kernel/params.c

   1 /* Helpers for initial module or kernel cmdline parsing
   2    Copyright (C) 2001 Rusty Russell.
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17 */
  18 #include <linux/moduleparam.h>
  19 #include <linux/kernel.h>
  20 #include <linux/string.h>
  21 #include <linux/errno.h>
  22 #include <linux/module.h>
  23 #include <linux/device.h>
  24 #include <linux/err.h>
  25 #include <linux/slab.h>
  26 #include <linux/ctype.h>
  27
  28 #if 0
  29 #define DEBUGP printk
  30 #else
  31 #define DEBUGP(fmt, a...)
  32 #endif
  33
  34 /* Protects all parameters, and incidentally kmalloced_param list. */
  35 static DEFINE_MUTEX(param_lock);
  36
  37 /* This just allows us to keep track of which parameters are kmalloced. */
  38 struct kmalloced_param {
  39         struct list_head list;
  40         char val[];
  41 };
  42 static LIST_HEAD(kmalloced_params);
  43
  44 static void *kmalloc_parameter(unsigned int size)
  45 {
  46         struct kmalloced_param *p;
  47
  48         p = kmalloc(sizeof(*p) + size, GFP_KERNEL);
  49         if (!p)
  50                 return NULL;
  51
  52         list_add(&p->list, &kmalloced_params);
  53         return p->val;
  54 }
  55
  56 /* Does nothing if parameter wasn't kmalloced above. */
  57 static void maybe_kfree_parameter(void *param)
  58 {
  59         struct kmalloced_param *p;
  60
  61         list_for_each_entry(p, &kmalloced_params, list) {
  62                 if (p->val == param) {
  63                         list_del(&p->list);
  64                         kfree(p);
  65                         break;
  66                 }
  67         }
  68 }
  69
  70 static inline char dash2underscore(char c)
  71 {
  72         if (c == '-')
  73                 return '_';
  74         return c;
  75 }
  76
  77 static inline int parameq(const char *input, const char *paramname)
  78 {
  79         unsigned int i;
  80         for (i = 0; dash2underscore(input[i]) == paramname[i]; i++)
  81                 if (input[i] == '\0')
  82                         return 1;
  83         return 0;
  84 }
  85
  86 static int parse_one(char *param,
  87                      char *val,
  88                      const struct kernel_param *params,
  89                      unsigned num_params,
  90                      int (*handle_unknown)(char *param, char *val))
  91 {
  92         unsigned int i;
  93         int err;
  94
  95         /* Find parameter */
  96         for (i = 0; i < num_params; i++) {
  97                 if (parameq(param, params[i].name)) {
  98                         /* Noone handled NULL, so do it here. */
  99                         if (!val && params[i].ops->set != param_set_bool)
 100                                 return -EINVAL;
 101                         DEBUGP("They are equal!  Calling %p\n",
 102                                params[i].ops->set);
 103                         mutex_lock(&param_lock);
 104                         err = params[i].ops->set(val, &params[i]);
 105                         mutex_unlock(&param_lock);
 106                         return err;
 107                 }
 108         }
 109
 110         if (handle_unknown) {
 111                 DEBUGP("Unknown argument: calling %p\n", handle_unknown);
 112                 return handle_unknown(param, val);
 113         }
 114
 115         DEBUGP("Unknown argument `%s'\n", param);
 116         return -ENOENT;
 117 }
 118
 119 /* You can use " around spaces, but can't escape ". */
 120 /* Hyphens and underscores equivalent in parameter names. */
 121 static char *next_arg(char *args, char **param, char **val)
 122 {
 123         unsigned int i, equals = 0;
 124         int in_quote = 0, quoted = 0;
 125         char *next;
 126
 127         if (*args == '"') {
 128                 args++;
 129                 in_quote = 1;
 130                 quoted = 1;
 131         }
 132
 133         for (i = 0; args[i]; i++) {
 134                 if (isspace(args[i]) && !in_quote)
 135                         break;
 136                 if (equals == 0) {
 137                         if (args[i] == '=')
 138                                 equals = i;
 139                 }
 140                 if (args[i] == '"')
 141                         in_quote = !in_quote;
 142         }
 143
 144         *param = args;
 145         if (!equals)
 146                 *val = NULL;
 147         else {
 148                 args[equals] = '\0';
 149                 *val = args + equals + 1;
