xen-vtx-unstable

annotate linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_xs.c @ 5876:69beaae8a1fa

Clean up xenbus code not to use priorities.
Signed-off-by: Rusty Russel <rusty@rustcorp.com.au>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
author cl349@firebug.cl.cam.ac.uk
date Tue Jul 26 17:38:33 2005 +0000 (2005-07-26)
parents 5f0446907501
children 2333f6616d18
rev   line source
cl349@5598 1 /******************************************************************************
cl349@5598 2 * xenbus_xs.c
cl349@5598 3 *
cl349@5598 4 * This is the kernel equivalent of the "xs" library. We don't need everything
cl349@5863 5 * and we use xenbus_comms for communication.
cl349@5598 6 *
cl349@5598 7 * Copyright (C) 2005 Rusty Russell, IBM Corporation
cl349@5598 8 *
cl349@5598 9 * This file may be distributed separately from the Linux kernel, or
cl349@5598 10 * incorporated into other software packages, subject to the following license:
cl349@5598 11 *
cl349@5598 12 * Permission is hereby granted, free of charge, to any person obtaining a copy
cl349@5598 13 * of this source file (the "Software"), to deal in the Software without
cl349@5598 14 * restriction, including without limitation the rights to use, copy, modify,
cl349@5598 15 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
cl349@5598 16 * and to permit persons to whom the Software is furnished to do so, subject to
cl349@5598 17 * the following conditions:
cl349@5598 18 *
cl349@5598 19 * The above copyright notice and this permission notice shall be included in
cl349@5598 20 * all copies or substantial portions of the Software.
cl349@5598 21 *
cl349@5598 22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
cl349@5598 23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
cl349@5598 24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
cl349@5598 25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
cl349@5598 26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
cl349@5598 27 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
cl349@5598 28 * IN THE SOFTWARE.
cl349@5598 29 */
cl349@5598 30
cl349@5598 31 #include <linux/errno.h>
cl349@5598 32 #include <linux/types.h>
cl349@5598 33 #include "xenstore/xenstored.h"
cl349@5598 34 #include <linux/uio.h>
cl349@5598 35 #include <linux/kernel.h>
cl349@5598 36 #include <linux/string.h>
cl349@5598 37 #include <linux/err.h>
cl349@5598 38 #include <linux/slab.h>
cl349@5598 39 #include <linux/fcntl.h>
cl349@5598 40 #include <linux/kthread.h>
cl349@5598 41 #include <asm-xen/xenbus.h>
cl349@5598 42 #include "xenbus_comms.h"
cl349@5598 43
cl349@5598 44 #define streq(a, b) (strcmp((a), (b)) == 0)
cl349@5598 45
cl349@5874 46 static char printf_buffer[4096];
cl349@5598 47 static void *xs_in, *xs_out;
cl349@5598 48 static LIST_HEAD(watches);
cl349@5863 49 DECLARE_MUTEX(xenbus_lock);
cl349@5598 50
cl349@5598 51 static int get_error(const char *errorstring)
cl349@5598 52 {
cl349@5598 53 unsigned int i;
cl349@5598 54
cl349@5598 55 for (i = 0; !streq(errorstring, xsd_errors[i].errstring); i++) {
cl349@5598 56 if (i == ARRAY_SIZE(xsd_errors) - 1) {
cl349@5670 57 printk(KERN_WARNING
cl349@5670 58 "XENBUS xen store gave: unknown error %s",
