax_dev);
	if (result == -ENOMEDIUM)
	result = 0;
	if (result < 0)
	goto error_not_ready;
	result = -ENOSYS;
	if (wimax_dev->op_msg_from_user == NULL)
	goto error_noop;

	d_printf(1, dev,
	"CRX: nlmsghdr len %u type %u flags 0x%04x seq 0x%x pid %u\n",
	nlh->nlmsg_len, nlh->nlmsg_type, nlh->nlmsg_flags,
	nlh->nlmsg_seq, nlh->nlmsg_pid);
	d_printf(1, dev, "CRX: wimax message %zu bytes\n", msg_len);
	d_dump(2, dev, msg_buf, msg_len);

	result = wimax_dev->op_msg_from_user(wimax_dev, pipe_name,
	msg_buf, msg_len, info);
	error_noop:
	error_not_ready:
	mutex_unlock(&wimax_dev->mutex);
	error_alloc:
	kfree(pipe_name);
	error_no_data:
	dev_put(wimax_dev->net_dev);
	error_no_wimax_dev:
	d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
	return result;
	}