 150
 151                 /* Don't include quotes in value. */
 152                 if (**val == '"') {
 153                         (*val)++;
 154                         if (args[i-1] == '"')
 155                                 args[i-1] = '\0';
 156                 }
 157                 if (quoted && args[i-1] == '"')
 158                         args[i-1] = '\0';
 159         }
 160
 161         if (args[i]) {
 162                 args[i] = '\0';
 163                 next = args + i + 1;
 164         } else
 165                 next = args + i;
 166
 167         /* Chew up trailing spaces. */
 168         return skip_spaces(next);
 169 }
 170
 171 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */
 172 int parse_args(const char *name,
 173                char *args,
 174                const struct kernel_param *params,
 175                unsigned num,
 176                int (*unknown)(char *param, char *val))
 177 {
 178         char *param, *val;
 179
 180         DEBUGP("Parsing ARGS: %s\n", args);
 181
 182         /* Chew leading spaces */
 183         args = skip_spaces(args);
 184
 185         while (*args) {
 186                 int ret;
 187                 int irq_was_disabled;
 188
 189                 args = next_arg(args, &param, &val);
 190                 irq_was_disabled = irqs_disabled();
 191                 ret = parse_one(param, val, params, num, unknown);
 192                 if (irq_was_disabled && !irqs_disabled()) {
 193                         printk(KERN_WARNING "parse_args(): option '%s' enabled "
 194                                         "irq's!\n", param);
 195                 }
 196                 switch (ret) {
 197                 case -ENOENT:
 198                         printk(KERN_ERR "%s: Unknown parameter `%s'\n",
 199                                name, param);
 200                         return ret;
 201                 case -ENOSPC:
 202                         printk(KERN_ERR
 203                                "%s: `%s' too large for parameter `%s'\n",
 204                                name, val ?: "", param);
 205                         return ret;
 206                 case 0:
 207                         break;
 208                 default:
 209                         printk(KERN_ERR
 210                                "%s: `%s' invalid for parameter `%s'\n",
 211                                name, val ?: "", param);
 212                         return ret;
 213                 }
 214         }
 215
 216         /* All parsed OK. */
 217         return 0;
 218 }
 219
 220 /* Lazy bastard, eh? */
 221 #define STANDARD_PARAM_DEF(name, type, format, tmptype, strtolfn)       \
 222         int param_set_##name(const char *val, const struct kernel_param *kp) \
 223         {                                                               \
 224                 tmptype l;                                              \
 225                 int ret;                                                \
 226                                                                         \
 227                 ret = strtolfn(val, 0, &l);                             \
 228                 if (ret == -EINVAL || ((type)l != l))                   \
 229                         return -EINVAL;                                 \
 230                 *((type *)kp->arg) = l;                                 \
 231                 return 0;                                               \
 232         }                                                               \
 233         int param_get_##name(char *buffer, const struct kernel_param *kp) \
 234         {                                                               \
 235                 return sprintf(buffer, format, *((type *)kp->arg));     \
 236         }                                                               \
 237         struct kernel_param_ops param_ops_##name = {                    \
 238                 .set = param_set_##name,                                \
 239                 .get = param_get_##name,                                \
 240         };                                                              \
 241         EXPORT_SYMBOL(param_set_##name);                                \
 242         EXPORT_SYMBOL(param_get_##name);                                \
 243         EXPORT_SYMBOL(param_ops_##name)
 244
 245
 246 STANDARD_PARAM_DEF(byte, unsigned char, "%c", unsigned long, strict_strtoul);
