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/config.h>
  36 #include <linux/kernel.h>
  37 #include <linux/errno.h>
  38 #include <linux/uio.h>
  39 #include <linux/notifier.h>
  40 #include <linux/wait.h>
  41 #include <linux/fs.h>
  42 #include <linux/poll.h>
  43
  44 #include "xenbus_comms.h"
  45
  46 #include <asm/uaccess.h>
  47 #include <asm/hypervisor.h>
  48 #include <xen/xenbus.h>
  49 #include <xen/xen_proc.h>
  50 #include <asm/hypervisor.h>
  51
  52 struct xenbus_dev_transaction {
  53         struct list_head list;
  54         struct xenbus_transaction handle;
  55 };
  56
  57 struct xenbus_dev_data {
  58         /* In-progress transaction. */
  59         struct list_head transactions;
  60
  61         /* Active watches. */
  62         struct list_head watches;
  63
  64         /* Partial request. */
  65         unsigned int len;
  66         union {
  67                 struct xsd_sockmsg msg;
  68                 char buffer[PAGE_SIZE];
  69         } u;
  70
  71         /* Response queue. */
  72 #define MASK_READ_IDX(idx) ((idx)&(PAGE_SIZE-1))
  73         char read_buffer[PAGE_SIZE];
  74         unsigned int read_cons, read_prod;
  75         wait_queue_head_t read_waitq;
  76
  77         struct mutex reply_mutex;
  78 };
  79
  80 static struct proc_dir_entry *xenbus_dev_intf;
  81
  82 static ssize_t xenbus_dev_read(struct file *filp,
  83                                char __user *ubuf,
  84                                size_t len, loff_t *ppos)
  85 {
  86         struct xenbus_dev_data *u = filp->private_data;
  87         int i;
  88
  89         if (wait_event_interruptible(u->read_waitq,
  90                                      u->read_prod != u->read_cons))
  91                 return -EINTR;
  92
  93         for (i = 0; i < len; i++) {
  94                 if (u->read_cons == u->read_prod)
  95                         break;
  96                 put_user(u->read_buffer[MASK_READ_IDX(u->read_cons)], ubuf+i);
  97                 u->read_cons++;
  98         }
  99
 100         return i;
 101 }
 102
 103 static void queue_reply(struct xenbus_dev_data *u,
 104                         char *data, unsigned int len)
 105 {
 106         int i;
 107
 108         mutex_lock(&u->reply_mutex);
 109
 110         for (i = 0; i < len; i++, u->read_prod++)
 111                 u->read_buffer[MASK_READ_IDX(u->read_prod)] = data[i];
 112
 113         BUG_ON((u->read_prod - u->read_cons) > sizeof(u->read_buffer));
 114
 115         mutex_unlock(&u->reply_mutex);
 116
 117         wake_up(&u->read_waitq);
 118 }
 119
 120 struct watch_adapter
 121 {
 122         struct list_head list;
 123         struct xenbus_watch watch;
 124         struct xenbus_dev_data *dev_data;
 125         char *token;
 126 };
 127
 128 static void free_watch_adapter (struct watch_adapter *watch)
 129 {
 130         kfree(watch->watch.node);
 131         kfree(watch->token);
 132         kfree(watch);
 133 }
 134
 135 static void watch_fired(struct xenbus_watch *watch,
 136                         const char **vec,
 137                         unsigned int len)
 138 {
 139         struct watch_adapter *adap =
 140             container_of(watch, struct watch_adapter, watch);
 141         struct xsd_sockmsg hdr;
 142         const char *path, *token;
 143         int path_len, tok_len, body_len;
 144
 145         path = vec[XS_WATCH_PATH];
 146         token = adap->token;
 147
 148         path_len = strlen(path) + 1;
 149         tok_len = strlen(token) + 1;
 150         body_len = path_len + tok_len;
 151
 152         hdr.type = XS_WATCH_EVENT;
 153         hdr.len = body_len;
 154
 155         queue_reply(adap->dev_data, (char *)&hdr, sizeof(hdr));
 156         queue_reply(adap->dev_data, (char *)path, path_len);
 157         queue_reply(adap->dev_data, (char *)token, tok_len);
 158 }
 159
 160 static LIST_HEAD(watch_list);
 161
 162 static ssize_t xenbus_dev_write(struct file *filp,
 163                                 const char __user *ubuf,
 164                                 size_t len, loff_t *ppos)
 165 {
 166         struct xenbus_dev_data *u = filp->private_data;
 167         struct xenbus_dev_transaction *trans = NULL;
 168         uint32_t msg_type;
 169         void *reply;
 170         char *path, *token;
 171         struct watch_adapter *watch, *tmp_watch;
 172         int err;
 173
 174         if ((len + u->len) > sizeof(u->u.buffer))
 175                 return -EINVAL;
 176
 177         if (copy_from_user(u->u.buffer + u->len, ubuf, len) != 0)
 178                 return -EFAULT;
 179
 180         u->len += len;
 181         if (u->len < (sizeof(u->u.msg) + u->u.msg.len))
 182                 return len;
 183
 184         msg_type = u->u.msg.type;
 185
 186         switch (msg_type) {
 187         case XS_TRANSACTION_START:
 188         case XS_TRANSACTION_END:
 189         case XS_DIRECTORY:
 190         case XS_READ:
 191         case XS_GET_PERMS:
 192         case XS_RELEASE:
 193         case XS_GET_DOMAIN_PATH:
 194         case XS_WRITE:
 195         case XS_MKDIR:
 196         case XS_RM:
 197         case XS_SET_PERMS:
 198                 if (msg_type == XS_TRANSACTION_START) {
 199                         trans = kmalloc(sizeof(*trans), GFP_KERNEL);
 200                         if (!trans)
 201                                 return -ENOMEM;
 202                 }
 203
 204                 reply = xenbus_dev_request_and_reply(&u->u.msg);
 205                 if (IS_ERR(reply)) {
 206                         kfree(trans);
 207                         return PTR_ERR(reply);
 208                 }
 209
 210                 if (msg_type == XS_TRANSACTION_START) {
