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driver core: basic infrastructure for per-module dynamic debug messages

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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>
This commit is contained in:
Jason Baron
2008-08-12 16:46:19 -04:00
committed by Greg Kroah-Hartman
parent 33376c1c04
commit 346e15beb5
14 changed files with 700 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
kernel/module.c
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@@ -784,6 +784,7 @@ sys_delete_module(const char __user *name_user, unsigned int flags)
mutex_lock(&module_mutex);
/* Store the name of the last unloaded module for diagnostic purposes */
strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));
unregister_dynamic_debug_module(mod->name);
free_module(mod);
out:
@@ -1783,6 +1784,33 @@ static inline void add_kallsyms(struct module *mod,
}
#endif /* CONFIG_KALLSYMS */
#ifdef CONFIG_DYNAMIC_PRINTK_DEBUG
static void dynamic_printk_setup(Elf_Shdr *sechdrs, unsigned int verboseindex)
{
struct mod_debug *debug_info;
unsigned long pos, end;
unsigned int num_verbose;
pos = sechdrs[verboseindex].sh_addr;
num_verbose = sechdrs[verboseindex].sh_size /
sizeof(struct mod_debug);
end = pos + (num_verbose * sizeof(struct mod_debug));
for (; pos < end; pos += sizeof(struct mod_debug)) {
debug_info = (struct mod_debug *)pos;
register_dynamic_debug_module(debug_info->modname,
debug_info->type, debug_info->logical_modname,
debug_info->flag_names, debug_info->hash,
debug_info->hash2);
}
}
#else
static inline void dynamic_printk_setup(Elf_Shdr *sechdrs,
unsigned int verboseindex)
{
}
#endif /* CONFIG_DYNAMIC_PRINTK_DEBUG */
static void *module_alloc_update_bounds(unsigned long size)
{
void *ret = module_alloc(size);
@@ -1831,6 +1859,7 @@ static noinline struct module *load_module(void __user *umod,
#endif
unsigned int markersindex;
unsigned int markersstringsindex;
unsigned int verboseindex;
struct module *mod;
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
@@ -2117,6 +2146,7 @@ static noinline struct module *load_module(void __user *umod,
markersindex = find_sec(hdr, sechdrs, secstrings, "__markers");
markersstringsindex = find_sec(hdr, sechdrs, secstrings,
"__markers_strings");
verboseindex = find_sec(hdr, sechdrs, secstrings, "__verbose");
/* Now do relocations. */
for (i = 1; i < hdr->e_shnum; i++) {
@@ -2167,6 +2197,7 @@ static noinline struct module *load_module(void __user *umod,
marker_update_probe_range(mod->markers,
mod->markers + mod->num_markers);
#endif
dynamic_printk_setup(sechdrs, verboseindex);
err = module_finalize(hdr, sechdrs, mod);
if (err < 0)
goto cleanup;