src/patches/suse-2.6.27.25/patches.drivers/driver-core-basic-infrastructure-for-per-module-dynamic-debug-messages.patch

   1 From jbaron@redhat.com  Tue Aug 12 17:09:39 2008
   2 From: Jason Baron <jbaron@redhat.com>
   3 Date: Tue, 12 Aug 2008 16:46:19 -0400
   4 Subject: driver core: basic infrastructure for per-module dynamic debug messages
   5 To: Greg KH <greg@kroah.com>
   6 Cc: Randy Dunlap <randy.dunlap@oracle.com>, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, joe@perches.com, nick@nick-andrew.net
   7 Message-ID: <20080812204619.GE6056@redhat.com>
   8 Patch-mainline: 2.6.28
   9
  10 Base infrastructure to enable per-module debug messages.
  11
  12 I've introduced CONFIG_DYNAMIC_PRINTK_DEBUG, which when enabled centralizes
  13 control of debugging statements on a per-module basis in one /proc file,
  14 currently, <debugfs>/dynamic_printk/modules. When, CONFIG_DYNAMIC_PRINTK_DEBUG,
  15 is not set, debugging statements can still be enabled as before, often by
  16 defining 'DEBUG' for the proper compilation unit. Thus, this patch set has no
  17 affect when CONFIG_DYNAMIC_PRINTK_DEBUG is not set.
  18
  19 The infrastructure currently ties into all pr_debug() and dev_dbg() calls. That
  20 is, if CONFIG_DYNAMIC_PRINTK_DEBUG is set, all pr_debug() and dev_dbg() calls
  21 can be dynamically enabled/disabled on a per-module basis.
  22
  23 Future plans include extending this functionality to subsystems, that define
  24 their own debug levels and flags.
  25
  26 Usage:
  27
  28 Dynamic debugging is controlled by the debugfs file,
  29 <debugfs>/dynamic_printk/modules. This file contains a list of the modules that
  30 can be enabled. The format of the file is as follows:
  31
  32         <module_name> <enabled=0/1>
  33                 .
  34                 .
  35                 .
  36
  37         <module_name> : Name of the module in which the debug call resides
  38         <enabled=0/1> : whether the messages are enabled or not
  39
  40 For example:
  41
  42         snd_hda_intel enabled=0
  43         fixup enabled=1
  44         driver enabled=0
  45
  46 Enable a module:
  47
  48         $echo "set enabled=1 <module_name>" > dynamic_printk/modules
  49
  50 Disable a module:
  51
  52         $echo "set enabled=0 <module_name>" > dynamic_printk/modules
  53
  54 Enable all modules:
  55
  56         $echo "set enabled=1 all" > dynamic_printk/modules
  57
  58 Disable all modules:
  59
  60         $echo "set enabled=0 all" > dynamic_printk/modules
  61
  62 Finally, passing "dynamic_printk" at the command line enables
  63 debugging for all modules. This mode can be turned off via the above
  64 disable command.
  65
  66 [gkh: minor cleanups and tweaks to make the build work quietly]
  67
  68 Signed-off-by: Jason Baron <jbaron@redhat.com>
  69 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  70
  71
  72 ---
  73  Documentation/kernel-parameters.txt |    5
  74  include/asm-generic/vmlinux.lds.h   |   10
  75  include/linux/device.h              |    6
  76  include/linux/dynamic_printk.h      |   93 ++++++++
  77  include/linux/kernel.h              |    7
  78  include/linux/module.h              |    1
  79  kernel/module.c                     |   31 ++
  80  lib/Kconfig.debug                   |   55 ++++
  81  lib/Makefile                        |    2
  82  lib/dynamic_printk.c                |  418 ++++++++++++++++++++++++++++++++++++
  83  net/netfilter/nf_conntrack_pptp.c   |    2
  84  scripts/Makefile.lib                |   11
  85  scripts/basic/Makefile              |    2
  86  scripts/basic/hash.c                |   64 +++++
  87  14 files changed, 700 insertions(+), 7 deletions(-)
  88
  89 --- a/Documentation/kernel-parameters.txt
  90 +++ b/Documentation/kernel-parameters.txt
  91 @@ -1735,6 +1735,11 @@ and is between 256 and 4096 characters.
  92                         autoconfiguration.