 247 STANDARD_PARAM_DEF(short, short, "%hi", long, strict_strtol);
 248 STANDARD_PARAM_DEF(ushort, unsigned short, "%hu", unsigned long, strict_strtoul);
 249 STANDARD_PARAM_DEF(int, int, "%i", long, strict_strtol);
 250 STANDARD_PARAM_DEF(uint, unsigned int, "%u", unsigned long, strict_strtoul);
 251 STANDARD_PARAM_DEF(long, long, "%li", long, strict_strtol);
 252 STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", unsigned long, strict_strtoul);
 253
 254 int param_set_charp(const char *val, const struct kernel_param *kp)
 255 {
 256         if (strlen(val) > 1024) {
 257                 printk(KERN_ERR "%s: string parameter too long\n",
 258                        kp->name);
 259                 return -ENOSPC;
 260         }
 261
 262         maybe_kfree_parameter(*(char **)kp->arg);
 263
 264         /* This is a hack.  We can't kmalloc in early boot, and we
 265          * don't need to; this mangled commandline is preserved. */
 266         if (slab_is_available()) {
 267                 *(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
 268                 if (!*(char **)kp->arg)
 269                         return -ENOMEM;
 270                 strcpy(*(char **)kp->arg, val);
 271         } else
 272                 *(const char **)kp->arg = val;
 273
 274         return 0;
 275 }
 276 EXPORT_SYMBOL(param_set_charp);
 277
 278 int param_get_charp(char *buffer, const struct kernel_param *kp)
 279 {
 280         return sprintf(buffer, "%s", *((char **)kp->arg));
 281 }
 282 EXPORT_SYMBOL(param_get_charp);
 283
 284 static void param_free_charp(void *arg)
 285 {
 286         maybe_kfree_parameter(*((char **)arg));
 287 }
 288
 289 struct kernel_param_ops param_ops_charp = {
 290         .set = param_set_charp,
 291         .get = param_get_charp,
 292         .free = param_free_charp,
 293 };
 294 EXPORT_SYMBOL(param_ops_charp);
 295
 296 /* Actually could be a bool or an int, for historical reasons. */
 297 int param_set_bool(const char *val, const struct kernel_param *kp)
 298 {
 299         bool v;
 300
 301         /* No equals means "set"... */
 302         if (!val) val = "1";
 303
 304         /* One of =[yYnN01] */
 305         switch (val[0]) {
 306         case 'y': case 'Y': case '1':
 307                 v = true;
 308                 break;
 309         case 'n': case 'N': case '0':
 310                 v = false;
 311                 break;
 312         default:
 313                 return -EINVAL;
 314         }
 315
 316         if (kp->flags & KPARAM_ISBOOL)
 317                 *(bool *)kp->arg = v;
 318         else
 319                 *(int *)kp->arg = v;
 320         return 0;
 321 }
 322 EXPORT_SYMBOL(param_set_bool);
 323
 324 int param_get_bool(char *buffer, const struct kernel_param *kp)
 325 {
 326         bool val;
 327         if (kp->flags & KPARAM_ISBOOL)
 328                 val = *(bool *)kp->arg;
 329         else
 330                 val = *(int *)kp->arg;
 331
 332         /* Y and N chosen as being relatively non-coder friendly */
 333         return sprintf(buffer, "%c", val ? 'Y' : 'N');
 334 }
 335 EXPORT_SYMBOL(param_get_bool);
 336
 337 struct kernel_param_ops param_ops_bool = {
 338         .set = param_set_bool,
 339         .get = param_get_bool,
 340 };
 341 EXPORT_SYMBOL(param_ops_bool);
 342
 343 /* This one must be bool. */
 344 int param_set_invbool(const char *val, const struct kernel_param *kp)
 345 {
 346         int ret;
 347         bool boolval;
 348         struct kernel_param dummy;
 349
 350         dummy.arg = &boolval;
 351         dummy.flags = KPARAM_ISBOOL;
 352         ret = param_set_bool(val, &dummy);
 353         if (ret == 0)
 354                 *(bool *)kp->arg = !boolval;
 355         return ret;
 356 }
 357 EXPORT_SYMBOL(param_set_invbool);
 358
 359 int param_get_invbool(char *buffer, const struct kernel_param *kp)
 360 {
 361         return sprintf(buffer, "%c", (*(bool *)kp->arg) ? 'N' : 'Y');
 362 }
 363 EXPORT_SYMBOL(param_get_invbool);
 364
 365 struct kernel_param_ops param_ops_invbool = {
 366         .set = param_set_invbool,
 367         .get = param_get_invbool,
 368 };
 369 EXPORT_SYMBOL(param_ops_invbool);
 370
 371 /* We break the rule and mangle the string. */
 372 static int param_array(const char *name,
 373                        const char *val,
 374                        unsigned int min, unsigned int max,
 375                        void *elem, int elemsize,
 376                        int (*set)(const char *, const struct kernel_param *kp),
