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[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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