  93                         Ranges are in pairs (memory base and size).
  94
  95 +       dynamic_printk
  96 +                       Enables pr_debug()/dev_dbg() calls if
  97 +                       CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
  98 +                       be switched on/off via <debugfs>/dynamic_printk/modules
  99 +
 100         print-fatal-signals=
 101                         [KNL] debug: print fatal signals
 102                         print-fatal-signals=1: print segfault info to
 103 --- a/include/asm-generic/vmlinux.lds.h
 104 +++ b/include/asm-generic/vmlinux.lds.h
 105 @@ -268,7 +268,15 @@
 106         CPU_DISCARD(init.data)                                          \
 107         CPU_DISCARD(init.rodata)                                        \
 108         MEM_DISCARD(init.data)                                          \
 109 -       MEM_DISCARD(init.rodata)
 110 +       MEM_DISCARD(init.rodata)                                        \
 111 +       /* implement dynamic printk debug */                            \
 112 +       VMLINUX_SYMBOL(__start___verbose_strings) = .;                  \
 113 +       *(__verbose_strings)                                            \
 114 +       VMLINUX_SYMBOL(__stop___verbose_strings) = .;                   \
 115 +       . = ALIGN(8);                                                   \
 116 +       VMLINUX_SYMBOL(__start___verbose) = .;                          \
 117 +       *(__verbose)                                                    \
 118 +       VMLINUX_SYMBOL(__stop___verbose) = .;
 119
 120  #define INIT_TEXT                                                      \
 121         *(.init.text)                                                   \
 122 --- a/include/linux/device.h
 123 +++ b/include/linux/device.h
 124 @@ -553,7 +553,11 @@ int printk_dev_hash(const char *, const
 125  #define dev_info(dev, format, arg...)          \
 126         dev_printk_hash(KERN_INFO , dev , format , ## arg)
 127
 128 -#ifdef DEBUG
 129 +#if defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
 130 +#define dev_dbg(dev, format, ...) do { \
 131 +       dynamic_dev_dbg(dev, format, ##__VA_ARGS__); \
 132 +       } while (0)
 133 +#elif defined(DEBUG)
 134  #define dev_dbg(dev, format, arg...)           \
 135         dev_printk(KERN_DEBUG , dev , format , ## arg)
 136  #else
 137 --- /dev/null
 138 +++ b/include/linux/dynamic_printk.h
 139 @@ -0,0 +1,93 @@
 140 +#ifndef _DYNAMIC_PRINTK_H
 141 +#define _DYNAMIC_PRINTK_H
 142 +
 143 +#define DYNAMIC_DEBUG_HASH_BITS 6
 144 +#define DEBUG_HASH_TABLE_SIZE (1 << DYNAMIC_DEBUG_HASH_BITS)
 145 +
 146 +#define TYPE_BOOLEAN 1
 147 +
 148 +#define DYNAMIC_ENABLED_ALL 0
 149 +#define DYNAMIC_ENABLED_NONE 1
 150 +#define DYNAMIC_ENABLED_SOME 2
 151 +
 152 +extern int dynamic_enabled;
 153 +
 154 +/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
 155 + * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
 156 + * use independent hash functions, to reduce the chance of false positives.
 157 + */
 158 +extern long long dynamic_printk_enabled;
 159 +extern long long dynamic_printk_enabled2;
 160 +
 161 +struct mod_debug {
 162 +       char *modname;
 163 +       char *logical_modname;
 164 +       char *flag_names;
 165 +       int type;
 166 +       int hash;
 167 +       int hash2;
 168 +} __attribute__((aligned(8)));
 169 +
 170 +int register_dynamic_debug_module(char *mod_name, int type, char *share_name,
 171 +                                       char *flags, int hash, int hash2);
 172 +
 173 +#if defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
 174 +extern int unregister_dynamic_debug_module(char *mod_name);
 175 +extern int __dynamic_dbg_enabled_helper(char *modname, int type,
 176 +                                       int value, int hash);
 177 +
 178 +#define __dynamic_dbg_enabled(module, type, value, level, hash)  ({         \
 179 +       int __ret = 0;                                                       \
 180 +       if (unlikely((dynamic_printk_enabled & (1LL << DEBUG_HASH)) &&       \
 181 +                       (dynamic_printk_enabled2 & (1LL << DEBUG_HASH2))))   \
 182 +                       __ret = __dynamic_dbg_enabled_helper(module, type,   \
 183 +                                                               value, hash);\
 184 +       __ret; })
 185 +
 186 +#define dynamic_pr_debug(fmt, ...) do {                                            \
 187 +       static char mod_name[]                                              \
 188 +       __attribute__((section("__verbose_strings")))                       \
 189 +        = KBUILD_MODNAME;                                                  \
 190 +       static struct mod_debug descriptor                                  \
 191 +       __used                                                              \
 192 +       __attribute__((section("__verbose"), aligned(8))) =                 \
 193 +       { mod_name, mod_name, NULL, TYPE_BOOLEAN, DEBUG_HASH, DEBUG_HASH2 };\
 194 +       if (__dynamic_dbg_enabled(KBUILD_MODNAME, TYPE_BOOLEAN,             \
 195 +                                               0, 0, DEBUG_HASH))          \
 196 +               printk(KERN_DEBUG KBUILD_MODNAME ":" fmt,                   \
 197 +                               ##__VA_ARGS__);                             \
 198 +       } while (0)
 199 +
 200 +#define dynamic_dev_dbg(dev, format, ...) do {                             \
 201 +       static char mod_name[]                                              \
 202 +       __attribute__((section("__verbose_strings")))                       \
 203 +        = KBUILD_MODNAME;                                                  \
