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>
diff --git a/kernel/module.c b/kernel/module.c
index d5fcd24..c527006 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -784,6 +784,7 @@
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 @@
}
#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 @@
#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 @@
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 @@
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;