cl349@5598 59 errorstring);
cl349@5598 60 return EINVAL;
cl349@5598 61 }
cl349@5598 62 }
cl349@5598 63 return xsd_errors[i].errnum;
cl349@5598 64 }
cl349@5598 65
cl349@5598 66 static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len)
cl349@5598 67 {
cl349@5598 68 struct xsd_sockmsg msg;
cl349@5598 69 void *ret;
cl349@5598 70 int err;
cl349@5598 71
cl349@5598 72 err = xb_read(xs_in, &msg, sizeof(msg));
cl349@5598 73 if (err)
cl349@5598 74 return ERR_PTR(err);
cl349@5598 75
cl349@5598 76 ret = kmalloc(msg.len + 1, GFP_KERNEL);
cl349@5598 77 if (!ret)
cl349@5598 78 return ERR_PTR(-ENOMEM);
cl349@5598 79
cl349@5598 80 err = xb_read(xs_in, ret, msg.len);
cl349@5598 81 if (err) {
cl349@5598 82 kfree(ret);
cl349@5598 83 return ERR_PTR(err);
cl349@5598 84 }
cl349@5598 85 ((char*)ret)[msg.len] = '\0';
cl349@5598 86
cl349@5598 87 *type = msg.type;
cl349@5598 88 if (len)
cl349@5598 89 *len = msg.len;
cl349@5598 90 return ret;
cl349@5598 91 }
cl349@5598 92
cl349@5747 93 /* Emergency write. */
cl349@5863 94 void xenbus_debug_write(const char *str, unsigned int count)
cl349@5747 95 {
cl349@5747 96 struct xsd_sockmsg msg;
cl349@5747 97 void *out = (void *)xen_start_info.store_page;
cl349@5747 98
cl349@5747 99 msg.type = XS_DEBUG;
cl349@5747 100 msg.len = sizeof("print") + count + 1;
cl349@5747 101
cl349@5747 102 xb_write(out, &msg, sizeof(msg));
cl349@5747 103 xb_write(out, "print", sizeof("print"));
cl349@5747 104 xb_write(out, str, count);
cl349@5747 105 xb_write(out, "", 1);
cl349@5747 106 }
cl349@5747 107
cl349@5598 108 /* Send message to xs, get kmalloc'ed reply. ERR_PTR() on error. */
cl349@5598 109 static void *xs_talkv(enum xsd_sockmsg_type type,
cl349@5598 110 const struct kvec *iovec,
cl349@5598 111 unsigned int num_vecs,
cl349@5598 112 unsigned int *len)
cl349@5598 113 {
cl349@5598 114 struct xsd_sockmsg msg;
cl349@5598 115 void *ret = NULL;
cl349@5598 116 unsigned int i;
cl349@5598 117 int err;
cl349@5598 118
cl349@5863 119 WARN_ON(down_trylock(&xenbus_lock) == 0);
cl349@5598 120
cl349@5598 121 msg.type = type;
cl349@5598 122 msg.len = 0;
cl349@5598 123 for (i = 0; i < num_vecs; i++)
cl349@5598 124 msg.len += iovec[i].iov_len;
cl349@5598 125
cl349@5598 126 err = xb_write(xs_out, &msg, sizeof(msg));
cl349@5598 127 if (err)
cl349@5598 128 return ERR_PTR(err);
cl349@5598 129
cl349@5598 130 for (i = 0; i < num_vecs; i++) {
cl349@5598 131 err = xb_write(xs_out, iovec[i].iov_base, iovec[i].iov_len);;
cl349@5598 132 if (err)
cl349@5598 133 return ERR_PTR(err);
cl349@5598 134 }
cl349@5598 135
cl349@5598 136 /* Watches can have fired before reply comes: daemon detects
cl349@5598 137 * and re-transmits, so we can ignore this. */
cl349@5598 138 do {
cl349@5598 139 kfree(ret);
cl349@5598 140 ret = read_reply(&msg.type, len);
cl349@5598 141 if (IS_ERR(ret))
cl349@5598 142 return ret;
cl349@5598 143 } while (msg.type == XS_WATCH_EVENT);
cl349@5598 144
cl349@5598 145 if (msg.type == XS_ERROR) {
cl349@5598 146 err = get_error(ret);
cl349@5598 147 kfree(ret);
cl349@5598 148 return ERR_PTR(-err);
cl349@5598 149 }
cl349@5598 150
cl349@5598 151 BUG_ON(msg.type != type);
cl349@5598 152 return ret;
cl349@5598 153 }
cl349@5598 154