 211                         trans->handle.id = simple_strtoul(reply, NULL, 0);
 212                         list_add(&trans->list, &u->transactions);
 213                 } else if (msg_type == XS_TRANSACTION_END) {
 214                         list_for_each_entry(trans, &u->transactions, list)
 215                                 if (trans->handle.id == u->u.msg.tx_id)
 216                                         break;
 217                         BUG_ON(&trans->list == &u->transactions);
 218                         list_del(&trans->list);
 219                         kfree(trans);
 220                 }
 221                 queue_reply(u, (char *)&u->u.msg, sizeof(u->u.msg));
 222                 queue_reply(u, (char *)reply, u->u.msg.len);
 223                 kfree(reply);
 224                 break;
 225
 226         case XS_WATCH:
 227         case XS_UNWATCH:
 228                 path = u->u.buffer + sizeof(u->u.msg);
 229                 token = memchr(path, 0, u->u.msg.len);
 230                 if (token == NULL)
 231                         return -EILSEQ;
 232                 token++;
 233
 234                 if (msg_type == XS_WATCH) {
 235                         static const char * XS_WATCH_RESP = "OK";
 236                         struct xsd_sockmsg hdr;
 237
 238                         watch = kmalloc(sizeof(*watch), GFP_KERNEL);
 239                         watch->watch.node = kmalloc(strlen(path)+1,
 240                                                     GFP_KERNEL);
 241                         strcpy((char *)watch->watch.node, path);
 242                         watch->watch.callback = watch_fired;
 243                         watch->token = kmalloc(strlen(token)+1, GFP_KERNEL);
 244                         strcpy(watch->token, token);
 245                         watch->dev_data = u;
 246
 247                         err = register_xenbus_watch(&watch->watch);
 248                         if (err) {
 249                                 free_watch_adapter(watch);
 250                                 return err;
 251                         }
 252
 253                         list_add(&watch->list, &u->watches);
 254
 255                         hdr.type = XS_WATCH;
 256                         hdr.len = strlen(XS_WATCH_RESP) + 1;
 257                         queue_reply(u, (char *)&hdr, sizeof(hdr));
 258                         queue_reply(u, (char *)XS_WATCH_RESP, hdr.len);
 259                 } else {
 260                         list_for_each_entry_safe(watch, tmp_watch,
 261                                                  &u->watches, list) {
 262                                 if (!strcmp(watch->token, token) &&
 263                                     !strcmp(watch->watch.node, path))
 264                                         break;
 265                                 {
 266                                         unregister_xenbus_watch(&watch->watch);
 267                                         list_del(&watch->list);
 268                                         free_watch_adapter(watch);
 269                                         break;
 270                                 }
 271                         }
 272                 }
 273
 274                 break;
 275
 276         default:
 277                 return -EINVAL;
 278         }
 279
 280         u->len = 0;
 281         return len;
 282 }
 283
 284 static int xenbus_dev_open(struct inode *inode, struct file *filp)
 285 {
 286         struct xenbus_dev_data *u;
 287
 288         if (xen_start_info->store_evtchn == 0)
 289                 return -ENOENT;
 290
 291         nonseekable_open(inode, filp);
 292
 293         u = kzalloc(sizeof(*u), GFP_KERNEL);
 294         if (u == NULL)
 295                 return -ENOMEM;
 296
 297         INIT_LIST_HEAD(&u->transactions);
 298         INIT_LIST_HEAD(&u->watches);
 299         init_waitqueue_head(&u->read_waitq);
 300
 301         mutex_init(&u->reply_mutex);
 302
 303         filp->private_data = u;
 304
 305         return 0;
 306 }
 307
 308 static int xenbus_dev_release(struct inode *inode, struct file *filp)
 309 {
 310         struct xenbus_dev_data *u = filp->private_data;
 311         struct xenbus_dev_transaction *trans, *tmp;
 312         struct watch_adapter *watch, *tmp_watch;
 313
 314         list_for_each_entry_safe(trans, tmp, &u->transactions, list) {
 315                 xenbus_transaction_end(trans->handle, 1);
 316                 list_del(&trans->list);
 317                 kfree(trans);
 318         }
 319
 320         list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) {
 321                 unregister_xenbus_watch(&watch->watch);
 322                 list_del(&watch->list);
 323                 free_watch_adapter(watch);
 324         }
 325
 326         kfree(u);
 327
 328         return 0;
 329 }
 330
 331 static unsigned int xenbus_dev_poll(struct file *file, poll_table *wait)
 332 {
 333         struct xenbus_dev_data *u = file->private_data;
 334
 335         poll_wait(file, &u->read_waitq, wait);
 336         if (u->read_cons != u->read_prod)
 337                 return POLLIN | POLLRDNORM;
 338         return 0;
 339 }
 340
 341 static struct file_operations xenbus_dev_file_ops = {
 342         .read = xenbus_dev_read,
 343         .write = xenbus_dev_write,
 344         .open = xenbus_dev_open,
 345         .release = xenbus_dev_release,
 346         .poll = xenbus_dev_poll,
 347 };
 348
 349 static int __init
 350 xenbus_dev_init(void)
 351 {
 352         xenbus_dev_intf = create_xen_proc_entry("xenbus", 0400);
 353         if (xenbus_dev_intf)
 354                 xenbus_dev_intf->proc_fops = &xenbus_dev_file_ops;
 355
 356         return 0;
 357 }
 358
 359 __initcall(xenbus_dev_init);