 204 +       static struct mod_debug descriptor                                  \
 205 +       __used                                                              \
 206 +       __attribute__((section("__verbose"), aligned(8))) =                 \
 207 +       { mod_name, mod_name, NULL, TYPE_BOOLEAN, DEBUG_HASH, DEBUG_HASH2 };\
 208 +       if (__dynamic_dbg_enabled(KBUILD_MODNAME, TYPE_BOOLEAN,             \
 209 +                                               0, 0, DEBUG_HASH))          \
 210 +                       dev_printk(KERN_DEBUG, dev,                         \
 211 +                                       KBUILD_MODNAME ": " format,         \
 212 +                                       ##__VA_ARGS__);                     \
 213 +       } while (0)
 214 +
 215 +#else
 216 +
 217 +static inline int unregister_dynamic_debug_module(const char *mod_name)
 218 +{
 219 +       return 0;
 220 +}
 221 +static inline int __dynamic_dbg_enabled_helper(char *modname, int type,
 222 +                                               int value, int hash)
 223 +{
 224 +       return 0;
 225 +}
 226 +
 227 +#define __dynamic_dbg_enabled(module, type, value, level, hash)  ({ 0; })
 228 +#define dynamic_pr_debug(fmt, ...)  do { } while (0)
 229 +#define dynamic_dev_dbg(dev, format, ...)  do { } while (0)
 230 +#endif
 231 +
 232 +#endif
 233 --- a/include/linux/kernel.h
 234 +++ b/include/linux/kernel.h
 235 @@ -16,6 +16,7 @@
 236  #include <linux/log2.h>
 237  #include <linux/typecheck.h>
 238  #include <linux/ratelimit.h>
 239 +#include <linux/dynamic_printk.h>
 240  #include <asm/byteorder.h>
 241  #include <asm/bug.h>
 242
 243 @@ -331,8 +332,12 @@ int printk_hash(const char *, const char
 244  #define pr_info(fmt, arg...) \
 245         pr_printk_hash(KERN_INFO, fmt, ##arg)
 246
 247 -#ifdef DEBUG
 248  /* If you are writing a driver, please use dev_dbg instead */
 249 +#if defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
 250 +#define pr_debug(fmt, ...) do { \
 251 +       dynamic_pr_debug(fmt, ##__VA_ARGS__); \
 252 +       } while (0)
 253 +#elif defined(DEBUG)
 254  #define pr_debug(fmt, arg...) \
 255         pr_printk(KERN_DEBUG, fmt, ##arg)
 256  #else
 257 --- a/include/linux/module.h
 258 +++ b/include/linux/module.h
 259 @@ -345,7 +345,6 @@ struct module
 260         /* Reference counts */
 261         struct module_ref ref[NR_CPUS];
 262  #endif
 263 -
 264  };
 265  #ifndef MODULE_ARCH_INIT
 266  #define MODULE_ARCH_INIT {}
 267 --- a/kernel/module.c
 268 +++ b/kernel/module.c
 269 @@ -798,6 +798,7 @@ SYSCALL_DEFINE2(delete_module, const cha
 270         mutex_lock(&module_mutex);
 271         /* Store the name of the last unloaded module for diagnostic purposes */
 272         strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));
 273 +       unregister_dynamic_debug_module(mod->name);
 274         free_module(mod);
 275
 276   out:
 277 @@ -1823,6 +1824,33 @@ static inline void add_kallsyms(struct m
 278  }
 279  #endif /* CONFIG_KALLSYMS */
 280
 281 +#ifdef CONFIG_DYNAMIC_PRINTK_DEBUG
 282 +static void dynamic_printk_setup(Elf_Shdr *sechdrs, unsigned int verboseindex)
 283 +{
 284 +       struct mod_debug *debug_info;
 285 +       unsigned long pos, end;
 286 +       unsigned int num_verbose;
 287 +
 288 +       pos = sechdrs[verboseindex].sh_addr;
 289 +       num_verbose = sechdrs[verboseindex].sh_size /
 290 +                               sizeof(struct mod_debug);
 291 +       end = pos + (num_verbose * sizeof(struct mod_debug));
 292 +
 293 +       for (; pos < end; pos += sizeof(struct mod_debug)) {
 294 +               debug_info = (struct mod_debug *)pos;
 295 +               register_dynamic_debug_module(debug_info->modname,
 296 +                       debug_info->type, debug_info->logical_modname,
 297 +                       debug_info->flag_names, debug_info->hash,
 298 +                       debug_info->hash2);
 299 +       }
 300 +}
 301 +#else
 302 +static inline void dynamic_printk_setup(Elf_Shdr *sechdrs,
 303 +                                       unsigned int verboseindex)
 304 +{
 305 +}
 306 +#endif /* CONFIG_DYNAMIC_PRINTK_DEBUG */
 307 +
 308  static void *module_alloc_update_bounds(unsigned long size)
 309  {
 310         void *ret = module_alloc(size);
 311 @@ -1871,6 +1899,7 @@ static noinline struct module *load_modu
 312  #endif
 313         unsigned int markersindex;
 314         unsigned int markersstringsindex;
 315 +       unsigned int verboseindex;
 316         struct module *mod;
 317         long err = 0;
 318         void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
 319 @@ -2157,6 +2186,7 @@ static noinline struct module *load_modu
 320         markersindex = find_sec(hdr, sechdrs, secstrings, "__markers");
 321         markersstringsindex = find_sec(hdr, sechdrs, secstrings,
 322                                         "__markers_strings");
 323 +       verboseindex = find_sec(hdr, sechdrs, secstrings, "__verbose");
 324
 325         /* Now do relocations. */
 326         for (i = 1; i < hdr->e_shnum; i++) {
 327 @@ -2207,6 +2237,7 @@ static noinline struct module *load_modu
 328                 marker_update_probe_range(mod->markers,
 329                         mod->markers + mod->num_markers);
 330  #endif
 331 +       dynamic_printk_setup(sechdrs, verboseindex);
 332         err = module_finalize(hdr, sechdrs, mod);
 333         if (err < 0)
 334                 goto cleanup;
 335 --- /dev/null
 336 +++ b/lib/dynamic_printk.c
 337 @@ -0,0 +1,418 @@
 338 +/*
 339 + * lib/dynamic_printk.c
 340 + *
 341 + * make pr_debug()/dev_dbg() calls runtime configurable based upon their
 342 + * their source module.
