lib/dynamic_debug.c

   1 /*
   2  * lib/dynamic_debug.c
   3  *
   4  * make pr_debug()/dev_dbg() calls runtime configurable based upon their
   5  * source module.
   6  *
   7  * Copyright (C) 2008 Jason Baron <jbaron@redhat.com>
   8  * By Greg Banks <gnb@melbourne.sgi.com>
   9  * Copyright (c) 2008 Silicon Graphics Inc.  All Rights Reserved.
  10  * Copyright (C) 2011 Bart Van Assche.  All Rights Reserved.
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
  14
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/kallsyms.h>
  19 #include <linux/version.h>
  20 #include <linux/types.h>
  21 #include <linux/mutex.h>
  22 #include <linux/proc_fs.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/list.h>
  25 #include <linux/sysctl.h>
  26 #include <linux/ctype.h>
  27 #include <linux/string.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/dynamic_debug.h>
  30 #include <linux/debugfs.h>
  31 #include <linux/slab.h>
  32 #include <linux/jump_label.h>
  33 #include <linux/hardirq.h>
  34 #include <linux/sched.h>
  35 #include <linux/device.h>
  36 #include <linux/netdevice.h>
  37
  38 extern struct _ddebug __start___verbose[];
  39 extern struct _ddebug __stop___verbose[];
  40
  41 struct ddebug_table {
  42         struct list_head link;
  43         char *mod_name;
  44         unsigned int num_ddebugs;
  45         unsigned int num_enabled;
  46         struct _ddebug *ddebugs;
  47 };
  48
  49 struct ddebug_query {
  50         const char *filename;
  51         const char *module;
  52         const char *function;
  53         const char *format;
  54         unsigned int first_lineno, last_lineno;
  55 };
  56
  57 struct ddebug_iter {
  58         struct ddebug_table *table;
  59         unsigned int idx;
  60 };
  61
  62 static DEFINE_MUTEX(ddebug_lock);
  63 static LIST_HEAD(ddebug_tables);
  64 static int verbose = 0;
  65
  66 /* Return the last part of a pathname */
  67 static inline const char *basename(const char *path)
  68 {
  69         const char *tail = strrchr(path, '/');
  70         return tail ? tail+1 : path;
  71 }
  72
  73 static struct { unsigned flag:8; char opt_char; } opt_array[] = {
  74         { _DPRINTK_FLAGS_PRINT, 'p' },
  75         { _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
  76         { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
  77         { _DPRINTK_FLAGS_INCL_LINENO, 'l' },
  78         { _DPRINTK_FLAGS_INCL_TID, 't' },
  79 };
  80
  81 /* format a string into buf[] which describes the _ddebug's flags */
  82 static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
  83                                     size_t maxlen)
  84 {
  85         char *p = buf;
  86         int i;
  87
  88         BUG_ON(maxlen < 4);
  89         for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
  90                 if (dp->flags & opt_array[i].flag)
  91                         *p++ = opt_array[i].opt_char;
  92         if (p == buf)
  93                 *p++ = '-';
  94         *p = '\0';
  95
  96         return buf;
  97 }
  98
  99 /*
 100  * Search the tables for _ddebug's which match the given
 101  * `query' and apply the `flags' and `mask' to them.  Tells
 102  * the user which ddebug's were changed, or whether none
 103  * were matched.