cl349@5598 155 /* Simplified version of xs_talkv: single message. */
cl349@5598 156 static void *xs_single(enum xsd_sockmsg_type type,
cl349@5598 157 const char *string, unsigned int *len)
cl349@5598 158 {
cl349@5598 159 struct kvec iovec;
cl349@5598 160
cl349@5598 161 iovec.iov_base = (void *)string;
cl349@5598 162 iovec.iov_len = strlen(string) + 1;
cl349@5598 163 return xs_talkv(type, &iovec, 1, len);
cl349@5598 164 }
cl349@5598 165
cl349@5598 166 /* Many commands only need an ack, don't care what it says. */
cl349@5598 167 static int xs_error(char *reply)
cl349@5598 168 {
cl349@5598 169 if (IS_ERR(reply))
cl349@5598 170 return PTR_ERR(reply);
cl349@5598 171 kfree(reply);
cl349@5598 172 return 0;
cl349@5598 173 }
cl349@5598 174
cl349@5598 175 static unsigned int count_strings(const char *strings, unsigned int len)
cl349@5598 176 {
cl349@5598 177 unsigned int num;
cl349@5598 178 const char *p;
cl349@5598 179
cl349@5598 180 for (p = strings, num = 0; p < strings + len; p += strlen(p) + 1)
cl349@5598 181 num++;
cl349@5598 182
cl349@5598 183 return num;
cl349@5598 184 }
cl349@5598 185
cl349@5863 186 /* Return the path to dir with /name appended. */
cl349@5863 187 static char *join(const char *dir, const char *name)
cl349@5863 188 {
cl349@5863 189 static char buffer[4096];
cl349@5863 190
cl349@5863 191 BUG_ON(down_trylock(&xenbus_lock) == 0);
cl349@5863 192 BUG_ON(strlen(dir) + strlen("/") + strlen(name) + 1 > sizeof(buffer));
cl349@5863 193
cl349@5863 194 strcpy(buffer, dir);
cl349@5863 195 if (!streq(name, "")) {
cl349@5863 196 strcat(buffer, "/");
cl349@5863 197 strcat(buffer, name);
cl349@5863 198 }
cl349@5863 199 return buffer;
cl349@5863 200 }
cl349@5863 201
cl349@5863 202 char **xenbus_directory(const char *dir, const char *node, unsigned int *num)
cl349@5598 203 {
cl349@5598 204 char *strings, *p, **ret;
cl349@5598 205 unsigned int len;
cl349@5598 206
cl349@5863 207 strings = xs_single(XS_DIRECTORY, join(dir, node), &len);
cl349@5598 208 if (IS_ERR(strings))
cl349@5598 209 return (char **)strings;
cl349@5598 210
cl349@5598 211 /* Count the strings. */
cl349@5598 212 *num = count_strings(strings, len);
cl349@5598 213
cl349@5598 214 /* Transfer to one big alloc for easy freeing. */
cl349@5598 215 ret = kmalloc(*num * sizeof(char *) + len, GFP_ATOMIC);
cl349@5598 216 if (!ret) {
cl349@5598 217 kfree(strings);
cl349@5598 218 return ERR_PTR(-ENOMEM);
cl349@5598 219 }
cl349@5598 220 memcpy(&ret[*num], strings, len);
cl349@5598 221 kfree(strings);
cl349@5598 222
cl349@5598 223 strings = (char *)&ret[*num];
cl349@5598 224 for (p = strings, *num = 0; p < strings + len; p += strlen(p) + 1)
cl349@5598 225 ret[(*num)++] = p;
cl349@5598 226 return ret;
cl349@5598 227 }
cl349@5598 228
cl349@5598 229 /* Check if a path exists. Return 1 if it does. */
cl349@5863 230 int xenbus_exists(const char *dir, const char *node)
cl349@5598 231 {
cl349@5863 232 char **d;
cl349@5670 233 int dir_n;
cl349@5598 234
cl349@5867 235 d = xenbus_directory(dir, node, &dir_n);
cl349@5863 236 if (IS_ERR(d))
cl349@5670 237 return 0;
cl349@5863 238 kfree(d);
cl349@5670 239 return 1;
cl349@5598 240 }
cl349@5598 241
cl349@5598 242 /* Get the value of a single file.
