xen: Add xenbus device driver

Access to xenbus is currently handled via xenfs. This adds a device
driver for xenbus and makes xenfs use this code.

Signed-off-by: Bastian Blank <waldi@debian.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

4 files changed, 3 insertions, 596 deletions

diff --git a/drivers/xen/xenfs/Makefile b/drivers/xen/xenfs/Makefile
index 5d45ff13cc01..b019865fcc56 100644
--- a/drivers/xen/xenfs/Makefile
+++ b/drivers/xen/xenfs/Makefile
@@ -1,4 +1,4 @@
 obj-$(CONFIG_XENFS) += xenfs.o
 
-xenfs-y			  = super.o xenbus.o
+xenfs-y			  = super.o
 xenfs-$(CONFIG_XEN_DOM0) += xenstored.o
diff --git a/drivers/xen/xenfs/super.c b/drivers/xen/xenfs/super.c
index a55fbf9a1519..a84b53c01436 100644
--- a/drivers/xen/xenfs/super.c
+++ b/drivers/xen/xenfs/super.c
@@ -17,6 +17,7 @@
 
 #include "xenfs.h"
 #include "../privcmd.h"
+#include "../xenbus/xenbus_comms.h"
 
 #include <asm/xen/hypervisor.h>
 
@@ -83,7 +84,7 @@ static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
 {
 	static struct tree_descr xenfs_files[] = {
 		[1] = {},
-		{ "xenbus", &xenbus_file_ops, S_IRUSR|S_IWUSR },
+		{ "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
 		{ "capabilities", &capabilities_file_ops, S_IRUGO },
 		{ "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
 		{""},
diff --git a/drivers/xen/xenfs/xenbus.c b/drivers/xen/xenfs/xenbus.c
deleted file mode 100644
index bbd000f88af7..000000000000
--- a/drivers/xen/xenfs/xenbus.c
+++ /dev/null
@@ -1,593 +0,0 @@
-/*
- * Driver giving user-space access to the kernel's xenbus connection
- * to xenstore.
- *
- * Copyright (c) 2005, Christian Limpach
- * Copyright (c) 2005, Rusty Russell, IBM Corporation
- *
- * 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; or, when distributed
- * separately from the Linux kernel or incorporated into other
- * software packages, subject to the following license:
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this source file (the "Software"), to deal in the Software without
- * restriction, including without limitation the rights to use, copy, modify,
- * merge, publish, distribute, sublicense, and/or sell copies of the Software,
- * and to permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
- * IN THE SOFTWARE.
- *
- * Changes:
- * 2008-10-07  Alex Zeffertt    Replaced /proc/xen/xenbus with xenfs filesystem
- *                              and /proc/xen compatibility mount point.
- *                              Turned xenfs into a loadable module.
- */
-
-#include <linux/kernel.h>
-#include <linux/errno.h>
-#include <linux/uio.h>
-#include <linux/notifier.h>
-#include <linux/wait.h>
-#include <linux/fs.h>
-#include <linux/poll.h>
-#include <linux/mutex.h>
-#include <linux/sched.h>
-#include <linux/spinlock.h>
-#include <linux/mount.h>
-#include <linux/pagemap.h>
-#include <linux/uaccess.h>
-#include <linux/init.h>
-#include <linux/namei.h>
-#include <linux/string.h>
-#include <linux/slab.h>
-
-#include "xenfs.h"
-#include "../xenbus/xenbus_comms.h"
-
-#include <xen/xenbus.h>
-#include <asm/xen/hypervisor.h>
-
-/*
- * An element of a list of outstanding transactions, for which we're
