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346e15beb5
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>
65 lines
1.1 KiB
C
65 lines
1.1 KiB
C
/*
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* Copyright (C) 2008 Red Hat, Inc., Jason Baron <jbaron@redhat.com>
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define DYNAMIC_DEBUG_HASH_BITS 6
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static const char *program;
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static void usage(void)
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{
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printf("Usage: %s <djb2|r5> <modname>\n", program);
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exit(1);
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}
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/* djb2 hashing algorithm by Dan Bernstein. From:
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* http://www.cse.yorku.ca/~oz/hash.html
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*/
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unsigned int djb2_hash(char *str)
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{
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unsigned long hash = 5381;
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int c;
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c = *str;
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while (c) {
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hash = ((hash << 5) + hash) + c;
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c = *++str;
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}
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return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
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}
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unsigned int r5_hash(char *str)
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{
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unsigned long hash = 0;
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int c;
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c = *str;
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while (c) {
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hash = (hash + (c << 4) + (c >> 4)) * 11;
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c = *++str;
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}
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return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
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}
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int main(int argc, char *argv[])
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{
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program = argv[0];
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if (argc != 3)
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usage();
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if (!strcmp(argv[1], "djb2"))
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printf("%d\n", djb2_hash(argv[2]));
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else if (!strcmp(argv[1], "r5"))
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printf("%d\n", r5_hash(argv[2]));
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else
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usage();
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exit(0);
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}
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