 377                        u16 flags,
 378                        unsigned int *num)
 379 {
 380         int ret;
 381         struct kernel_param kp;
 382         char save;
 383
 384         /* Get the name right for errors. */
 385         kp.name = name;
 386         kp.arg = elem;
 387         kp.flags = flags;
 388
 389         *num = 0;
 390         /* We expect a comma-separated list of values. */
 391         do {
 392                 int len;
 393
 394                 if (*num == max) {
 395                         printk(KERN_ERR "%s: can only take %i arguments\n",
 396                                name, max);
 397                         return -EINVAL;
 398                 }
 399                 len = strcspn(val, ",");
 400
 401                 /* nul-terminate and parse */
 402                 save = val[len];
 403                 ((char *)val)[len] = '\0';
 404                 BUG_ON(!mutex_is_locked(&param_lock));
 405                 ret = set(val, &kp);
 406
 407                 if (ret != 0)
 408                         return ret;
 409                 kp.arg += elemsize;
 410                 val += len+1;
 411                 (*num)++;
 412         } while (save == ',');
 413
 414         if (*num < min) {
 415                 printk(KERN_ERR "%s: needs at least %i arguments\n",
 416                        name, min);
 417                 return -EINVAL;
 418         }
 419         return 0;
 420 }
 421
 422 static int param_array_set(const char *val, const struct kernel_param *kp)
 423 {
 424         const struct kparam_array *arr = kp->arr;
 425         unsigned int temp_num;
 426
 427         return param_array(kp->name, val, 1, arr->max, arr->elem,
 428                            arr->elemsize, arr->ops->set, kp->flags,
 429                            arr->num ?: &temp_num);
 430 }
 431
 432 static int param_array_get(char *buffer, const struct kernel_param *kp)
 433 {
 434         int i, off, ret;
 435         const struct kparam_array *arr = kp->arr;
 436         struct kernel_param p;
 437
 438         p = *kp;
 439         for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
 440                 if (i)
 441                         buffer[off++] = ',';
 442                 p.arg = arr->elem + arr->elemsize * i;
 443                 BUG_ON(!mutex_is_locked(&param_lock));
 444                 ret = arr->ops->get(buffer + off, &p);
 445                 if (ret < 0)
 446                         return ret;
 447                 off += ret;
 448         }
 449         buffer[off] = '\0';
 450         return off;
 451 }
 452
 453 static void param_array_free(void *arg)
 454 {
 455         unsigned int i;
 456         const struct kparam_array *arr = arg;
 457
 458         if (arr->ops->free)
 459                 for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
 460                         arr->ops->free(arr->elem + arr->elemsize * i);
 461 }
 462
 463 struct kernel_param_ops param_array_ops = {
 464         .set = param_array_set,
 465         .get = param_array_get,
 466         .free = param_array_free,
 467 };
 468 EXPORT_SYMBOL(param_array_ops);
 469
 470 int param_set_copystring(const char *val, const struct kernel_param *kp)
 471 {
 472         const struct kparam_string *kps = kp->str;
 473
 474         if (strlen(val)+1 > kps->maxlen) {
 475                 printk(KERN_ERR "%s: string doesn't fit in %u chars.\n",
 476                        kp->name, kps->maxlen-1);
 477                 return -ENOSPC;
 478         }
 479         strcpy(kps->string, val);
 480         return 0;
 481 }
 482 EXPORT_SYMBOL(param_set_copystring);
 483
 484 int param_get_string(char *buffer, const struct kernel_param *kp)
 485 {
 486         const struct kparam_string *kps = kp->str;
 487         return strlcpy(buffer, kps->string, kps->maxlen);
 488 }
 489 EXPORT_SYMBOL(param_get_string);
 490
 491 struct kernel_param_ops param_ops_string = {
 492         .set = param_set_copystring,
 493         .get = param_get_string,
 494 };
 495 EXPORT_SYMBOL(param_ops_string);
 496
 497 /* sysfs output in /sys/modules/XYZ/parameters/ */
 498 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
 499 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
 500
 501 extern struct kernel_param __start___param[], __stop___param[];
 502
 503 struct param_attribute
 504 {
 505         struct module_attribute mattr;
 506         const struct kernel_param *param;
 507 };
 508
 509 struct module_param_attrs
 510 {
