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