 104  */
 105 static void ddebug_change(const struct ddebug_query *query,
 106                            unsigned int flags, unsigned int mask)
 107 {
 108         int i;
 109         struct ddebug_table *dt;
 110         unsigned int newflags;
 111         unsigned int nfound = 0;
 112         char flagbuf[8];
 113
 114         /* search for matching ddebugs */
 115         mutex_lock(&ddebug_lock);
 116         list_for_each_entry(dt, &ddebug_tables, link) {
 117
 118                 /* match against the module name */
 119                 if (query->module != NULL &&
 120                     strcmp(query->module, dt->mod_name))
 121                         continue;
 122
 123                 for (i = 0 ; i < dt->num_ddebugs ; i++) {
 124                         struct _ddebug *dp = &dt->ddebugs[i];
 125
 126                         /* match against the source filename */
 127                         if (query->filename != NULL &&
 128                             strcmp(query->filename, dp->filename) &&
 129                             strcmp(query->filename, basename(dp->filename)))
 130                                 continue;
 131
 132                         /* match against the function */
 133                         if (query->function != NULL &&
 134                             strcmp(query->function, dp->function))
 135                                 continue;
 136
 137                         /* match against the format */
 138                         if (query->format != NULL &&
 139                             strstr(dp->format, query->format) == NULL)
 140                                 continue;
 141
 142                         /* match against the line number range */
 143                         if (query->first_lineno &&
 144                             dp->lineno < query->first_lineno)
 145                                 continue;
 146                         if (query->last_lineno &&
 147                             dp->lineno > query->last_lineno)
 148                                 continue;
 149
 150                         nfound++;
 151
 152                         newflags = (dp->flags & mask) | flags;
 153                         if (newflags == dp->flags)
 154                                 continue;
 155
 156                         if (!newflags)
 157                                 dt->num_enabled--;
 158                         else if (!dp->flags)
 159                                 dt->num_enabled++;
 160                         dp->flags = newflags;
 161                         if (newflags)
 162                                 dp->enabled = 1;
 163                         else
 164                                 dp->enabled = 0;
 165                         if (verbose)
 166                                 pr_info("changed %s:%d [%s]%s %s\n",
 167                                         dp->filename, dp->lineno,
 168                                         dt->mod_name, dp->function,
 169                                         ddebug_describe_flags(dp, flagbuf,
 170                                                         sizeof(flagbuf)));
 171                 }
 172         }
 173         mutex_unlock(&ddebug_lock);
 174
 175         if (!nfound && verbose)
 176                 pr_info("no matches for query\n");
 177 }
 178
 179 /*
 180  * Split the buffer `buf' into space-separated words.
 181  * Handles simple " and ' quoting, i.e. without nested,
 182  * embedded or escaped \".  Return the number of words
 183  * or <0 on error.
 184  */
 185 static int ddebug_tokenize(char *buf, char *words[], int maxwords)
 186 {
 187         int nwords = 0;
 188
 189         while (*buf) {
 190                 char *end;
 191
 192                 /* Skip leading whitespace */
 193                 buf = skip_spaces(buf);
 194                 if (!*buf)
 195                         break;  /* oh, it was trailing whitespace */
 196
 197                 /* Run `end' over a word, either whitespace separated or quoted */
 198                 if (*buf == '"' || *buf == '\'') {
 199                         int quote = *buf++;
 200                         for (end = buf ; *end && *end != quote ; end++)
 201                                 ;
 202                         if (!*end)
 203                                 return -EINVAL; /* unclosed quote */
 204                 } else {
 205                         for (end = buf ; *end && !isspace(*end) ; end++)
 206                                 ;
 207                         BUG_ON(end == buf);
 208                 }
 209                 /* Here `buf' is the start of the word, `end' is one past the end */
 210
 211                 if (nwords == maxwords)
 212                         return -EINVAL; /* ran out of words[] before bytes */
 213                 if (*end)
 214                         *end++ = '\0';  /* terminate the word */
 215                 words[nwords++] = buf;
 216                 buf = end;
 217         }
 218
 219         if (verbose) {
 220                 int i;
 221                 pr_info("split into words:");
 222                 for (i = 0 ; i < nwords ; i++)
 223                         pr_cont(" \"%s\"", words[i]);
 224                 pr_cont("\n");
 225         }
 226
 227         return nwords;
 228 }
 229
 230 /*
 231  * Parse a single line number.  Note that the empty string ""
 232  * is treated as a special case and converted to zero, which
 233  * is later treated as a "don't care" value.
 234  */
 235 static inline int parse_lineno(const char *str, unsigned int *val)
 236 {
 237         char *end = NULL;
 238         BUG_ON(str == NULL);
 239         if (*str == '\0') {
 240                 *val = 0;
 241                 return 0;
 242         }
 243         *val = simple_strtoul(str, &end, 10);
 244         return end == NULL || end == str || *end != '\0' ? -EINVAL : 0;
 245 }
 246
 247 /*
 248  * Undo octal escaping in a string, inplace.  This is useful to
 249  * allow the user to express a query which matches a format
 250  * containing embedded spaces.