 511         unsigned int num;
 512         struct attribute_group grp;
 513         struct param_attribute attrs[0];
 514 };
 515
 516 #ifdef CONFIG_SYSFS
 517 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
 518
 519 static ssize_t param_attr_show(struct module_attribute *mattr,
 520                                struct module *mod, char *buf)
 521 {
 522         int count;
 523         struct param_attribute *attribute = to_param_attr(mattr);
 524
 525         if (!attribute->param->ops->get)
 526                 return -EPERM;
 527
 528         mutex_lock(&param_lock);
 529         count = attribute->param->ops->get(buf, attribute->param);
 530         mutex_unlock(&param_lock);
 531         if (count > 0) {
 532                 strcat(buf, "\n");
 533                 ++count;
 534         }
 535         return count;
 536 }
 537
 538 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
 539 static ssize_t param_attr_store(struct module_attribute *mattr,
 540                                 struct module *owner,
 541                                 const char *buf, size_t len)
 542 {
 543         int err;
 544         struct param_attribute *attribute = to_param_attr(mattr);
 545
 546         if (!attribute->param->ops->set)
 547                 return -EPERM;
 548
 549         mutex_lock(&param_lock);
 550         err = attribute->param->ops->set(buf, attribute->param);
 551         mutex_unlock(&param_lock);
 552         if (!err)
 553                 return len;
 554         return err;
 555 }
 556 #endif
 557
 558 #ifdef CONFIG_MODULES
 559 #define __modinit
 560 #else
 561 #define __modinit __init
 562 #endif
 563
 564 #ifdef CONFIG_SYSFS
 565 void __kernel_param_lock(void)
 566 {
 567         mutex_lock(&param_lock);
 568 }
 569 EXPORT_SYMBOL(__kernel_param_lock);
 570
 571 void __kernel_param_unlock(void)
 572 {
 573         mutex_unlock(&param_lock);
 574 }
 575 EXPORT_SYMBOL(__kernel_param_unlock);
 576
 577 /*
 578  * add_sysfs_param - add a parameter to sysfs
 579  * @mk: struct module_kobject
 580  * @kparam: the actual parameter definition to add to sysfs
 581  * @name: name of parameter
 582  *
 583  * Create a kobject if for a (per-module) parameter if mp NULL, and
 584  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
 585  * if there's an error.
 586  */
 587 static __modinit int add_sysfs_param(struct module_kobject *mk,
 588                                      const struct kernel_param *kp,
 589                                      const char *name)
 590 {
 591         struct module_param_attrs *new;
 592         struct attribute **attrs;
 593         int err, num;
 594
 595         /* We don't bother calling this with invisible parameters. */
 596         BUG_ON(!kp->perm);
 597
 598         if (!mk->mp) {
 599                 num = 0;
 600                 attrs = NULL;
 601         } else {
 602                 num = mk->mp->num;
 603                 attrs = mk->mp->grp.attrs;
 604         }
 605
 606         /* Enlarge. */
 607         new = krealloc(mk->mp,
 608                        sizeof(*mk->mp) + sizeof(mk->mp->attrs[0]) * (num+1),
 609                        GFP_KERNEL);
 610         if (!new) {
 611                 kfree(mk->mp);
 612                 err = -ENOMEM;
 613                 goto fail;
 614         }
 615         attrs = krealloc(attrs, sizeof(new->grp.attrs[0])*(num+2), GFP_KERNEL);
 616         if (!attrs) {
 617                 err = -ENOMEM;
 618                 goto fail_free_new;
 619         }
 620
 621         /* Sysfs wants everything zeroed. */
 622         memset(new, 0, sizeof(*new));
 623         memset(&new->attrs[num], 0, sizeof(new->attrs[num]));
 624         memset(&attrs[num], 0, sizeof(attrs[num]));
 625         new->grp.name = "parameters";
 626         new->grp.attrs = attrs;
 627
 628         /* Tack new one on the end. */
 629         sysfs_attr_init(&new->attrs[num].mattr.attr);
 630         new->attrs[num].param = kp;
 631         new->attrs[num].mattr.show = param_attr_show;
 632         new->attrs[num].mattr.store = param_attr_store;
 633         new->attrs[num].mattr.attr.name = (char *)name;
 634         new->attrs[num].mattr.attr.mode = kp->perm;
 635         new->num = num+1;
 636
 637         /* Fix up all the pointers, since krealloc can move us */
 638         for (num = 0; num < new->num; num++)
 639                 new->grp.attrs[num] = &new->attrs[num].mattr.attr;
 640         new->grp.attrs[num] = NULL;
 641
 642         mk->mp = new;