 343 + *
 344 + * Copyright (C) 2008 Red Hat, Inc., Jason Baron <jbaron@redhat.com>
 345 + */
 346 +
 347 +#include <linux/kernel.h>
 348 +#include <linux/module.h>
 349 +#include <linux/uaccess.h>
 350 +#include <linux/seq_file.h>
 351 +#include <linux/debugfs.h>
 352 +#include <linux/fs.h>
 353 +
 354 +extern struct mod_debug __start___verbose[];
 355 +extern struct mod_debug __stop___verbose[];
 356 +
 357 +struct debug_name {
 358 +       struct hlist_node hlist;
 359 +       struct hlist_node hlist2;
 360 +       int hash1;
 361 +       int hash2;
 362 +       char *name;
 363 +       int enable;
 364 +       int type;
 365 +};
 366 +
 367 +static int nr_entries;
 368 +static int num_enabled;
 369 +int dynamic_enabled = DYNAMIC_ENABLED_NONE;
 370 +static struct hlist_head module_table[DEBUG_HASH_TABLE_SIZE] =
 371 +       { [0 ... DEBUG_HASH_TABLE_SIZE-1] = HLIST_HEAD_INIT };
 372 +static struct hlist_head module_table2[DEBUG_HASH_TABLE_SIZE] =
 373 +       { [0 ... DEBUG_HASH_TABLE_SIZE-1] = HLIST_HEAD_INIT };
 374 +static DECLARE_MUTEX(debug_list_mutex);
 375 +
 376 +/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
 377 + * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
 378 + * use independent hash functions, to reduce the chance of false positives.
 379 + */
 380 +long long dynamic_printk_enabled;
 381 +EXPORT_SYMBOL_GPL(dynamic_printk_enabled);
 382 +long long dynamic_printk_enabled2;
 383 +EXPORT_SYMBOL_GPL(dynamic_printk_enabled2);
 384 +
 385 +/* returns the debug module pointer. */
 386 +static struct debug_name *find_debug_module(char *module_name)
 387 +{
 388 +       int i;
 389 +       struct hlist_head *head;
 390 +       struct hlist_node *node;
 391 +       struct debug_name *element;
 392 +
 393 +       element = NULL;
 394 +       for (i = 0; i < DEBUG_HASH_TABLE_SIZE; i++) {
 395 +               head = &module_table[i];
 396 +               hlist_for_each_entry_rcu(element, node, head, hlist)
 397 +                       if (!strcmp(element->name, module_name))
 398 +                               return element;
 399 +       }
 400 +       return NULL;
 401 +}
 402 +
 403 +/* returns the debug module pointer. */
 404 +static struct debug_name *find_debug_module_hash(char *module_name, int hash)
 405 +{
 406 +       struct hlist_head *head;
 407 +       struct hlist_node *node;
 408 +       struct debug_name *element;
 409 +
 410 +       element = NULL;
 411 +       head = &module_table[hash];
 412 +       hlist_for_each_entry_rcu(element, node, head, hlist)
 413 +               if (!strcmp(element->name, module_name))
 414 +                       return element;
 415 +       return NULL;
 416 +}
 417 +
 418 +/* caller must hold mutex*/
 419 +static int __add_debug_module(char *mod_name, int hash, int hash2)
 420 +{
 421 +       struct debug_name *new;
 422 +       char *module_name;
 423 +       int ret = 0;
 424 +
 425 +       if (find_debug_module(mod_name)) {
 426 +               ret = -EINVAL;
 427 +               goto out;
 428 +       }
 429 +       module_name = kmalloc(strlen(mod_name) + 1, GFP_KERNEL);
 430 +       if (!module_name) {
 431 +               ret = -ENOMEM;
 432 +               goto out;
 433 +       }
 434 +       module_name = strcpy(module_name, mod_name);
 435 +       module_name[strlen(mod_name)] = '\0';
 436 +       new = kzalloc(sizeof(struct debug_name), GFP_KERNEL);
 437 +       if (!new) {
 438 +               kfree(module_name);
 439 +               ret = -ENOMEM;
 440 +               goto out;
 441 +       }
 442 +       INIT_HLIST_NODE(&new->hlist);
 443 +       INIT_HLIST_NODE(&new->hlist2);
 444 +       new->name = module_name;
 445 +       new->hash1 = hash;
 446 +       new->hash2 = hash2;
 447 +       hlist_add_head_rcu(&new->hlist, &module_table[hash]);
 448 +       hlist_add_head_rcu(&new->hlist2, &module_table2[hash2]);
 449 +       nr_entries++;
 450 +out:
 451 +       return ret;
 452 +}
 453 +
 454 +int unregister_dynamic_debug_module(char *mod_name)
 455 +{
 456 +       struct debug_name *element;
 457 +       int ret = 0;
 458 +
 459 +       down(&debug_list_mutex);
 460 +       element = find_debug_module(mod_name);
 461 +       if (!element) {
 462 +               ret = -EINVAL;
 463 +               goto out;
 464 +       }
 465 +       hlist_del_rcu(&element->hlist);
 466 +       hlist_del_rcu(&element->hlist2);
 467 +       synchronize_rcu();
 468 +       kfree(element->name);
 469 +       if (element->enable)
 470 +               num_enabled--;