- * still waiting a reply.
- */
-struct xenbus_transaction_holder {
-	struct list_head list;
-	struct xenbus_transaction handle;
-};
-
-/*
- * A buffer of data on the queue.
- */
-struct read_buffer {
-	struct list_head list;
-	unsigned int cons;
-	unsigned int len;
-	char msg[];
-};
-
-struct xenbus_file_priv {
-	/*
-	 * msgbuffer_mutex is held while partial requests are built up
-	 * and complete requests are acted on.  It therefore protects
-	 * the "transactions" and "watches" lists, and the partial
-	 * request length and buffer.
-	 *
-	 * reply_mutex protects the reply being built up to return to
-	 * usermode.  It nests inside msgbuffer_mutex but may be held
-	 * alone during a watch callback.
-	 */
-	struct mutex msgbuffer_mutex;
-
-	/* In-progress transactions */
-	struct list_head transactions;
-
-	/* Active watches. */
-	struct list_head watches;
-
-	/* Partial request. */
-	unsigned int len;
-	union {
-		struct xsd_sockmsg msg;
-		char buffer[PAGE_SIZE];
-	} u;
-
-	/* Response queue. */
-	struct mutex reply_mutex;
-	struct list_head read_buffers;
-	wait_queue_head_t read_waitq;
-
-};
-
-/* Read out any raw xenbus messages queued up. */
-static ssize_t xenbus_file_read(struct file *filp,
-			       char __user *ubuf,
-			       size_t len, loff_t *ppos)
-{
-	struct xenbus_file_priv *u = filp->private_data;
-	struct read_buffer *rb;
-	unsigned i;
-	int ret;
-
-	mutex_lock(&u->reply_mutex);
-again:
-	while (list_empty(&u->read_buffers)) {
-		mutex_unlock(&u->reply_mutex);
-		if (filp->f_flags & O_NONBLOCK)
-			return -EAGAIN;
-
-		ret = wait_event_interruptible(u->read_waitq,
-					       !list_empty(&u->read_buffers));
-		if (ret)
-			return ret;
-		mutex_lock(&u->reply_mutex);
-	}
-
-	rb = list_entry(u->read_buffers.next, struct read_buffer, list);
-	i = 0;
-	while (i < len) {
-		unsigned sz = min((unsigned)len - i, rb->len - rb->cons);
-
-		ret = copy_to_user(ubuf + i, &rb->msg[rb->cons], sz);
-
-		i += sz - ret;
-		rb->cons += sz - ret;
-
-		if (ret != 0) {
-			if (i == 0)
-				i = -EFAULT;
-			goto out;
-		}
-
-		/* Clear out buffer if it has been consumed */
-		if (rb->cons == rb->len) {
-			list_del(&rb->list);
-			kfree(rb);
-			if (list_empty(&u->read_buffers))
-				break;
-			rb = list_entry(u->read_buffers.next,
-					struct read_buffer, list);
-		}
-	}
-	if (i == 0)
-		goto again;
-
-out:
-	mutex_unlock(&u->reply_mutex);
-	return i;
-}
-
-/*
- * Add a buffer to the queue.  Caller must hold the appropriate lock
- * if the queue is not local.  (Commonly the caller will build up
- * multiple queued buffers on a temporary local list, and then add it
- * to the appropriate list under lock once all the buffers have een
- * successfully allocated.)
- */
-static int queue_reply(struct list_head *queue, const void *data, size_t len)
-{
-	struct read_buffer *rb;
-
-	if (len == 0)
-		return 0;
-
-	rb = kmalloc(sizeof(*rb) + len, GFP_KERNEL);
-	if (rb == NULL)
-		return -ENOMEM;
-
-	rb->cons = 0;
-	rb->len = len;
-
-	memcpy(rb->msg, data, len);
-
-	list_add_tail(&rb->list, queue);
-	return 0;
-}
-
-/*
- * Free all the read_buffer s on a list.