 643         return 0;
 644
 645 fail_free_new:
 646         kfree(new);
 647 fail:
 648         mk->mp = NULL;
 649         return err;
 650 }
 651
 652 #ifdef CONFIG_MODULES
 653 static void free_module_param_attrs(struct module_kobject *mk)
 654 {
 655         kfree(mk->mp->grp.attrs);
 656         kfree(mk->mp);
 657         mk->mp = NULL;
 658 }
 659
 660 /*
 661  * module_param_sysfs_setup - setup sysfs support for one module
 662  * @mod: module
 663  * @kparam: module parameters (array)
 664  * @num_params: number of module parameters
 665  *
 666  * Adds sysfs entries for module parameters under
 667  * /sys/module/[mod->name]/parameters/
 668  */
 669 int module_param_sysfs_setup(struct module *mod,
 670                              const struct kernel_param *kparam,
 671                              unsigned int num_params)
 672 {
 673         int i, err;
 674         bool params = false;
 675
 676         for (i = 0; i < num_params; i++) {
 677                 if (kparam[i].perm == 0)
 678                         continue;
 679                 err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
 680                 if (err)
 681                         return err;
 682                 params = true;
 683         }
 684
 685         if (!params)
 686                 return 0;
 687
 688         /* Create the param group. */
 689         err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 690         if (err)
 691                 free_module_param_attrs(&mod->mkobj);
 692         return err;
 693 }
 694
 695 /*
 696  * module_param_sysfs_remove - remove sysfs support for one module
 697  * @mod: module
 698  *
 699  * Remove sysfs entries for module parameters and the corresponding
 700  * kobject.
 701  */
 702 void module_param_sysfs_remove(struct module *mod)
 703 {
 704         if (mod->mkobj.mp) {
 705                 sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 706                 /* We are positive that no one is using any param
 707                  * attrs at this point.  Deallocate immediately. */
 708                 free_module_param_attrs(&mod->mkobj);
 709         }
 710 }
 711 #endif
 712
 713 void destroy_params(const struct kernel_param *params, unsigned num)
 714 {
 715         unsigned int i;
 716
 717         for (i = 0; i < num; i++)
 718                 if (params[i].ops->free)
 719                         params[i].ops->free(params[i].arg);
 720 }
 721
 722 static void __init kernel_add_sysfs_param(const char *name,
 723                                           struct kernel_param *kparam,
 724                                           unsigned int name_skip)
 725 {
 726         struct module_kobject *mk;
 727         struct kobject *kobj;
 728         int err;
 729
 730         kobj = kset_find_obj(module_kset, name);
 731         if (kobj) {
 732                 /* We already have one.  Remove params so we can add more. */
 733                 mk = to_module_kobject(kobj);
 734                 /* We need to remove it before adding parameters. */
 735                 sysfs_remove_group(&mk->kobj, &mk->mp->grp);
 736         } else {
 737                 mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
 738                 BUG_ON(!mk);
 739
 740                 mk->mod = THIS_MODULE;
 741                 mk->kobj.kset = module_kset;
 742                 err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
 743                                            "%s", name);
 744                 if (err) {
 745                         kobject_put(&mk->kobj);
 746                         printk(KERN_ERR "Module '%s' failed add to sysfs, "
 747                                "error number %d\n", name, err);
 748                         printk(KERN_ERR "The system will be unstable now.\n");
 749                         return;
 750                 }
 751                 /* So that exit path is even. */
 752                 kobject_get(&mk->kobj);
 753         }
 754
 755         /* These should not fail at boot. */
 756         err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
 757         BUG_ON(err);
 758         err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
 759         BUG_ON(err);
 760         kobject_uevent(&mk->kobj, KOBJ_ADD);
 761         kobject_put(&mk->kobj);
 762 }
 763
 764 /*
 765  * param_sysfs_builtin - add contents in /sys/parameters for built-in modules
 766  *
 767  * Add module_parameters to sysfs for "modules" built into the kernel.