 471 +       kfree(element);
 472 +       nr_entries--;
 473 +out:
 474 +       up(&debug_list_mutex);
 475 +       return 0;
 476 +}
 477 +EXPORT_SYMBOL_GPL(unregister_dynamic_debug_module);
 478 +
 479 +int register_dynamic_debug_module(char *mod_name, int type, char *share_name,
 480 +                                       char *flags, int hash, int hash2)
 481 +{
 482 +       struct debug_name *elem;
 483 +       int ret = 0;
 484 +
 485 +       down(&debug_list_mutex);
 486 +       elem = find_debug_module(mod_name);
 487 +       if (!elem) {
 488 +               if (__add_debug_module(mod_name, hash, hash2))
 489 +                       goto out;
 490 +               elem = find_debug_module(mod_name);
 491 +               if (dynamic_enabled == DYNAMIC_ENABLED_ALL &&
 492 +                               !strcmp(mod_name, share_name)) {
 493 +                       elem->enable = true;
 494 +                       num_enabled++;
 495 +               }
 496 +       }
 497 +       elem->type |= type;
 498 +out:
 499 +       up(&debug_list_mutex);
 500 +       return ret;
 501 +}
 502 +EXPORT_SYMBOL_GPL(register_dynamic_debug_module);
 503 +
 504 +int __dynamic_dbg_enabled_helper(char *mod_name, int type, int value, int hash)
 505 +{
 506 +       struct debug_name *elem;
 507 +       int ret = 0;
 508 +
 509 +       if (dynamic_enabled == DYNAMIC_ENABLED_ALL)
 510 +               return 1;
 511 +       rcu_read_lock();
 512 +       elem = find_debug_module_hash(mod_name, hash);
 513 +       if (elem && elem->enable)
 514 +               ret = 1;
 515 +       rcu_read_unlock();
 516 +       return ret;
 517 +}
 518 +EXPORT_SYMBOL_GPL(__dynamic_dbg_enabled_helper);
 519 +
 520 +static void set_all(bool enable)
 521 +{
 522 +       struct debug_name *e;
 523 +       struct hlist_node *node;
 524 +       int i;
 525 +       long long enable_mask;
 526 +
 527 +       for (i = 0; i < DEBUG_HASH_TABLE_SIZE; i++) {
 528 +               if (module_table[i].first != NULL) {
 529 +                       hlist_for_each_entry(e, node, &module_table[i], hlist) {
 530 +                               e->enable = enable;
 531 +                       }
 532 +               }
 533 +       }
 534 +       if (enable)
 535 +               enable_mask = ULLONG_MAX;
 536 +       else
 537 +               enable_mask = 0;
 538 +       dynamic_printk_enabled = enable_mask;
 539 +       dynamic_printk_enabled2 = enable_mask;
 540 +}
 541 +
 542 +static int disabled_hash(int i, bool first_table)
 543 +{
 544 +       struct debug_name *e;
 545 +       struct hlist_node *node;
 546 +
 547 +       if (first_table) {
 548 +               hlist_for_each_entry(e, node, &module_table[i], hlist) {
 549 +                       if (e->enable)
 550 +                               return 0;
 551 +               }
 552 +       } else {
 553 +               hlist_for_each_entry(e, node, &module_table2[i], hlist2) {
 554 +                       if (e->enable)
 555 +                               return 0;
 556 +               }
 557 +       }
 558 +       return 1;
 559 +}
 560 +
 561 +static ssize_t pr_debug_write(struct file *file, const char __user *buf,
 562 +                               size_t length, loff_t *ppos)
 563 +{
 564 +       char *buffer, *s, *value_str, *setting_str;
 565 +       int err, value;
 566 +       struct debug_name *elem = NULL;
 567 +       int all = 0;
 568 +
 569 +       if (length > PAGE_SIZE || length < 0)
 570 +               return -EINVAL;
 571 +
 572 +       buffer = (char *)__get_free_page(GFP_KERNEL);
 573 +       if (!buffer)
 574 +               return -ENOMEM;
 575 +
 576 +       err = -EFAULT;
 577 +       if (copy_from_user(buffer, buf, length))
 578 +               goto out;
 579 +
 580 +       err = -EINVAL;
 581 +       if (length < PAGE_SIZE)
 582 +               buffer[length] = '\0';
 583 +       else if (buffer[PAGE_SIZE-1])
 584 +               goto out;
 585 +
 586 +       err = -EINVAL;
 587 +       down(&debug_list_mutex);
 588 +
 589 +       if (strncmp("set", buffer, 3))
 590 +               goto out_up;
 591 +       s = buffer + 3;
 592 +       setting_str = strsep(&s, "=");
 593 +       if (s == NULL)
 594 +               goto out_up;
 595 +       setting_str = strstrip(setting_str);
 596 +       value_str = strsep(&s, " ");
 597 +       if (s == NULL)
 598 +               goto out_up;
 599 +       s = strstrip(s);
 600 +       if (!strncmp(s, "all", 3))
 601 +               all = 1;
 602 +       else