- * Caller must have sole reference to list.
- */
-static void queue_cleanup(struct list_head *list)
-{
-	struct read_buffer *rb;
-
-	while (!list_empty(list)) {
-		rb = list_entry(list->next, struct read_buffer, list);
-		list_del(list->next);
-		kfree(rb);
-	}
-}
-
-struct watch_adapter {
-	struct list_head list;
-	struct xenbus_watch watch;
-	struct xenbus_file_priv *dev_data;
-	char *token;
-};
-
-static void free_watch_adapter(struct watch_adapter *watch)
-{
-	kfree(watch->watch.node);
-	kfree(watch->token);
-	kfree(watch);
-}
-
-static struct watch_adapter *alloc_watch_adapter(const char *path,
-						 const char *token)
-{
-	struct watch_adapter *watch;
-
-	watch = kzalloc(sizeof(*watch), GFP_KERNEL);
-	if (watch == NULL)
-		goto out_fail;
-
-	watch->watch.node = kstrdup(path, GFP_KERNEL);
-	if (watch->watch.node == NULL)
-		goto out_free;
-
-	watch->token = kstrdup(token, GFP_KERNEL);
-	if (watch->token == NULL)
-		goto out_free;
-
-	return watch;
-
-out_free:
-	free_watch_adapter(watch);
-
-out_fail:
-	return NULL;
-}
-
-static void watch_fired(struct xenbus_watch *watch,
-			const char **vec,
-			unsigned int len)
-{
-	struct watch_adapter *adap;
-	struct xsd_sockmsg hdr;
-	const char *path, *token;
-	int path_len, tok_len, body_len, data_len = 0;
-	int ret;
-	LIST_HEAD(staging_q);
-
-	adap = container_of(watch, struct watch_adapter, watch);
-
-	path = vec[XS_WATCH_PATH];
-	token = adap->token;
-
-	path_len = strlen(path) + 1;
-	tok_len = strlen(token) + 1;
-	if (len > 2)
-		data_len = vec[len] - vec[2] + 1;
-	body_len = path_len + tok_len + data_len;
-
-	hdr.type = XS_WATCH_EVENT;
-	hdr.len = body_len;
-
-	mutex_lock(&adap->dev_data->reply_mutex);
-
-	ret = queue_reply(&staging_q, &hdr, sizeof(hdr));
-	if (!ret)
-		ret = queue_reply(&staging_q, path, path_len);
-	if (!ret)
-		ret = queue_reply(&staging_q, token, tok_len);
-	if (!ret && len > 2)
-		ret = queue_reply(&staging_q, vec[2], data_len);
-
-	if (!ret) {
-		/* success: pass reply list onto watcher */
-		list_splice_tail(&staging_q, &adap->dev_data->read_buffers);
-		wake_up(&adap->dev_data->read_waitq);
-	} else
-		queue_cleanup(&staging_q);
-
-	mutex_unlock(&adap->dev_data->reply_mutex);
-}
-
-static int xenbus_write_transaction(unsigned msg_type,
-				    struct xenbus_file_priv *u)
-{
-	int rc;
-	void *reply;
-	struct xenbus_transaction_holder *trans = NULL;
-	LIST_HEAD(staging_q);
-
-	if (msg_type == XS_TRANSACTION_START) {
-		trans = kmalloc(sizeof(*trans), GFP_KERNEL);
-		if (!trans) {
-			rc = -ENOMEM;
-			goto out;
-		}
-	}
-
-	reply = xenbus_dev_request_and_reply(&u->u.msg);
-	if (IS_ERR(reply)) {
-		kfree(trans);
-		rc = PTR_ERR(reply);
-		goto out;
-	}
-
-	if (msg_type == XS_TRANSACTION_START) {
-		trans->handle.id = simple_strtoul(reply, NULL, 0);
-
-		list_add(&trans->list, &u->transactions);
-	} else if (msg_type == XS_TRANSACTION_END) {
-		list_for_each_entry(trans, &u->transactions, list)
-			if (trans->handle.id == u->u.msg.tx_id)
-				break;
-		BUG_ON(&trans->list == &u->transactions);
-		list_del(&trans->list);
-
-		kfree(trans);
-	}
-
-	mutex_lock(&u->reply_mutex);