 251  */
 252 #define isodigit(c)             ((c) >= '0' && (c) <= '7')
 253 static char *unescape(char *str)
 254 {
 255         char *in = str;
 256         char *out = str;
 257
 258         while (*in) {
 259                 if (*in == '\\') {
 260                         if (in[1] == '\\') {
 261                                 *out++ = '\\';
 262                                 in += 2;
 263                                 continue;
 264                         } else if (in[1] == 't') {
 265                                 *out++ = '\t';
 266                                 in += 2;
 267                                 continue;
 268                         } else if (in[1] == 'n') {
 269                                 *out++ = '\n';
 270                                 in += 2;
 271                                 continue;
 272                         } else if (isodigit(in[1]) &&
 273                                  isodigit(in[2]) &&
 274                                  isodigit(in[3])) {
 275                                 *out++ = ((in[1] - '0')<<6) |
 276                                           ((in[2] - '0')<<3) |
 277                                           (in[3] - '0');
 278                                 in += 4;
 279                                 continue;
 280                         }
 281                 }
 282                 *out++ = *in++;
 283         }
 284         *out = '\0';
 285
 286         return str;
 287 }
 288
 289 /*
 290  * Parse words[] as a ddebug query specification, which is a series
 291  * of (keyword, value) pairs chosen from these possibilities:
 292  *
 293  * func <function-name>
 294  * file <full-pathname>
 295  * file <base-filename>
 296  * module <module-name>
 297  * format <escaped-string-to-find-in-format>
 298  * line <lineno>
 299  * line <first-lineno>-<last-lineno> // where either may be empty
 300  */
 301 static int ddebug_parse_query(char *words[], int nwords,
 302                                struct ddebug_query *query)
 303 {
 304         unsigned int i;
 305
 306         /* check we have an even number of words */
 307         if (nwords % 2 != 0)
 308                 return -EINVAL;
 309         memset(query, 0, sizeof(*query));
 310
 311         for (i = 0 ; i < nwords ; i += 2) {
 312                 if (!strcmp(words[i], "func"))
 313                         query->function = words[i+1];
 314                 else if (!strcmp(words[i], "file"))
 315                         query->filename = words[i+1];
 316                 else if (!strcmp(words[i], "module"))
 317                         query->module = words[i+1];
 318                 else if (!strcmp(words[i], "format"))
 319                         query->format = unescape(words[i+1]);
 320                 else if (!strcmp(words[i], "line")) {
 321                         char *first = words[i+1];
 322                         char *last = strchr(first, '-');
 323                         if (last)
 324                                 *last++ = '\0';
 325                         if (parse_lineno(first, &query->first_lineno) < 0)
 326                                 return -EINVAL;
 327                         if (last != NULL) {
 328                                 /* range <first>-<last> */
 329                                 if (parse_lineno(last, &query->last_lineno) < 0)
 330                                         return -EINVAL;
 331                         } else {
 332                                 query->last_lineno = query->first_lineno;
 333                         }
 334                 } else {
 335                         if (verbose)
 336                                 pr_err("unknown keyword \"%s\"\n", words[i]);
 337                         return -EINVAL;
 338                 }
 339         }
 340
 341         if (verbose)
 342                 pr_info("q->function=\"%s\" q->filename=\"%s\" "
 343                         "q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u\n",
 344                         query->function, query->filename,
 345                         query->module, query->format, query->first_lineno,
 346                         query->last_lineno);
 347
 348         return 0;
 349 }
 350
 351 /*
 352  * Parse `str' as a flags specification, format [-+=][p]+.
 353  * Sets up *maskp and *flagsp to be used when changing the
 354  * flags fields of matched _ddebug's.  Returns 0 on success
 355  * or <0 on error.
