drivers/xen/xenbus/xenbus_dev.c

   1 /*
   2  * xenbus_dev.c
   3  *
   4  * Driver giving user-space access to the kernel's xenbus connection
   5  * to xenstore.
   6  *
   7  * Copyright (c) 2005, Christian Limpach
   8  * Copyright (c) 2005, Rusty Russell, IBM Corporation
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License version 2
  12  * as published by the Free Software Foundation; or, when distributed
  13  * separately from the Linux kernel or incorporated into other
  14  * software packages, subject to the following license:
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a copy
  17  * of this source file (the "Software"), to deal in the Software without
  18  * restriction, including without limitation the rights to use, copy, modify,
  19  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  20  * and to permit persons to whom the Software is furnished to do so, subject to
  21  * the following conditions:
  22  *
  23  * The above copyright notice and this permission notice shall be included in
  24  * all copies or substantial portions of the Software.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  27  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  29  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  30  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  31  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  32  * IN THE SOFTWARE.
  33  */
  34
  35 #include <linux/kernel.h>
  36 #include <linux/errno.h>
  37 #include <linux/uio.h>
  38 #include <linux/notifier.h>
  39 #include <linux/wait.h>
  40 #include <linux/fs.h>
  41 #include <linux/poll.h>
  42
  43 #include "xenbus_comms.h"
  44
  45 #include <asm/uaccess.h>
  46 #include <asm/hypervisor.h>
  47 #include <xen/xenbus.h>
  48 #include <xen/xen_proc.h>
  49 #include <asm/hypervisor.h>
  50
  51 struct xenbus_dev_transaction {
  52         struct list_head list;
  53         struct xenbus_transaction handle;
  54 };
  55
  56 struct xenbus_dev_data {
  57         /* In-progress transaction. */
  58         struct list_head transactions;
  59
  60         /* Active watches. */
  61         struct list_head watches;
  62
  63         /* Partial request. */
  64         unsigned int len;
  65         union {
  66                 struct xsd_sockmsg msg;
  67                 char buffer[PAGE_SIZE];
  68         } u;
  69
  70         /* Response queue. */
  71 #define MASK_READ_IDX(idx) ((idx)&(PAGE_SIZE-1))
  72         char read_buffer[PAGE_SIZE];
  73         unsigned int read_cons, read_prod;
  74         wait_queue_head_t read_waitq;
  75
  76         struct mutex reply_mutex;
  77 };
  78
  79 static struct proc_dir_entry *xenbus_dev_intf;
  80
  81 static ssize_t xenbus_dev_read(struct file *filp,
  82                                char __user *ubuf,
  83                                size_t len, loff_t *ppos)
  84 {
  85         struct xenbus_dev_data *u = filp->private_data;
  86         int i;
  87
  88         if (wait_event_interruptible(u->read_waitq,
  89                                      u->read_prod != u->read_cons))
  90                 return -EINTR;
  91
  92         for (i = 0; i < len; i++) {
  93                 if (u->read_cons == u->read_prod)
  94                         break;
  95                 put_user(u->read_buffer[MASK_READ_IDX(u->read_cons)], ubuf+i);
  96                 u->read_cons++;
  97         }
  98
  99         return i;
 100 }
 101
 102 static void queue_reply(struct xenbus_dev_data *u,
 103                         char *data, unsigned int len)
 104 {
 105         int i;
 106
 107         mutex_lock(&u->reply_mutex);
 108
 109         for (i = 0; i < len; i++, u->read_prod++)
 110                 u->read_buffer[MASK_READ_IDX(u->read_prod)] = data[i];
 111
 112         BUG_ON((u->read_prod - u->read_cons) > sizeof(u->read_buffer));
 113
 114         mutex_unlock(&u->reply_mutex);
 115
 116         wake_up(&u->read_waitq);
 117 }
 118
 119 struct watch_adapter
 120 {
 121         struct list_head list;
 122         struct xenbus_watch watch;
 123         struct xenbus_dev_data *dev_data;
 124         char *token;
 125 };
 126
 127 static void free_watch_adapter (struct watch_adapter *watch)
 128 {
 129         kfree(watch->watch.node);