-	rc = queue_reply(&staging_q, &u->u.msg, sizeof(u->u.msg));
-	if (!rc)
-		rc = queue_reply(&staging_q, reply, u->u.msg.len);
-	if (!rc) {
-		list_splice_tail(&staging_q, &u->read_buffers);
-		wake_up(&u->read_waitq);
-	} else {
-		queue_cleanup(&staging_q);
-	}
-	mutex_unlock(&u->reply_mutex);
-
-	kfree(reply);
-
-out:
-	return rc;
-}
-
-static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u)
-{
-	struct watch_adapter *watch, *tmp_watch;
-	char *path, *token;
-	int err, rc;
-	LIST_HEAD(staging_q);
-
-	path = u->u.buffer + sizeof(u->u.msg);
-	token = memchr(path, 0, u->u.msg.len);
-	if (token == NULL) {
-		rc = -EILSEQ;
-		goto out;
-	}
-	token++;
-
-	if (msg_type == XS_WATCH) {
-		watch = alloc_watch_adapter(path, token);
-		if (watch == NULL) {
-			rc = -ENOMEM;
-			goto out;
-		}
-
-		watch->watch.callback = watch_fired;
-		watch->dev_data = u;
-
-		err = register_xenbus_watch(&watch->watch);
-		if (err) {
-			free_watch_adapter(watch);
-			rc = err;
-			goto out;
-		}
-		list_add(&watch->list, &u->watches);
-	} else {
-		list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) {
-			if (!strcmp(watch->token, token) &&
-			    !strcmp(watch->watch.node, path)) {
-				unregister_xenbus_watch(&watch->watch);
-				list_del(&watch->list);
-				free_watch_adapter(watch);
-				break;
-			}
-		}
-	}
-
-	/* Success.  Synthesize a reply to say all is OK. */
-	{
-		struct {
-			struct xsd_sockmsg hdr;
-			char body[3];
-		} __packed reply = {
-			{
-				.type = msg_type,
-				.len = sizeof(reply.body)
-			},
-			"OK"
-		};
-
-		mutex_lock(&u->reply_mutex);
-		rc = queue_reply(&u->read_buffers, &reply, sizeof(reply));
-		wake_up(&u->read_waitq);
-		mutex_unlock(&u->reply_mutex);
-	}
-
-out:
-	return rc;
-}
-
-static ssize_t xenbus_file_write(struct file *filp,
-				const char __user *ubuf,
-				size_t len, loff_t *ppos)
-{
-	struct xenbus_file_priv *u = filp->private_data;
-	uint32_t msg_type;
-	int rc = len;
-	int ret;
-	LIST_HEAD(staging_q);
-
-	/*
-	 * We're expecting usermode to be writing properly formed
-	 * xenbus messages.  If they write an incomplete message we
-	 * buffer it up.  Once it is complete, we act on it.
-	 */
-
-	/*
-	 * Make sure concurrent writers can't stomp all over each
-	 * other's messages and make a mess of our partial message
-	 * buffer.  We don't make any attemppt to stop multiple
-	 * writers from making a mess of each other's incomplete
-	 * messages; we're just trying to guarantee our own internal
-	 * consistency and make sure that single writes are handled
-	 * atomically.
-	 */
-	mutex_lock(&u->msgbuffer_mutex);
-
-	/* Get this out of the way early to avoid confusion */
-	if (len == 0)
-		goto out;
-
-	/* Can't write a xenbus message larger we can buffer */
-	if ((len + u->len) > sizeof(u->u.buffer)) {
-		/* On error, dump existing buffer */
-		u->len = 0;
-		rc = -EINVAL;
-		goto out;
-	}
-
-	ret = copy_from_user(u->u.buffer + u->len, ubuf, len);
-
-	if (ret != 0) {
-		rc = -EFAULT;
-		goto out;
-	}
-
-	/* Deal with a partial copy. */
-	len -= ret;
-	rc = len;
-
-	u->len += len;
-
-	/* Return if we haven't got a full message yet */
-	if (u->len < sizeof(u->u.msg))