 356  */
 357 static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
 358                                unsigned int *maskp)
 359 {
 360         unsigned flags = 0;
 361         int op = '=', i;
 362
 363         switch (*str) {
 364         case '+':
 365         case '-':
 366         case '=':
 367                 op = *str++;
 368                 break;
 369         default:
 370                 return -EINVAL;
 371         }
 372         if (verbose)
 373                 pr_info("op='%c'\n", op);
 374
 375         for ( ; *str ; ++str) {
 376                 for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
 377                         if (*str == opt_array[i].opt_char) {
 378                                 flags |= opt_array[i].flag;
 379                                 break;
 380                         }
 381                 }
 382                 if (i < 0)
 383                         return -EINVAL;
 384         }
 385         if (flags == 0)
 386                 return -EINVAL;
 387         if (verbose)
 388                 pr_info("flags=0x%x\n", flags);
 389
 390         /* calculate final *flagsp, *maskp according to mask and op */
 391         switch (op) {
 392         case '=':
 393                 *maskp = 0;
 394                 *flagsp = flags;
 395                 break;
 396         case '+':
 397                 *maskp = ~0U;
 398                 *flagsp = flags;
 399                 break;
 400         case '-':
 401                 *maskp = ~flags;
 402                 *flagsp = 0;
 403                 break;
 404         }
 405         if (verbose)
 406                 pr_info("*flagsp=0x%x *maskp=0x%x\n", *flagsp, *maskp);
 407         return 0;
 408 }
 409
 410 static int ddebug_exec_query(char *query_string)
 411 {
 412         unsigned int flags = 0, mask = 0;
 413         struct ddebug_query query;
 414 #define MAXWORDS 9
 415         int nwords;
 416         char *words[MAXWORDS];
 417
 418         nwords = ddebug_tokenize(query_string, words, MAXWORDS);
 419         if (nwords <= 0)
 420                 return -EINVAL;
 421         if (ddebug_parse_query(words, nwords-1, &query))
 422                 return -EINVAL;
 423         if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
 424                 return -EINVAL;
 425
 426         /* actually go and implement the change */
 427         ddebug_change(&query, flags, mask);
 428         return 0;
 429 }
 430
 431 static int dynamic_emit_prefix(const struct _ddebug *descriptor)
 432 {
 433         char tid[sizeof(int) + sizeof(int)/2 + 4];
 434         char lineno[sizeof(int) + sizeof(int)/2];
 435
 436         if (descriptor->flags & _DPRINTK_FLAGS_INCL_TID) {
 437                 if (in_interrupt())
 438                         snprintf(tid, sizeof(tid), "%s", "<intr> ");
 439                 else
 440                         snprintf(tid, sizeof(tid), "[%d] ",
 441                                  task_pid_vnr(current));
 442         } else {
 443                 tid[0] = 0;
 444         }
 445
 446         if (descriptor->flags & _DPRINTK_FLAGS_INCL_LINENO)
 447                 snprintf(lineno, sizeof(lineno), "%d", descriptor->lineno);
 448         else
 449                 lineno[0] = 0;
 450
 451         return printk(KERN_DEBUG "%s%s%s%s%s%s",
 452                       tid,
 453                       (descriptor->flags & _DPRINTK_FLAGS_INCL_MODNAME) ?
 454                       descriptor->modname : "",
 455                       (descriptor->flags & _DPRINTK_FLAGS_INCL_MODNAME) ?
 456                       ":" : "",
 457                       (descriptor->flags & _DPRINTK_FLAGS_INCL_FUNCNAME) ?
 458                       descriptor->function : "",
 459                       (descriptor->flags & _DPRINTK_FLAGS_INCL_FUNCNAME) ?
 460                       ":" : "",
 461                       lineno);
 462 }
 463
 464 int __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...)
 465 {
 466         va_list args;
 467         int res;
 468
 469         BUG_ON(!descriptor);
 470         BUG_ON(!fmt);
 471
 472         va_start(args, fmt);
 473
 474         res = dynamic_emit_prefix(descriptor);
 475         res += vprintk(fmt, args);
 476
 477         va_end(args);
 478
 479         return res;
 480 }
 481 EXPORT_SYMBOL(__dynamic_pr_debug);
 482
 483 int __dynamic_dev_dbg(struct _ddebug *descriptor,
 484                       const struct device *dev, const char *fmt, ...)
 485 {
 486         struct va_format vaf;
 487         va_list args;
 488         int res;
 489
 490         BUG_ON(!descriptor);
 491         BUG_ON(!fmt);
 492
 493         va_start(args, fmt);
 494
 495         vaf.fmt = fmt;
 496         vaf.va = &args;
 497
 498         res = dynamic_emit_prefix(descriptor);
 499         res += __dev_printk(KERN_CONT, dev, &vaf);
 500
 501         va_end(args);
 502
 503         return res;
 504 }
 505 EXPORT_SYMBOL(__dynamic_dev_dbg);
 506
 507 int __dynamic_netdev_dbg(struct _ddebug *descriptor,
 508                       const struct net_device *dev, const char *fmt, ...)
