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