modules: extend initcall_debug functionality to the module loader

The kernel has this really nice facility where if you put "initcall_debug"
on the kernel commandline, it'll print which function it's going to
execute just before calling an initcall, and then after the call completes
it will

1) print if it had an error code

2) checks for a few simple bugs (like leaving irqs off)
and

3) print how long the init call took in milliseconds.

While trying to optimize the boot speed of my laptop, I have been loving
number 3 to figure out what to optimize...  ...  and then I wished that
the same thing was done for module loading.

This patch makes the module loader use this exact same functionality; it's
a logical extension in my view (since modules are just sort of late
binding initcalls anyway) and so far I've found it quite useful in finding
where things are too slow in my boot.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

include/linux/init.h

@@ -139,6 +139,7 @@ extern initcall_t __con_initcall_start[], __con_initcall_end[];
 extern initcall_t __security_initcall_start[], __security_initcall_end[];
 
 /* Defined in init/main.c */
+extern int do_one_initcall(initcall_t fn);
 extern char __initdata boot_command_line[];
 extern char *saved_command_line;
 extern unsigned int reset_devices;

init/main.c

@@ -691,7 +691,7 @@ asmlinkage void __init start_kernel(void)
 	rest_init();
 }
 
-static int __initdata initcall_debug;
+static int initcall_debug;
 
 static int __init initcall_debug_setup(char *str)
 {
@@ -700,7 +700,7 @@ static int __init initcall_debug_setup(char *str)
 }
 __setup("initcall_debug", initcall_debug_setup);
 
-static void __init do_one_initcall(initcall_t fn)
+int do_one_initcall(initcall_t fn)
 {
 	int count = preempt_count();
 	ktime_t t0, t1, delta;
@@ -740,6 +740,8 @@ static void __init do_one_initcall(initcall_t fn)
 		print_fn_descriptor_symbol(KERN_WARNING "initcall %s", fn);
 		printk(" returned with %s\n", msgbuf);
 	}
+
+	return result;
 }
 
 

kernel/module.c

@@ -2288,7 +2288,7 @@ sys_init_module(void __user *umod,
 
 	/* Start the module */
 	if (mod->init != NULL)
-		ret = mod->init();
+		ret = do_one_initcall(mod->init);
 	if (ret < 0) {
 		/* Init routine failed: abort.  Try to protect us from
                    buggy refcounters. */