 768  *
 769  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
 770  * "parameter" name is stored behind a dot in kernel_param->name. So,
 771  * extract the "module" name for all built-in kernel_param-eters,
 772  * and for all who have the same, call kernel_add_sysfs_param.
 773  */
 774 static void __init param_sysfs_builtin(void)
 775 {
 776         struct kernel_param *kp;
 777         unsigned int name_len;
 778         char modname[MODULE_NAME_LEN];
 779
 780         for (kp = __start___param; kp < __stop___param; kp++) {
 781                 char *dot;
 782
 783                 if (kp->perm == 0)
 784                         continue;
 785
 786                 dot = strchr(kp->name, '.');
 787                 if (!dot) {
 788                         /* This happens for core_param() */
 789                         strcpy(modname, "kernel");
 790                         name_len = 0;
 791                 } else {
 792                         name_len = dot - kp->name + 1;
 793                         strlcpy(modname, kp->name, name_len);
 794                 }
 795                 kernel_add_sysfs_param(modname, kp, name_len);
 796         }
 797 }
 798
 799
 800 /* module-related sysfs stuff */
 801
 802 static ssize_t module_attr_show(struct kobject *kobj,
 803                                 struct attribute *attr,
 804                                 char *buf)
 805 {
 806         struct module_attribute *attribute;
 807         struct module_kobject *mk;
 808         int ret;
 809
 810         attribute = to_module_attr(attr);
 811         mk = to_module_kobject(kobj);
 812
 813         if (!attribute->show)
 814                 return -EIO;
 815
 816         ret = attribute->show(attribute, mk->mod, buf);
 817
 818         return ret;
 819 }
 820
 821 static ssize_t module_attr_store(struct kobject *kobj,
 822                                 struct attribute *attr,
 823                                 const char *buf, size_t len)
 824 {
 825         struct module_attribute *attribute;
 826         struct module_kobject *mk;
 827         int ret;
 828
 829         attribute = to_module_attr(attr);
 830         mk = to_module_kobject(kobj);
 831
 832         if (!attribute->store)
 833                 return -EIO;
 834
 835         ret = attribute->store(attribute, mk->mod, buf, len);
 836
 837         return ret;
 838 }
 839
 840 static const struct sysfs_ops module_sysfs_ops = {
 841         .show = module_attr_show,
 842         .store = module_attr_store,
 843 };
 844
 845 static int uevent_filter(struct kset *kset, struct kobject *kobj)
 846 {
 847         struct kobj_type *ktype = get_ktype(kobj);
 848
 849         if (ktype == &module_ktype)
 850                 return 1;
 851         return 0;
 852 }
 853
 854 static const struct kset_uevent_ops module_uevent_ops = {
 855         .filter = uevent_filter,
 856 };
 857
 858 struct kset *module_kset;
 859 int module_sysfs_initialized;
 860
 861 struct kobj_type module_ktype = {
 862         .sysfs_ops =    &module_sysfs_ops,
 863 };
 864
 865 /*
 866  * param_sysfs_init - wrapper for built-in params support
 867  */
 868 static int __init param_sysfs_init(void)
 869 {
 870         module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
 871         if (!module_kset) {
 872                 printk(KERN_WARNING "%s (%d): error creating kset\n",
 873                         __FILE__, __LINE__);
 874                 return -ENOMEM;
 875         }
 876         module_sysfs_initialized = 1;
 877
 878         param_sysfs_builtin();
 879
 880         return 0;
 881 }
 882 subsys_initcall(param_sysfs_init);
 883
 884 #endif /* CONFIG_SYSFS */