cl349@5598 243 * Returns a kmalloced value: call free() on it after use.
cl349@5598 244 * len indicates length in bytes.
cl349@5598 245 */
cl349@5863 246 void *xenbus_read(const char *dir, const char *node, unsigned int *len)
cl349@5598 247 {
cl349@5863 248 return xs_single(XS_READ, join(dir, node), len);
cl349@5598 249 }
cl349@5598 250
cl349@5598 251 /* Write the value of a single file.
cl349@5598 252 * Returns -err on failure. createflags can be 0, O_CREAT, or O_CREAT|O_EXCL.
cl349@5598 253 */
cl349@5863 254 int xenbus_write(const char *dir, const char *node,
cl349@5863 255 const char *string, int createflags)
cl349@5598 256 {
cl349@5863 257 const char *flags, *path;
cl349@5598 258 struct kvec iovec[3];
cl349@5598 259
cl349@5863 260 path = join(dir, node);
cl349@5598 261 /* Format: Flags (as string), path, data. */
cl349@5598 262 if (createflags == 0)
cl349@5598 263 flags = XS_WRITE_NONE;
cl349@5598 264 else if (createflags == O_CREAT)
cl349@5598 265 flags = XS_WRITE_CREATE;
cl349@5598 266 else if (createflags == (O_CREAT|O_EXCL))
cl349@5598 267 flags = XS_WRITE_CREATE_EXCL;
cl349@5598 268 else
cl349@5598 269 return -EINVAL;
cl349@5598 270
cl349@5598 271 iovec[0].iov_base = (void *)path;
cl349@5598 272 iovec[0].iov_len = strlen(path) + 1;
cl349@5598 273 iovec[1].iov_base = (void *)flags;
cl349@5598 274 iovec[1].iov_len = strlen(flags) + 1;
cl349@5863 275 iovec[2].iov_base = (void *)string;
cl349@5863 276 iovec[2].iov_len = strlen(string);
cl349@5598 277
cl349@5598 278 return xs_error(xs_talkv(XS_WRITE, iovec, ARRAY_SIZE(iovec), NULL));
cl349@5598 279 }
cl349@5598 280
cl349@5598 281 /* Create a new directory. */
cl349@5863 282 int xenbus_mkdir(const char *dir, const char *node)
cl349@5598 283 {
cl349@5863 284 return xs_error(xs_single(XS_MKDIR, join(dir, node), NULL));
cl349@5598 285 }
cl349@5598 286
cl349@5598 287 /* Destroy a file or directory (directories must be empty). */
cl349@5863 288 int xenbus_rm(const char *dir, const char *node)
cl349@5598 289 {
cl349@5863 290 return xs_error(xs_single(XS_RM, join(dir, node), NULL));
cl349@5598 291 }
cl349@5598 292
cl349@5598 293 /* Start a transaction: changes by others will not be seen during this
cl349@5598 294 * transaction, and changes will not be visible to others until end.
cl349@5598 295 * Transaction only applies to the given subtree.
cl349@5598 296 * You can only have one transaction at any time.
cl349@5598 297 */
cl349@5863 298 int xenbus_transaction_start(const char *subtree)
cl349@5598 299 {
cl349@5598 300 return xs_error(xs_single(XS_TRANSACTION_START, subtree, NULL));
cl349@5598 301 }
cl349@5598 302
cl349@5598 303 /* End a transaction.
cl349@5598 304 * If abandon is true, transaction is discarded instead of committed.
cl349@5598 305 */
cl349@5863 306 int xenbus_transaction_end(int abort)
cl349@5598 307 {
cl349@5598 308 char abortstr[2];
cl349@5598 309
cl349@5598 310 if (abort)
cl349@5598 311 strcpy(abortstr, "F");
cl349@5598 312 else
cl349@5598 313 strcpy(abortstr, "T");
cl349@5598 314 return xs_error(xs_single(XS_TRANSACTION_END, abortstr, NULL));
cl349@5598 315 }
cl349@5598 316
cl349@5863 317 /* Single read and scanf: returns -errno or num scanned. */
cl349@5863 318 int xenbus_scanf(const char *dir, const char *node, const char *fmt, ...)