 509 {
 510         struct va_format vaf;
 511         va_list args;
 512         int res;
 513
 514         BUG_ON(!descriptor);
 515         BUG_ON(!fmt);
 516
 517         va_start(args, fmt);
 518
 519         vaf.fmt = fmt;
 520         vaf.va = &args;
 521
 522         res = dynamic_emit_prefix(descriptor);
 523         res += __netdev_printk(KERN_CONT, dev, &vaf);
 524
 525         va_end(args);
 526
 527         return res;
 528 }
 529 EXPORT_SYMBOL(__dynamic_netdev_dbg);
 530
 531 static __initdata char ddebug_setup_string[1024];
 532 static __init int ddebug_setup_query(char *str)
 533 {
 534         if (strlen(str) >= 1024) {
 535                 pr_warn("ddebug boot param string too large\n");
 536                 return 0;
 537         }
 538         strcpy(ddebug_setup_string, str);
 539         return 1;
 540 }
 541
 542 __setup("ddebug_query=", ddebug_setup_query);
 543
 544 /*
 545  * File_ops->write method for <debugfs>/dynamic_debug/conrol.  Gathers the
 546  * command text from userspace, parses and executes it.
 547  */
 548 static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
 549                                   size_t len, loff_t *offp)
 550 {
 551         char tmpbuf[256];
 552         int ret;
 553
 554         if (len == 0)
 555                 return 0;
 556         /* we don't check *offp -- multiple writes() are allowed */
 557         if (len > sizeof(tmpbuf)-1)
 558                 return -E2BIG;
 559         if (copy_from_user(tmpbuf, ubuf, len))
 560                 return -EFAULT;
 561         tmpbuf[len] = '\0';
 562         if (verbose)
 563                 pr_info("read %d bytes from userspace\n", (int)len);
 564
 565         ret = ddebug_exec_query(tmpbuf);
 566         if (ret)
 567                 return ret;
 568
 569         *offp += len;
 570         return len;
 571 }
 572
 573 /*
 574  * Set the iterator to point to the first _ddebug object
 575  * and return a pointer to that first object.  Returns
 576  * NULL if there are no _ddebugs at all.
 577  */
 578 static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
 579 {
 580         if (list_empty(&ddebug_tables)) {
 581                 iter->table = NULL;
 582                 iter->idx = 0;
 583                 return NULL;
 584         }
 585         iter->table = list_entry(ddebug_tables.next,
 586                                  struct ddebug_table, link);
 587         iter->idx = 0;
 588         return &iter->table->ddebugs[iter->idx];
 589 }
 590
 591 /*
 592  * Advance the iterator to point to the next _ddebug
 593  * object from the one the iterator currently points at,
 594  * and returns a pointer to the new _ddebug.  Returns
 595  * NULL if the iterator has seen all the _ddebugs.
 596  */
 597 static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
 598 {
 599         if (iter->table == NULL)
 600                 return NULL;
 601         if (++iter->idx == iter->table->num_ddebugs) {
 602                 /* iterate to next table */
 603                 iter->idx = 0;
 604                 if (list_is_last(&iter->table->link, &ddebug_tables)) {
 605                         iter->table = NULL;
 606                         return NULL;
 607                 }
 608                 iter->table = list_entry(iter->table->link.next,
 609                                          struct ddebug_table, link);
 610         }
 611         return &iter->table->ddebugs[iter->idx];
 612 }
 613
 614 /*
 615  * Seq_ops start method.  Called at the start of every
 616  * read() call from userspace.  Takes the ddebug_lock and
 617  * seeks the seq_file's iterator to the given position.
 618  */
 619 static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
 620 {
 621         struct ddebug_iter *iter = m->private;
 622         struct _ddebug *dp;
 623         int n = *pos;
 624
 625         if (verbose)
 626                 pr_info("called m=%p *pos=%lld\n", m, (unsigned long long)*pos);
 627
 628         mutex_lock(&ddebug_lock);
 629
 630         if (!n)
 631                 return SEQ_START_TOKEN;
 632         if (n < 0)
 633                 return NULL;
 634         dp = ddebug_iter_first(iter);
 635         while (dp != NULL && --n > 0)
 636                 dp = ddebug_iter_next(iter);
 637         return dp;
 638 }
 639
 640 /*
 641  * Seq_ops next method.  Called several times within a read()
 642  * call from userspace, with ddebug_lock held.  Walks to the
 643  * next _ddebug object with a special case for the header line.
