linux/scripts/basic/hash.c

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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>
2008-08-12 20:46:19 +00:00
/*
* Copyright (C) 2008 Red Hat, Inc., Jason Baron <jbaron@redhat.com>
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define DYNAMIC_DEBUG_HASH_BITS 6
static const char *program;
static void usage(void)
{
printf("Usage: %s <djb2|r5> <modname>\n", program);
exit(1);
}
/* djb2 hashing algorithm by Dan Bernstein. From:
* http://www.cse.yorku.ca/~oz/hash.html
*/
unsigned int djb2_hash(char *str)
{
unsigned long hash = 5381;
int c;
c = *str;
while (c) {
hash = ((hash << 5) + hash) + c;
c = *++str;
}
return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
}
unsigned int r5_hash(char *str)
{
unsigned long hash = 0;
int c;
c = *str;
while (c) {
hash = (hash + (c << 4) + (c >> 4)) * 11;
c = *++str;
}
return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
}
int main(int argc, char *argv[])
{
program = argv[0];
if (argc != 3)
usage();
if (!strcmp(argv[1], "djb2"))
printf("%d\n", djb2_hash(argv[2]));
else if (!strcmp(argv[1], "r5"))
printf("%d\n", r5_hash(argv[2]));
else
usage();
exit(0);
}