 130         kfree(watch->token);
 131         kfree(watch);
 132 }
 133
 134 static void watch_fired(struct xenbus_watch *watch,
 135                         const char **vec,
 136                         unsigned int len)
 137 {
 138         struct watch_adapter *adap =
 139             container_of(watch, struct watch_adapter, watch);
 140         struct xsd_sockmsg hdr;
 141         const char *path, *token;
 142         int path_len, tok_len, body_len;
 143
 144         path = vec[XS_WATCH_PATH];
 145         token = adap->token;
 146
 147         path_len = strlen(path) + 1;
 148         tok_len = strlen(token) + 1;
 149         body_len = path_len + tok_len;
 150
 151         hdr.type = XS_WATCH_EVENT;
 152         hdr.len = body_len;
 153
 154         queue_reply(adap->dev_data, (char *)&hdr, sizeof(hdr));
 155         queue_reply(adap->dev_data, (char *)path, path_len);
 156         queue_reply(adap->dev_data, (char *)token, tok_len);
 157 }
 158
 159 static LIST_HEAD(watch_list);
 160
 161 static ssize_t xenbus_dev_write(struct file *filp,
 162                                 const char __user *ubuf,
 163                                 size_t len, loff_t *ppos)
 164 {
 165         struct xenbus_dev_data *u = filp->private_data;
 166         struct xenbus_dev_transaction *trans = NULL;
 167         uint32_t msg_type;
 168         void *reply;
 169         char *path, *token;
 170         struct watch_adapter *watch, *tmp_watch;
 171         int err;
 172
 173         if ((len + u->len) > sizeof(u->u.buffer))
 174                 return -EINVAL;
 175
 176         if (copy_from_user(u->u.buffer + u->len, ubuf, len) != 0)
 177                 return -EFAULT;
 178
 179         u->len += len;
 180         if (u->len < (sizeof(u->u.msg) + u->u.msg.len))
 181                 return len;
 182
 183         msg_type = u->u.msg.type;
 184
 185         switch (msg_type) {
 186         case XS_TRANSACTION_START:
 187         case XS_TRANSACTION_END:
 188         case XS_DIRECTORY:
 189         case XS_READ:
 190         case XS_GET_PERMS:
 191         case XS_RELEASE:
 192         case XS_GET_DOMAIN_PATH:
 193         case XS_WRITE:
 194         case XS_MKDIR:
 195         case XS_RM:
 196         case XS_SET_PERMS:
 197                 if (msg_type == XS_TRANSACTION_START) {
 198                         trans = kmalloc(sizeof(*trans), GFP_KERNEL);
 199                         if (!trans)
 200                                 return -ENOMEM;
 201                 }
 202
 203                 reply = xenbus_dev_request_and_reply(&u->u.msg);
 204                 if (IS_ERR(reply)) {
 205                         kfree(trans);
 206                         return PTR_ERR(reply);
 207                 }
 208
 209                 if (msg_type == XS_TRANSACTION_START) {
 210                         trans->handle.id = simple_strtoul(reply, NULL, 0);
 211                         list_add(&trans->list, &u->transactions);
 212                 } else if (msg_type == XS_TRANSACTION_END) {
 213                         list_for_each_entry(trans, &u->transactions, list)
 214                                 if (trans->handle.id == u->u.msg.tx_id)
 215                                         break;
 216                         BUG_ON(&trans->list == &u->transactions);
 217                         list_del(&trans->list);
 218                         kfree(trans);
 219                 }
 220                 queue_reply(u, (char *)&u->u.msg, sizeof(u->u.msg));
 221                 queue_reply(u, (char *)reply, u->u.msg.len);
 222                 kfree(reply);
 223                 break;
 224
 225         case XS_WATCH:
 226         case XS_UNWATCH:
 227                 path = u->u.buffer + sizeof(u->u.msg);
 228                 token = memchr(path, 0, u->u.msg.len);
 229                 if (token == NULL)
 230                         return -EILSEQ;
 231                 token++;
 232
 233                 if (msg_type == XS_WATCH) {
 234                         static const char * XS_WATCH_RESP = "OK";
 235                         struct xsd_sockmsg hdr;
 236
 237                         watch = kmalloc(sizeof(*watch), GFP_KERNEL);
 238                         watch->watch.node = kmalloc(strlen(path)+1,