cl349@5863 319 {
cl349@5863 320 va_list ap;
cl349@5863 321 int ret;
cl349@5863 322 char *val;
cl349@5863 323
cl349@5863 324 val = xenbus_read(dir, node, NULL);
cl349@5863 325 if (IS_ERR(val))
cl349@5863 326 return PTR_ERR(val);
cl349@5863 327
cl349@5863 328 va_start(ap, fmt);
cl349@5863 329 ret = vsscanf(val, fmt, ap);
cl349@5863 330 va_end(ap);
cl349@5863 331 kfree(val);
cl349@5863 332 /* Distinctive errno. */
cl349@5863 333 if (ret == 0)
cl349@5863 334 return -ERANGE;
cl349@5863 335 return ret;
cl349@5863 336 }
cl349@5863 337
cl349@5863 338 /* Single printf and write: returns -errno or 0. */
cl349@5863 339 int xenbus_printf(const char *dir, const char *node, const char *fmt, ...)
cl349@5598 340 {
cl349@5863 341 va_list ap;
cl349@5863 342 int ret;
cl349@5863 343
cl349@5863 344 BUG_ON(down_trylock(&xenbus_lock) == 0);
cl349@5863 345 va_start(ap, fmt);
cl349@5874 346 ret = vsnprintf(printf_buffer, sizeof(printf_buffer), fmt, ap);
cl349@5863 347 va_end(ap);
cl349@5863 348
cl349@5874 349 BUG_ON(ret > sizeof(printf_buffer)-1);
cl349@5874 350 return xenbus_write(dir, node, printf_buffer, O_CREAT);
cl349@5863 351 }
cl349@5598 352
cl349@5874 353 /* Report a (negative) errno into the store, with explanation. */
cl349@5874 354 void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...)
cl349@5874 355 {
cl349@5874 356 va_list ap;
cl349@5874 357 int ret;
cl349@5874 358 unsigned int len;
cl349@5874 359
cl349@5874 360 BUG_ON(down_trylock(&xenbus_lock) == 0);
cl349@5874 361
cl349@5874 362 len = sprintf(printf_buffer, "%i ", -err);
cl349@5874 363 va_start(ap, fmt);
cl349@5874 364 ret = vsnprintf(printf_buffer+len, sizeof(printf_buffer)-len, fmt, ap);
cl349@5874 365 va_end(ap);
cl349@5874 366
cl349@5874 367 BUG_ON(len + ret > sizeof(printf_buffer)-1);
cl349@5874 368 dev->has_error = 1;
cl349@5874 369 if (xenbus_write(dev->nodename, "error", printf_buffer, O_CREAT) != 0)
cl349@5874 370 printk("xenbus: failed to write error node for %s (%s)\n",
cl349@5874 371 dev->nodename, printf_buffer);
cl349@5874 372 }
cl349@5874 373
cl349@5874 374 /* Clear any error. */
cl349@5874 375 void xenbus_dev_ok(struct xenbus_device *dev)
cl349@5874 376 {
cl349@5874 377 if (dev->has_error) {
cl349@5874 378 if (xenbus_rm(dev->nodename, "error") != 0)
cl349@5874 379 printk("xenbus: failed to clear error node for %s\n",
cl349@5874 380 dev->nodename);
cl349@5874 381 else
cl349@5874 382 dev->has_error = 0;
cl349@5874 383 }
cl349@5874 384 }
cl349@5874 385
cl349@5863 386 /* Takes tuples of names, scanf-style args, and void **, NULL terminated. */
cl349@5863 387 int xenbus_gather(const char *dir, ...)
