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 seem to not need memory (kmalloc) set up yet.
If it is possible to move initialization even before __setup boot
parameter processing, the temporary variable to copy away the boot paramter
and later use it in dynamic_debug_init() is not needed anymore.
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 <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: [email protected]
---
lib/dynamic_debug.c | 33 +++++++++++++++++++++++----------
1 file changed, 23 insertions(+), 10 deletions(-)
Index: linux-2.6.34-master/lib/dynamic_debug.c
===================================================================
--- linux-2.6.34-master.orig/lib/dynamic_debug.c
+++ linux-2.6.34-master/lib/dynamic_debug.c
@@ -748,13 +748,14 @@ static void ddebug_remove_all_tables(voi
mutex_unlock(&ddebug_lock);
}
-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(voi
debugfs_remove(dir);
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(voi
}
out_free:
- if (ret) {
+ if (ret)
ddebug_remove_all_tables();
- debugfs_remove(dir);
- debugfs_remove(file);
- }
+ else
+ ddebug_init_success = 1;
return 0;
}
-module_init(dynamic_debug_init);
+/* Allow early initialization for boot messages via boot param */
+arch_initcall(dynamic_debug_init);
+/* Debugfs setup must be done later */
+module_init(dynamic_debug_init_debugfs);