 239                                                     GFP_KERNEL);
 240                         strcpy((char *)watch->watch.node, path);
 241                         watch->watch.callback = watch_fired;
 242                         watch->token = kmalloc(strlen(token)+1, GFP_KERNEL);
 243                         strcpy(watch->token, token);
 244                         watch->dev_data = u;
 245
 246                         err = register_xenbus_watch(&watch->watch);
 247                         if (err) {
 248                                 free_watch_adapter(watch);
 249                                 return err;
 250                         }
 251
 252                         list_add(&watch->list, &u->watches);
 253
 254                         hdr.type = XS_WATCH;
 255                         hdr.len = strlen(XS_WATCH_RESP) + 1;
 256                         queue_reply(u, (char *)&hdr, sizeof(hdr));
 257                         queue_reply(u, (char *)XS_WATCH_RESP, hdr.len);
 258                 } else {
 259                         list_for_each_entry_safe(watch, tmp_watch,
 260                                                  &u->watches, list) {
 261                                 if (!strcmp(watch->token, token) &&
 262                                     !strcmp(watch->watch.node, path))
 263                                         break;
 264                                 {
 265                                         unregister_xenbus_watch(&watch->watch);
 266                                         list_del(&watch->list);
 267                                         free_watch_adapter(watch);
 268                                         break;
 269                                 }
 270                         }
 271                 }
 272
 273                 break;
 274
 275         default:
 276                 return -EINVAL;
 277         }
 278
 279         u->len = 0;
 280         return len;
 281 }
 282
 283 static int xenbus_dev_open(struct inode *inode, struct file *filp)
 284 {
 285         struct xenbus_dev_data *u;
 286
 287         if (xen_store_evtchn == 0)
 288                 return -ENOENT;
 289
 290         nonseekable_open(inode, filp);
 291
 292         u = kzalloc(sizeof(*u), GFP_KERNEL);
 293         if (u == NULL)
 294                 return -ENOMEM;
 295
 296         INIT_LIST_HEAD(&u->transactions);
 297         INIT_LIST_HEAD(&u->watches);
 298         init_waitqueue_head(&u->read_waitq);
 299
 300         mutex_init(&u->reply_mutex);
 301
 302         filp->private_data = u;
 303
 304         return 0;
 305 }
 306
 307 static int xenbus_dev_release(struct inode *inode, struct file *filp)
 308 {
 309         struct xenbus_dev_data *u = filp->private_data;
 310         struct xenbus_dev_transaction *trans, *tmp;
 311         struct watch_adapter *watch, *tmp_watch;
 312
 313         list_for_each_entry_safe(trans, tmp, &u->transactions, list) {
 314                 xenbus_transaction_end(trans->handle, 1);
 315                 list_del(&trans->list);
 316                 kfree(trans);
 317         }
 318
 319         list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) {
 320                 unregister_xenbus_watch(&watch->watch);
 321                 list_del(&watch->list);
 322                 free_watch_adapter(watch);
 323         }
 324
 325         kfree(u);
 326
 327         return 0;
 328 }
 329
 330 static unsigned int xenbus_dev_poll(struct file *file, poll_table *wait)
 331 {
 332         struct xenbus_dev_data *u = file->private_data;
 333
 334         poll_wait(file, &u->read_waitq, wait);
 335         if (u->read_cons != u->read_prod)
 336                 return POLLIN | POLLRDNORM;
 337         return 0;
 338 }
 339
 340 static struct file_operations xenbus_dev_file_ops = {
 341         .read = xenbus_dev_read,
 342         .write = xenbus_dev_write,
 343         .open = xenbus_dev_open,
 344         .release = xenbus_dev_release,
 345         .poll = xenbus_dev_poll,
 346 };
 347
 348 int __init
 349 xenbus_dev_init(void)
 350 {
 351         xenbus_dev_intf = create_xen_proc_entry("xenbus", 0400);
 352         if (xenbus_dev_intf)
 353                 xenbus_dev_intf->proc_fops = &xenbus_dev_file_ops;
 354
 355         return 0;
 356 }