cl349@5863 388 {
cl349@5863 389 va_list ap;
cl349@5863 390 const char *name;
cl349@5863 391 int ret = 0;
cl349@5863 392
cl349@5863 393 va_start(ap, dir);
cl349@5863 394 while (ret == 0 && (name = va_arg(ap, char *)) != NULL) {
cl349@5863 395 const char *fmt = va_arg(ap, char *);
cl349@5863 396 void *result = va_arg(ap, void *);
cl349@5863 397 char *p;
cl349@5863 398
cl349@5863 399 p = xenbus_read(dir, name, NULL);
cl349@5863 400 if (IS_ERR(p)) {
cl349@5863 401 ret = PTR_ERR(p);
cl349@5863 402 break;
cl349@5863 403 }
cl349@5863 404 if (sscanf(p, fmt, result) == 0)
cl349@5863 405 ret = -EINVAL;
cl349@5863 406 kfree(p);
cl349@5863 407 }
cl349@5863 408 va_end(ap);
cl349@5863 409 return ret;
cl349@5598 410 }
cl349@5598 411
cl349@5876 412 static int xs_watch(const char *path, const char *token)
cl349@5598 413 {
cl349@5876 414 struct kvec iov[2];
cl349@5598 415
cl349@5598 416 iov[0].iov_base = (void *)path;
cl349@5598 417 iov[0].iov_len = strlen(path) + 1;
cl349@5598 418 iov[1].iov_base = (void *)token;
cl349@5598 419 iov[1].iov_len = strlen(token) + 1;
cl349@5598 420
cl349@5598 421 return xs_error(xs_talkv(XS_WATCH, iov, ARRAY_SIZE(iov), NULL));
cl349@5598 422 }
cl349@5598 423
cl349@5598 424 static char *xs_read_watch(char **token)
cl349@5598 425 {
cl349@5598 426 enum xsd_sockmsg_type type;
cl349@5598 427 char *ret;
cl349@5598 428
cl349@5598 429 ret = read_reply(&type, NULL);
cl349@5598 430 if (IS_ERR(ret))
cl349@5598 431 return ret;
cl349@5598 432
cl349@5598 433 BUG_ON(type != XS_WATCH_EVENT);
cl349@5598 434 *token = ret + strlen(ret) + 1;
cl349@5598 435 return ret;
cl349@5598 436 }
cl349@5598 437
cl349@5598 438 static int xs_acknowledge_watch(const char *token)
cl349@5598 439 {
cl349@5598 440 return xs_error(xs_single(XS_WATCH_ACK, token, NULL));
cl349@5598 441 }
cl349@5598 442
cl349@5598 443 static int xs_unwatch(const char *path, const char *token)
cl349@5598 444 {
cl349@5598 445 struct kvec iov[2];
cl349@5598 446
cl349@5598 447 iov[0].iov_base = (char *)path;
cl349@5598 448 iov[0].iov_len = strlen(path) + 1;
cl349@5598 449 iov[1].iov_base = (char *)token;
cl349@5598 450 iov[1].iov_len = strlen(token) + 1;
cl349@5598 451
cl349@5598 452 return xs_error(xs_talkv(XS_UNWATCH, iov, ARRAY_SIZE(iov), NULL));
cl349@5598 453 }
cl349@5598 454
cl349@5598 455 /* A little paranoia: we don't just trust token. */
cl349@5598 456 static struct xenbus_watch *find_watch(const char *token)
cl349@5598 457 {
cl349@5598 458 struct xenbus_watch *i, *cmp;
cl349@5598 459
cl349@5598 460 cmp = (void *)simple_strtoul(token, NULL, 16);
cl349@5598 461
cl349@5598 462 list_for_each_entry(i, &watches, list)
cl349@5598 463 if (i == cmp)
cl349@5598 464 return i;
cl349@5598 465 return NULL;
cl349@5598 466 }
cl349@5598 467
cl349@5598 468 /* Register callback to watch this node. */
cl349@5598 469 int register_xenbus_watch(struct xenbus_watch *watch)
cl349@5598 470 {
cl349@5598 471 /* Pointer in ascii is the token. */