 603 +               elem = find_debug_module(s);
 604 +       if (!strncmp(setting_str, "enable", 6)) {
 605 +               value = !!simple_strtol(value_str, NULL, 10);
 606 +               if (all) {
 607 +                       if (value) {
 608 +                               set_all(true);
 609 +                               num_enabled = nr_entries;
 610 +                               dynamic_enabled = DYNAMIC_ENABLED_ALL;
 611 +                       } else {
 612 +                               set_all(false);
 613 +                               num_enabled = 0;
 614 +                               dynamic_enabled = DYNAMIC_ENABLED_NONE;
 615 +                       }
 616 +                       err = 0;
 617 +               } else {
 618 +                       if (elem) {
 619 +                               if (value && (elem->enable == 0)) {
 620 +                                       dynamic_printk_enabled |=
 621 +                                                       (1LL << elem->hash1);
 622 +                                       dynamic_printk_enabled2 |=
 623 +                                                       (1LL << elem->hash2);
 624 +                                       elem->enable = 1;
 625 +                                       num_enabled++;
 626 +                                       dynamic_enabled = DYNAMIC_ENABLED_SOME;
 627 +                                       err = 0;
 628 +                                       printk(KERN_DEBUG
 629 +                                              "debugging enabled for module %s",
 630 +                                              elem->name);
 631 +                               } else if (!value && (elem->enable == 1)) {
 632 +                                       elem->enable = 0;
 633 +                                       num_enabled--;
 634 +                                       if (disabled_hash(elem->hash1, true))
 635 +                                               dynamic_printk_enabled &=
 636 +                                                       ~(1LL << elem->hash1);
 637 +                                       if (disabled_hash(elem->hash2, false))
 638 +                                               dynamic_printk_enabled2 &=
 639 +                                                       ~(1LL << elem->hash2);
 640 +                                       if (num_enabled)
 641 +                                               dynamic_enabled =
 642 +                                                       DYNAMIC_ENABLED_SOME;
 643 +                                       else
 644 +                                               dynamic_enabled =
 645 +                                                       DYNAMIC_ENABLED_NONE;
 646 +                                       err = 0;
 647 +                                       printk(KERN_DEBUG
 648 +                                              "debugging disabled for module "
 649 +                                              "%s", elem->name);
 650 +                               }
 651 +                       }
 652 +               }
 653 +       }
 654 +       if (!err)
 655 +               err = length;
 656 +out_up:
 657 +       up(&debug_list_mutex);
 658 +out:
 659 +       free_page((unsigned long)buffer);
 660 +       return err;
 661 +}
 662 +
 663 +static void *pr_debug_seq_start(struct seq_file *f, loff_t *pos)
 664 +{
 665 +       return (*pos < DEBUG_HASH_TABLE_SIZE) ? pos : NULL;
 666 +}
 667 +
 668 +static void *pr_debug_seq_next(struct seq_file *s, void *v, loff_t *pos)
 669 +{
 670 +       (*pos)++;
 671 +       if (*pos >= DEBUG_HASH_TABLE_SIZE)
 672 +               return NULL;
 673 +       return pos;
 674 +}
 675 +
 676 +static void pr_debug_seq_stop(struct seq_file *s, void *v)
 677 +{
 678 +       /* Nothing to do */
 679 +}
 680 +
 681 +static int pr_debug_seq_show(struct seq_file *s, void *v)
 682 +{
 683 +       struct hlist_head *head;
 684 +       struct hlist_node *node;
 685 +       struct debug_name *elem;
 686 +       unsigned int i = *(loff_t *) v;
 687 +
 688 +       rcu_read_lock();
 689 +       head = &module_table[i];
 690 +       hlist_for_each_entry_rcu(elem, node, head, hlist) {
 691 +               seq_printf(s, "%s enabled=%d", elem->name, elem->enable);
 692 +               seq_printf(s, "\n");
 693 +       }
 694 +       rcu_read_unlock();
 695 +       return 0;
 696 +}
 697 +
 698 +static struct seq_operations pr_debug_seq_ops = {