 644  */
 645 static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
 646 {
 647         struct ddebug_iter *iter = m->private;
 648         struct _ddebug *dp;
 649
 650         if (verbose)
 651                 pr_info("called m=%p p=%p *pos=%lld\n",
 652                         m, p, (unsigned long long)*pos);
 653
 654         if (p == SEQ_START_TOKEN)
 655                 dp = ddebug_iter_first(iter);
 656         else
 657                 dp = ddebug_iter_next(iter);
 658         ++*pos;
 659         return dp;
 660 }
 661
 662 /*
 663  * Seq_ops show method.  Called several times within a read()
 664  * call from userspace, with ddebug_lock held.  Formats the
 665  * current _ddebug as a single human-readable line, with a
 666  * special case for the header line.
 667  */
 668 static int ddebug_proc_show(struct seq_file *m, void *p)
 669 {
 670         struct ddebug_iter *iter = m->private;
 671         struct _ddebug *dp = p;
 672         char flagsbuf[8];
 673
 674         if (verbose)
 675                 pr_info("called m=%p p=%p\n", m, p);
 676
 677         if (p == SEQ_START_TOKEN) {
 678                 seq_puts(m,
 679                         "# filename:lineno [module]function flags format\n");
 680                 return 0;
 681         }
 682
 683         seq_printf(m, "%s:%u [%s]%s %s \"",
 684                    dp->filename, dp->lineno,
 685                    iter->table->mod_name, dp->function,
 686                    ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
 687         seq_escape(m, dp->format, "\t\r\n\"");
 688         seq_puts(m, "\"\n");
 689
 690         return 0;
 691 }
 692
 693 /*
 694  * Seq_ops stop method.  Called at the end of each read()
 695  * call from userspace.  Drops ddebug_lock.
 696  */
 697 static void ddebug_proc_stop(struct seq_file *m, void *p)
 698 {
 699         if (verbose)
 700                 pr_info("called m=%p p=%p\n", m, p);
 701         mutex_unlock(&ddebug_lock);
 702 }
 703
 704 static const struct seq_operations ddebug_proc_seqops = {
 705         .start = ddebug_proc_start,
 706         .next = ddebug_proc_next,
 707         .show = ddebug_proc_show,
 708         .stop = ddebug_proc_stop
 709 };
 710
 711 /*
 712  * File_ops->open method for <debugfs>/dynamic_debug/control.  Does the seq_file
 713  * setup dance, and also creates an iterator to walk the _ddebugs.
 714  * Note that we create a seq_file always, even for O_WRONLY files
 715  * where it's not needed, as doing so simplifies the ->release method.
 716  */
 717 static int ddebug_proc_open(struct inode *inode, struct file *file)
 718 {
 719         struct ddebug_iter *iter;
 720         int err;
 721
 722         if (verbose)
 723                 pr_info("called\n");
 724
 725         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
 726         if (iter == NULL)
 727                 return -ENOMEM;
 728
 729         err = seq_open(file, &ddebug_proc_seqops);
 730         if (err) {
 731                 kfree(iter);
 732                 return err;
 733         }
 734         ((struct seq_file *) file->private_data)->private = iter;
 735         return 0;
 736 }
 737
 738 static const struct file_operations ddebug_proc_fops = {
 739         .owner = THIS_MODULE,
 740         .open = ddebug_proc_open,
 741         .read = seq_read,
 742         .llseek = seq_lseek,
 743         .release = seq_release_private,
 744         .write = ddebug_proc_write
 745 };
 746
 747 /*
 748  * Allocate a new ddebug_table for the given module
 749  * and add it to the global list.