cl349@5598 472 char token[sizeof(watch) * 2 + 1];
cl349@5598 473 int err;
cl349@5598 474
cl349@5598 475 sprintf(token, "%lX", (long)watch);
cl349@5598 476 BUG_ON(find_watch(token));
cl349@5598 477
cl349@5876 478 err = xs_watch(watch->node, token);
cl349@5598 479 if (!err)
cl349@5598 480 list_add(&watch->list, &watches);
cl349@5598 481 return err;
cl349@5598 482 }
cl349@5598 483
cl349@5875 484 static struct xenbus_watch *watch_callback;
cl349@5875 485
cl349@5598 486 void unregister_xenbus_watch(struct xenbus_watch *watch)
cl349@5598 487 {
cl349@5598 488 char token[sizeof(watch) * 2 + 1];
cl349@5598 489 int err;
cl349@5598 490
cl349@5598 491 sprintf(token, "%lX", (long)watch);
cl349@5598 492 BUG_ON(!find_watch(token));
cl349@5598 493
cl349@5598 494 err = xs_unwatch(watch->node, token);
cl349@5598 495 list_del(&watch->list);
cl349@5598 496
cl349@5875 497 /* Make sure watch thread knows we unwatched, so don't ack. */
cl349@5875 498 if (watch_callback == watch)
cl349@5875 499 watch_callback = NULL;
cl349@5875 500
cl349@5598 501 if (err)
cl349@5598 502 printk(KERN_WARNING "XENBUS Failed to release watch %s: %i\n",
cl349@5598 503 watch->node, err);
cl349@5598 504 }
cl349@5598 505
cl349@5598 506 static int watch_thread(void *unused)
cl349@5598 507 {
cl349@5598 508 for (;;) {
cl349@5598 509 char *token;
cl349@5598 510 char *node = NULL;
cl349@5598 511
cl349@5598 512 wait_event(xb_waitq, xs_input_avail(xs_in));
cl349@5598 513
cl349@5598 514 /* If this is a spurious wakeup caused by someone
cl349@5598 515 * doing an op, they'll hold the lock and the buffer
cl349@5598 516 * will be empty by the time we get there.
cl349@5598 517 */
cl349@5863 518 down(&xenbus_lock);
cl349@5598 519 if (xs_input_avail(xs_in))
cl349@5598 520 node = xs_read_watch(&token);
cl349@5747 521
cl349@5598 522 if (node && !IS_ERR(node)) {
cl349@5598 523 struct xenbus_watch *w;
cl349@5598 524 int err;
cl349@5598 525
cl349@5598 526 w = find_watch(token);
cl349@5598 527 BUG_ON(!w);
cl349@5875 528 watch_callback = w;
cl349@5598 529 w->callback(w, node);
cl349@5875 530
cl349@5875 531 if (watch_callback) {
cl349@5875 532 err = xs_acknowledge_watch(token);
cl349@5875 533 if (err)
cl349@5875 534 printk(KERN_WARNING
cl349@5875 535 "XENBUS ack %s fail %i\n",
cl349@5875 536 node, err);
cl349@5875 537 }
cl349@5598 538 kfree(node);
cl349@5598 539 } else
cl349@5598 540 printk(KERN_WARNING "XENBUS xs_read_watch: %li\n",
cl349@5598 541 PTR_ERR(node));
cl349@5863 542 up(&xenbus_lock);
cl349@5598 543 }
cl349@5598 544 }
cl349@5598 545
cl349@5598 546 int xs_init(void)
cl349@5598 547 {
cl349@5598 548 int err;
cl349@5598 549 struct task_struct *watcher;
cl349@5598 550
cl349@5598 551 err = xb_init_comms(&xs_in, &xs_out);
cl349@5598 552 if (err)
cl349@5598 553 return err;
cl349@5598 554
cl349@5598 555 watcher = kthread_run(watch_thread, NULL, "kxbwatch");
cl349@5598 556 if (IS_ERR(watcher))
cl349@5598 557 return PTR_ERR(watcher);
cl349@5598 558 return 0;
cl349@5598 559 }