-		goto out;	/* not even the header yet */
-
-	/* If we're expecting a message that's larger than we can
-	   possibly send, dump what we have and return an error. */
-	if ((sizeof(u->u.msg) + u->u.msg.len) > sizeof(u->u.buffer)) {
-		rc = -E2BIG;
-		u->len = 0;
-		goto out;
-	}
-
-	if (u->len < (sizeof(u->u.msg) + u->u.msg.len))
-		goto out;	/* incomplete data portion */
-
-	/*
-	 * OK, now we have a complete message.  Do something with it.
-	 */
-
-	msg_type = u->u.msg.type;
-
-	switch (msg_type) {
-	case XS_WATCH:
-	case XS_UNWATCH:
-		/* (Un)Ask for some path to be watched for changes */
-		ret = xenbus_write_watch(msg_type, u);
-		break;
-
-	default:
-		/* Send out a transaction */
-		ret = xenbus_write_transaction(msg_type, u);
-		break;
-	}
-	if (ret != 0)
-		rc = ret;
-
-	/* Buffered message consumed */
-	u->len = 0;
-
- out:
-	mutex_unlock(&u->msgbuffer_mutex);
-	return rc;
-}
-
-static int xenbus_file_open(struct inode *inode, struct file *filp)
-{
-	struct xenbus_file_priv *u;
-
-	if (xen_store_evtchn == 0)
-		return -ENOENT;
-
-	nonseekable_open(inode, filp);
-
-	u = kzalloc(sizeof(*u), GFP_KERNEL);
-	if (u == NULL)
-		return -ENOMEM;
-
-	INIT_LIST_HEAD(&u->transactions);
-	INIT_LIST_HEAD(&u->watches);
-	INIT_LIST_HEAD(&u->read_buffers);
-	init_waitqueue_head(&u->read_waitq);
-
-	mutex_init(&u->reply_mutex);
-	mutex_init(&u->msgbuffer_mutex);
-
-	filp->private_data = u;
-
-	return 0;
-}
-
-static int xenbus_file_release(struct inode *inode, struct file *filp)
-{
-	struct xenbus_file_priv *u = filp->private_data;
-	struct xenbus_transaction_holder *trans, *tmp;
-	struct watch_adapter *watch, *tmp_watch;
-	struct read_buffer *rb, *tmp_rb;
-
-	/*
-	 * No need for locking here because there are no other users,
-	 * by definition.
-	 */
-
-	list_for_each_entry_safe(trans, tmp, &u->transactions, list) {
-		xenbus_transaction_end(trans->handle, 1);
-		list_del(&trans->list);
-		kfree(trans);
-	}
-
-	list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) {
-		unregister_xenbus_watch(&watch->watch);
-		list_del(&watch->list);
-		free_watch_adapter(watch);
-	}
-
-	list_for_each_entry_safe(rb, tmp_rb, &u->read_buffers, list) {
-		list_del(&rb->list);
-		kfree(rb);
-	}
-	kfree(u);
-
-	return 0;
-}
-
-static unsigned int xenbus_file_poll(struct file *file, poll_table *wait)
-{
-	struct xenbus_file_priv *u = file->private_data;
-
-	poll_wait(file, &u->read_waitq, wait);
-	if (!list_empty(&u->read_buffers))
-		return POLLIN | POLLRDNORM;
-	return 0;
-}
-
-const struct file_operations xenbus_file_ops = {
-	.read = xenbus_file_read,
-	.write = xenbus_file_write,
-	.open = xenbus_file_open,
-	.release = xenbus_file_release,
-	.poll = xenbus_file_poll,
-	.llseek = no_llseek,
-};
diff --git a/drivers/xen/xenfs/xenfs.h b/drivers/xen/xenfs/xenfs.h
index 5056306e7aa8..6b80c7779c02 100644
--- a/drivers/xen/xenfs/xenfs.h
+++ b/drivers/xen/xenfs/xenfs.h
@@ -1,7 +1,6 @@
 #ifndef _XENFS_XENBUS_H
 #define _XENFS_XENBUS_H
 
-extern const struct file_operations xenbus_file_ops;
 extern const struct file_operations xsd_kva_file_ops;
 extern const struct file_operations xsd_port_file_ops;