 699 +       .start = pr_debug_seq_start,
 700 +       .next  = pr_debug_seq_next,
 701 +       .stop  = pr_debug_seq_stop,
 702 +       .show  = pr_debug_seq_show
 703 +};
 704 +
 705 +static int pr_debug_open(struct inode *inode, struct file *filp)
 706 +{
 707 +       return seq_open(filp, &pr_debug_seq_ops);
 708 +}
 709 +
 710 +static const struct file_operations pr_debug_operations = {
 711 +       .open           = pr_debug_open,
 712 +       .read           = seq_read,
 713 +       .write          = pr_debug_write,
 714 +       .llseek         = seq_lseek,
 715 +       .release        = seq_release,
 716 +};
 717 +
 718 +static int __init dynamic_printk_init(void)
 719 +{
 720 +       struct dentry *dir, *file;
 721 +       struct mod_debug *iter;
 722 +       unsigned long value;
 723 +
 724 +       dir = debugfs_create_dir("dynamic_printk", NULL);
 725 +       if (!dir)
 726 +               return -ENOMEM;
 727 +       file = debugfs_create_file("modules", 0644, dir, NULL,
 728 +                                       &pr_debug_operations);
 729 +       if (!file) {
 730 +               debugfs_remove(dir);
 731 +               return -ENOMEM;
 732 +       }
 733 +       for (value = (unsigned long)__start___verbose;
 734 +               value < (unsigned long)__stop___verbose;
 735 +               value += sizeof(struct mod_debug)) {
 736 +                       iter = (struct mod_debug *)value;
 737 +                       register_dynamic_debug_module(iter->modname,
 738 +                               iter->type,
 739 +                               iter->logical_modname,
 740 +                               iter->flag_names, iter->hash, iter->hash2);
 741 +       }
 742 +       return 0;
 743 +}
 744 +module_init(dynamic_printk_init);
 745 +/* may want to move this earlier so we can get traces as early as possible */
 746 +
 747 +static int __init dynamic_printk_setup(char *str)
 748 +{
 749 +       if (str)
 750 +               return -ENOENT;
 751 +       set_all(true);
 752 +       return 0;
 753 +}
 754 +/* Use early_param(), so we can get debug output as early as possible */
 755 +early_param("dynamic_printk", dynamic_printk_setup);
 756 --- a/lib/Kconfig.debug
 757 +++ b/lib/Kconfig.debug
 758 @@ -752,6 +752,61 @@ menuconfig BUILD_DOCSRC
 759
 760           Say N if you are unsure.
 761
 762 +config DYNAMIC_PRINTK_DEBUG
 763 +       bool "Enable dynamic printk() call support"
 764 +       default n
 765 +       depends on PRINTK
 766 +       select PRINTK_DEBUG
 767 +       help
 768 +
 769 +         Compiles debug level messages into the kernel, which would not
 770 +         otherwise be available at runtime. These messages can then be
 771 +         enabled/disabled on a per module basis. This mechanism implicitly
 772 +         enables all pr_debug() and dev_dbg() calls. The impact of this
 773 +         compile option is a larger kernel text size of about 2%.
 774 +
 775 +         Usage:
 776 +
 777 +         Dynamic debugging is controlled by the debugfs file,
 778 +         dynamic_printk/modules. This file contains a list of the modules that
 779 +         can be enabled. The format of the file is the module name, followed
 780 +         by a set of flags that can be enabled. The first flag is always the
 781 +         'enabled' flag. For example:
 782 +
 783 +               <module_name> <enabled=0/1>
 784 +                               .
 785 +                               .
 786 +                               .
 787 +
 788 +         <module_name> : Name of the module in which the debug call resides
 789 +         <enabled=0/1> : whether the messages are enabled or not
 790 +
 791 +         From a live system:
 792 +
 793 +               snd_hda_intel enabled=0
 794 +               fixup enabled=0
 795 +               driver enabled=0
 796 +
 797 +         Enable a module:
 798 +
 799 +               $echo "set enabled=1 <module_name>" > dynamic_printk/modules
 800 +
 801 +         Disable a module:
 802 +
 803 +               $echo "set enabled=0 <module_name>" > dynamic_printk/modules
 804 +
 805 +         Enable all modules:
 806 +
 807 +               $echo "set enabled=1 all" > dynamic_printk/modules
 808 +
 809 +         Disable all modules:
 810 +
 811 +               $echo "set enabled=0 all" > dynamic_printk/modules
 812 +
 813 +         Finally, passing "dynamic_printk" at the command line enables
 814 +         debugging for all modules. This mode can be turned off via the above
 815 +         disable command.
