From 2fb3683e7b164ee2b324039f7c9d90fe5b1a259b Mon Sep 17 00:00:00 2001 From: Bastian Blank Date: Sat, 10 Dec 2011 19:29:47 +0100 Subject: 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 Acked-by: Ian Campbell Signed-off-by: Konrad Rzeszutek Wilk --- 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 (limited to 'drivers/xen') diff --git a/drivers/xen/xenbus/Makefile b/drivers/xen/xenbus/Makefile index 8dca685358b4..a2ea363b9f34 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 c21db7513736..6e42800fa499 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 + 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 000000000000..fb30cffe0338 --- /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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "xenbus_comms.h" + +#include +#include + +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 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 @@ -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 -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -#include "xenfs.h" -#include "../xenbus/xenbus_comms.h" - -#include -#include - -/* - * 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; -- cgit v1.2.3