diff options
authorThomas Renninger <trenn@suse.de>2010-08-06 16:11:03 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2010-10-22 10:16:42 -0700
commit6a5c083de2f5fbf89a4b0a251be2c2205434d7ea (patch)
parenta648ec05bb950fae2f35d0490ddd6cf15010af72 (diff)
Dynamic Debug: Initialize dynamic debug earlier via arch_initcall
Having the ddebug_query= boot parameter it makes sense to set up dynamic debug as soon as possible. I expect sysfs files cannot be set up via an arch_initcall, because this one is even before fs_initcall. Therefore I splitted the dynamic_debug_init function into an early one and a later one providing /sys/../dynamic_debug/control file. Possibly dynamic_debug can be initialized even earlier, not sure whether this still makes sense then. I picked up arch_initcall as it covers quite a lot already. Dynamic debug needs to allocate memory, therefore it's not easily possible to set it up even before the command line gets parsed. Therefore the boot param query string is stored in a temp string which is applied when dynamic debug gets set up. This has been tested with ddebug_query="file ec.c +p" and I could retrieve pr_debug() messages early at boot during ACPI setup: ACPI: EC: Look up EC in DSDT ACPI: EC: ---> status = 0x08 ACPI: EC: transaction start ACPI: EC: <--- command = 0x80 ACPI: EC: ~~~> interrupt ACPI: EC: ---> status = 0x08 ACPI: EC: <--- data = 0xa4 ... ACPI: Interpreter enabled ACPI: (supports S0 S3 S4 S5) ACPI: Using IOAPIC for interrupt routing ACPI: EC: ---> status = 0x00 ACPI: EC: transaction start ACPI: EC: <--- command = 0x80 Signed-off-by: Thomas Renninger <trenn@suse.de> Acked-by: jbaron@redhat.com Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> CC: linux-acpi@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
1 files changed, 23 insertions, 10 deletions
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 44ce66bdb21..a687d902daa 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -748,13 +748,14 @@ static void ddebug_remove_all_tables(void)
-static int __init dynamic_debug_init(void)
+static __initdata int ddebug_init_success;
+static int __init dynamic_debug_init_debugfs(void)
struct dentry *dir, *file;
- struct _ddebug *iter, *iter_start;
- const char *modname = NULL;
- int ret = 0;
- int n = 0;
+ if (!ddebug_init_success)
+ return -ENODEV;
dir = debugfs_create_dir("dynamic_debug", NULL);
if (!dir)
@@ -765,6 +766,16 @@ static int __init dynamic_debug_init(void)
return -ENOMEM;
+ return 0;
+static int __init dynamic_debug_init(void)
+ struct _ddebug *iter, *iter_start;
+ const char *modname = NULL;
+ int ret = 0;
+ int n = 0;
if (__start___verbose != __stop___verbose) {
iter = __start___verbose;
modname = iter->modname;
@@ -795,11 +806,13 @@ static int __init dynamic_debug_init(void)
- if (ret) {
+ if (ret)
- debugfs_remove(dir);
- debugfs_remove(file);
- }
+ else
+ ddebug_init_success = 1;
return 0;
+/* Allow early initialization for boot messages via boot param */
+/* Debugfs setup must be done later */