 750  */
 751 int ddebug_add_module(struct _ddebug *tab, unsigned int n,
 752                              const char *name)
 753 {
 754         struct ddebug_table *dt;
 755         char *new_name;
 756
 757         dt = kzalloc(sizeof(*dt), GFP_KERNEL);
 758         if (dt == NULL)
 759                 return -ENOMEM;
 760         new_name = kstrdup(name, GFP_KERNEL);
 761         if (new_name == NULL) {
 762                 kfree(dt);
 763                 return -ENOMEM;
 764         }
 765         dt->mod_name = new_name;
 766         dt->num_ddebugs = n;
 767         dt->num_enabled = 0;
 768         dt->ddebugs = tab;
 769
 770         mutex_lock(&ddebug_lock);
 771         list_add_tail(&dt->link, &ddebug_tables);
 772         mutex_unlock(&ddebug_lock);
 773
 774         if (verbose)
 775                 pr_info("%u debug prints in module %s\n", n, dt->mod_name);
 776         return 0;
 777 }
 778 EXPORT_SYMBOL_GPL(ddebug_add_module);
 779
 780 static void ddebug_table_free(struct ddebug_table *dt)
 781 {
 782         list_del_init(&dt->link);
 783         kfree(dt->mod_name);
 784         kfree(dt);
 785 }
 786
 787 /*
 788  * Called in response to a module being unloaded.  Removes
 789  * any ddebug_table's which point at the module.
 790  */
 791 int ddebug_remove_module(const char *mod_name)
 792 {
 793         struct ddebug_table *dt, *nextdt;
 794         int ret = -ENOENT;
 795
 796         if (verbose)
 797                 pr_info("removing module \"%s\"\n", mod_name);
 798
 799         mutex_lock(&ddebug_lock);
 800         list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
 801                 if (!strcmp(dt->mod_name, mod_name)) {
 802                         ddebug_table_free(dt);
 803                         ret = 0;
 804                 }
 805         }
 806         mutex_unlock(&ddebug_lock);
 807         return ret;
 808 }
 809 EXPORT_SYMBOL_GPL(ddebug_remove_module);
 810
 811 static void ddebug_remove_all_tables(void)
 812 {
 813         mutex_lock(&ddebug_lock);
 814         while (!list_empty(&ddebug_tables)) {
 815                 struct ddebug_table *dt = list_entry(ddebug_tables.next,
 816                                                       struct ddebug_table,
 817                                                       link);
 818                 ddebug_table_free(dt);
 819         }
 820         mutex_unlock(&ddebug_lock);
 821 }
 822
 823 static __initdata int ddebug_init_success;
 824
 825 static int __init dynamic_debug_init_debugfs(void)
 826 {
 827         struct dentry *dir, *file;
 828
 829         if (!ddebug_init_success)
 830                 return -ENODEV;
 831
 832         dir = debugfs_create_dir("dynamic_debug", NULL);
 833         if (!dir)
 834                 return -ENOMEM;
 835         file = debugfs_create_file("control", 0644, dir, NULL,
 836                                         &ddebug_proc_fops);
 837         if (!file) {
 838                 debugfs_remove(dir);
 839                 return -ENOMEM;
 840         }
 841         return 0;
 842 }
 843
 844 static int __init dynamic_debug_init(void)
 845 {
 846         struct _ddebug *iter, *iter_start;
 847         const char *modname = NULL;
 848         int ret = 0;
 849         int n = 0;
 850
 851         if (__start___verbose != __stop___verbose) {
 852                 iter = __start___verbose;
 853                 modname = iter->modname;
 854                 iter_start = iter;
 855                 for (; iter < __stop___verbose; iter++) {
 856                         if (strcmp(modname, iter->modname)) {
 857                                 ret = ddebug_add_module(iter_start, n, modname);
 858                                 if (ret)
 859                                         goto out_free;
 860                                 n = 0;
 861                                 modname = iter->modname;
 862                                 iter_start = iter;
 863                         }
 864                         n++;
 865                 }
 866                 ret = ddebug_add_module(iter_start, n, modname);
 867         }
 868
 869         /* ddebug_query boot param got passed -> set it up */
 870         if (ddebug_setup_string[0] != '\0') {
 871                 ret = ddebug_exec_query(ddebug_setup_string);
 872                 if (ret)
 873                         pr_warn("Invalid ddebug boot param %s",
 874                                 ddebug_setup_string);
 875                 else
 876                         pr_info("ddebug initialized with string %s",
 877                                 ddebug_setup_string);
 878         }
 879
 880 out_free:
 881         if (ret)
 882                 ddebug_remove_all_tables();
 883         else
 884                 ddebug_init_success = 1;
 885         return 0;
 886 }
 887 /* Allow early initialization for boot messages via boot param */
 888 arch_initcall(dynamic_debug_init);
 889 /* Debugfs setup must be done later */
 890 module_init(dynamic_debug_init_debugfs);