 816 +
 817  source "samples/Kconfig"
 818
 819  source "lib/Kconfig.kgdb"
 820 --- a/lib/Makefile
 821 +++ b/lib/Makefile
 822 @@ -81,6 +81,8 @@ obj-$(CONFIG_HAVE_LMB) += lmb.o
 823
 824  obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o
 825
 826 +obj-$(CONFIG_DYNAMIC_PRINTK_DEBUG) += dynamic_printk.o
 827 +
 828  hostprogs-y    := gen_crc32table
 829  clean-files    := crc32table.h
 830
 831 --- a/net/netfilter/nf_conntrack_pptp.c
 832 +++ b/net/netfilter/nf_conntrack_pptp.c
 833 @@ -65,7 +65,7 @@ void
 834                              struct nf_conntrack_expect *exp) __read_mostly;
 835  EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn);
 836
 837 -#ifdef DEBUG
 838 +#if defined(DEBUG) || defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
 839  /* PptpControlMessageType names */
 840  const char *const pptp_msg_name[] = {
 841         "UNKNOWN_MESSAGE",
 842 --- /dev/null
 843 +++ b/scripts/basic/hash.c
 844 @@ -0,0 +1,64 @@
 845 +/*
 846 + * Copyright (C) 2008 Red Hat, Inc., Jason Baron <jbaron@redhat.com>
 847 + *
 848 + */
 849 +
 850 +#include <stdio.h>
 851 +#include <stdlib.h>
 852 +#include <string.h>
 853 +
 854 +#define DYNAMIC_DEBUG_HASH_BITS 6
 855 +
 856 +static const char *program;
 857 +
 858 +static void usage(void)
 859 +{
 860 +       printf("Usage: %s <djb2|r5> <modname>\n", program);
 861 +       exit(1);
 862 +}
 863 +
 864 +/* djb2 hashing algorithm by Dan Bernstein. From:
 865 + * http://www.cse.yorku.ca/~oz/hash.html
 866 + */
 867 +
 868 +unsigned int djb2_hash(char *str)
 869 +{
 870 +       unsigned long hash = 5381;
 871 +       int c;
 872 +
 873 +       c = *str;
 874 +       while (c) {
 875 +               hash = ((hash << 5) + hash) + c;
 876 +               c = *++str;
 877 +       }
 878 +       return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
 879 +}
 880 +
 881 +unsigned int r5_hash(char *str)
 882 +{
 883 +       unsigned long hash = 0;
 884 +       int c;
 885 +
 886 +       c = *str;
 887 +       while (c) {
 888 +               hash = (hash + (c << 4) + (c >> 4)) * 11;
 889 +               c = *++str;
 890 +       }
 891 +       return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
 892 +}
 893 +
 894 +int main(int argc, char *argv[])
 895 +{
 896 +       program = argv[0];
 897 +
 898 +       if (argc != 3)
 899 +               usage();
 900 +       if (!strcmp(argv[1], "djb2"))
 901 +               printf("%d\n", djb2_hash(argv[2]));
 902 +       else if (!strcmp(argv[1], "r5"))
 903 +               printf("%d\n", r5_hash(argv[2]));
 904 +       else
 905 +               usage();
 906 +       exit(0);
 907 +}
 908 +
 909 --- a/scripts/basic/Makefile
 910 +++ b/scripts/basic/Makefile
 911 @@ -9,7 +9,7 @@
 912  # fixdep:       Used to generate dependency information during build process
 913  # docproc:      Used in Documentation/DocBook
 914
 915 -hostprogs-y    := fixdep docproc
 916 +hostprogs-y    := fixdep docproc hash
 917  always         := $(hostprogs-y)
 918
 919  # fixdep is needed to compile other host programs
 920 --- a/scripts/Makefile.lib
 921 +++ b/scripts/Makefile.lib
 922 @@ -96,6 +96,14 @@ basename_flags = -D"KBUILD_BASENAME=KBUI
 923  modname_flags  = $(if $(filter 1,$(words $(modname))),\
 924                   -D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")
 925
 926 +#hash values
 927 +ifdef CONFIG_DYNAMIC_PRINTK_DEBUG
 928 +debug_flags = -D"DEBUG_HASH=$(shell ./scripts/basic/hash djb2 $(@D)$(modname))"\
 929 +              -D"DEBUG_HASH2=$(shell ./scripts/basic/hash r5 $(@D)$(modname))"
 930 +else
 931 +debug_flags =
 932 +endif
 933 +
 934  orig_c_flags   = $(KBUILD_CFLAGS) $(ccflags-y) $(CFLAGS_$(basetarget).o)
 935  _c_flags       = $(filter-out $(CFLAGS_REMOVE_$(basetarget).o), $(orig_c_flags))
 936  _a_flags       = $(KBUILD_AFLAGS) $(asflags-y) $(AFLAGS_$(basetarget).o)
 937 @@ -121,7 +129,8 @@ endif
 938
 939  c_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) \
 940                  $(__c_flags) $(modkern_cflags) \
 941 -                -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags)
 942 +                -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags) \
 943 +                 $(debug_flags)
 944
 945  a_flags        = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) \
 946                  $(__a_flags) $(modkern_aflags)