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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 4/5] 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@xxxxxxxxxx>
---
drivers/xen/xenbus/Makefile | 1 +
drivers/xen/xenbus/xenbus_comms.h | 4 +
drivers/xen/xenbus/xenbus_dev_frontend.c | 624 ++++++++++++++++++++++++++++++
drivers/xen/xenfs/Makefile | 2 +-
drivers/xen/xenfs/super.c | 3 +-
drivers/xen/xenfs/xenbus.c | 593 ----------------------------
drivers/xen/xenfs/xenfs.h | 1 -
7 files changed, 632 insertions(+), 596 deletions(-)
create mode 100644 drivers/xen/xenbus/xenbus_dev_frontend.c
delete mode 100644 drivers/xen/xenfs/xenbus.c
diff --git a/drivers/xen/xenbus/Makefile b/drivers/xen/xenbus/Makefile
index 8dca685..a2ea363 100644
--- a/drivers/xen/xenbus/Makefile
+++ b/drivers/xen/xenbus/Makefile
@@ -1,4 +1,5 @@
obj-y += xenbus.o
+obj-y += xenbus_dev_frontend.o
xenbus-objs =
xenbus-objs += xenbus_client.o
diff --git a/drivers/xen/xenbus/xenbus_comms.h
b/drivers/xen/xenbus/xenbus_comms.h
index c21db75..6e42800 100644
--- a/drivers/xen/xenbus/xenbus_comms.h
+++ b/drivers/xen/xenbus/xenbus_comms.h
@@ -31,6 +31,8 @@
#ifndef _XENBUS_COMMS_H
#define _XENBUS_COMMS_H
+#include <linux/fs.h>
+
int xs_init(void);
int xb_init_comms(void);
@@ -43,4 +45,6 @@ int xs_input_avail(void);
extern struct xenstore_domain_interface *xen_store_interface;
extern int xen_store_evtchn;
+extern const struct file_operations xen_xenbus_fops;
+
#endif /* _XENBUS_COMMS_H */
diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c
b/drivers/xen/xenbus/xenbus_dev_frontend.c
new file mode 100644
index 0000000..fb30cff
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
@@ -0,0 +1,624 @@
+/*
+ * 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 <linux/miscdevice.h>
+#include <linux/module.h>
+
+#include "xenbus_comms.h"
+
+#include <xen/xenbus.h>
+#include <asm/xen/hypervisor.h>
+
+MODULE_LICENSE("GPL");
+
+/*
+ * 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 xen_xenbus_fops = {
+ .read = xenbus_file_read,
+ .write = xenbus_file_write,
+ .open = xenbus_file_open,
+ .release = xenbus_file_release,
+ .poll = xenbus_file_poll,
+ .llseek = no_llseek,
+};
+EXPORT_SYMBOL_GPL(xen_xenbus_fops);
+
+static struct miscdevice xenbus_dev = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "xen/xenbus",
+ .fops = &xen_xenbus_fops,
+};
+
+static int __init xenbus_init(void)
+{
+ int err;
+
+ if (!xen_domain())
+ return -ENODEV;
+
+ err = misc_register(&xenbus_dev);
+ if (err)
+ printk(KERN_ERR "Could not register xenbus device\n");
+ return err;
+}
+
+static void __exit xenbus_exit(void)
+{
+ misc_deregister(&xenbus_dev);
+}
+
+module_init(xenbus_init);
+module_exit(xenbus_exit);
diff --git a/drivers/xen/xenfs/Makefile b/drivers/xen/xenfs/Makefile
index 5d45ff1..b019865 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 a55fbf9..a84b53c 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 bbd000f..0000000
--- 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 5056306..6b80c77 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;
--
1.7.7.3
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