kernel-ark/include/linux/dynamic_printk.h
Jason Baron 346e15beb5 driver core: basic infrastructure for per-module dynamic debug messages
Base infrastructure to enable per-module debug messages.

I've introduced CONFIG_DYNAMIC_PRINTK_DEBUG, which when enabled centralizes
control of debugging statements on a per-module basis in one /proc file,
currently, <debugfs>/dynamic_printk/modules. When, CONFIG_DYNAMIC_PRINTK_DEBUG,
is not set, debugging statements can still be enabled as before, often by
defining 'DEBUG' for the proper compilation unit. Thus, this patch set has no
affect when CONFIG_DYNAMIC_PRINTK_DEBUG is not set.

The infrastructure currently ties into all pr_debug() and dev_dbg() calls. That
is, if CONFIG_DYNAMIC_PRINTK_DEBUG is set, all pr_debug() and dev_dbg() calls
can be dynamically enabled/disabled on a per-module basis.

Future plans include extending this functionality to subsystems, that define 
their own debug levels and flags.

Usage:

Dynamic debugging is controlled by the debugfs file, 
<debugfs>/dynamic_printk/modules. This file contains a list of the modules that
can be enabled. The format of the file is as follows:

	<module_name> <enabled=0/1>
		.
		.
		.

	<module_name> : Name of the module in which the debug call resides
	<enabled=0/1> : whether the messages are enabled or not

For example:

	snd_hda_intel enabled=0
	fixup enabled=1
	driver enabled=0

Enable a module:

	$echo "set enabled=1 <module_name>" > dynamic_printk/modules

Disable a module:

	$echo "set enabled=0 <module_name>" > dynamic_printk/modules

Enable all modules:

	$echo "set enabled=1 all" > dynamic_printk/modules

Disable all modules:

	$echo "set enabled=0 all" > dynamic_printk/modules

Finally, passing "dynamic_printk" at the command line enables
debugging for all modules. This mode can be turned off via the above
disable command.

[gkh: minor cleanups and tweaks to make the build work quietly]

Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-10-16 09:24:47 -07:00

94 lines
2.9 KiB
C

#ifndef _DYNAMIC_PRINTK_H
#define _DYNAMIC_PRINTK_H
#define DYNAMIC_DEBUG_HASH_BITS 6
#define DEBUG_HASH_TABLE_SIZE (1 << DYNAMIC_DEBUG_HASH_BITS)
#define TYPE_BOOLEAN 1
#define DYNAMIC_ENABLED_ALL 0
#define DYNAMIC_ENABLED_NONE 1
#define DYNAMIC_ENABLED_SOME 2
extern int dynamic_enabled;
/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
* bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
* use independent hash functions, to reduce the chance of false positives.
*/
extern long long dynamic_printk_enabled;
extern long long dynamic_printk_enabled2;
struct mod_debug {
char *modname;
char *logical_modname;
char *flag_names;
int type;
int hash;
int hash2;
} __attribute__((aligned(8)));
int register_dynamic_debug_module(char *mod_name, int type, char *share_name,
char *flags, int hash, int hash2);
#if defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
extern int unregister_dynamic_debug_module(char *mod_name);
extern int __dynamic_dbg_enabled_helper(char *modname, int type,
int value, int hash);
#define __dynamic_dbg_enabled(module, type, value, level, hash) ({ \
int __ret = 0; \
if (unlikely((dynamic_printk_enabled & (1LL << DEBUG_HASH)) && \
(dynamic_printk_enabled2 & (1LL << DEBUG_HASH2)))) \
__ret = __dynamic_dbg_enabled_helper(module, type, \
value, hash);\
__ret; })
#define dynamic_pr_debug(fmt, ...) do { \
static char mod_name[] \
__attribute__((section("__verbose_strings"))) \
= KBUILD_MODNAME; \
static struct mod_debug descriptor \
__used \
__attribute__((section("__verbose"), aligned(8))) = \
{ mod_name, mod_name, NULL, TYPE_BOOLEAN, DEBUG_HASH, DEBUG_HASH2 };\
if (__dynamic_dbg_enabled(KBUILD_MODNAME, TYPE_BOOLEAN, \
0, 0, DEBUG_HASH)) \
printk(KERN_DEBUG KBUILD_MODNAME ":" fmt, \
##__VA_ARGS__); \
} while (0)
#define dynamic_dev_dbg(dev, format, ...) do { \
static char mod_name[] \
__attribute__((section("__verbose_strings"))) \
= KBUILD_MODNAME; \
static struct mod_debug descriptor \
__used \
__attribute__((section("__verbose"), aligned(8))) = \
{ mod_name, mod_name, NULL, TYPE_BOOLEAN, DEBUG_HASH, DEBUG_HASH2 };\
if (__dynamic_dbg_enabled(KBUILD_MODNAME, TYPE_BOOLEAN, \
0, 0, DEBUG_HASH)) \
dev_printk(KERN_DEBUG, dev, \
KBUILD_MODNAME ": " format, \
##__VA_ARGS__); \
} while (0)
#else
static inline int unregister_dynamic_debug_module(const char *mod_name)
{
return 0;
}
static inline int __dynamic_dbg_enabled_helper(char *modname, int type,
int value, int hash)
{
return 0;
}
#define __dynamic_dbg_enabled(module, type, value, level, hash) ({ 0; })
#define dynamic_pr_debug(fmt, ...) do { } while (0)
#define dynamic_dev_dbg(dev, format, ...) do { } while (0)
#endif
#endif