Commit 67e67cea authored by Rusty Russell's avatar Rusty Russell
Browse files

core_param() for genuinely core kernel parameters 



There are a lot of one-liner uses of __setup() in the kernel: they're
cumbersome and not queryable (definitely not settable) via /sys.  Yet
it's ugly to simplify them to module_param(), because by default that
inserts a prefix of the module name (usually filename).

So, introduce a "core_param".  The parameter gets no prefix, but
appears in /sys/module/kernel/parameters/ (if non-zero perms arg).  I
thought about using the name "core", but that's more common than
"kernel".  And if you create a module called "kernel", you will die
a horrible death.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 9b473de8

include/linux/moduleparam.h

+19 −0
Original line number Diff line number Diff line
@@ -104,6 +104,25 @@ struct kparam_array 
#define module_param(name, type, perm)				\

	module_param_named(name, name, type, perm)



#ifndef MODULE

/**

 * core_param - define a historical core kernel parameter.

 * @name: the name of the cmdline and sysfs parameter (often the same as var)

 * @var: the variable

 * @type: the type (for param_set_##type and param_get_##type)

 * @perm: visibility in sysfs

 *

 * core_param is just like module_param(), but cannot be modular and

 * doesn't add a prefix (such as "printk.").  This is for compatibility

 * with __setup(), and it makes sense as truly core parameters aren't

 * tied to the particular file they're in.

 */

#define core_param(name, var, type, perm)				\

	param_check_##type(name, &(var));				\

	__module_param_call("", name, param_set_##type, param_get_##type, \

			    &var, perm)

#endif /* !MODULE */



/* Actually copy string: maxlen param is usually sizeof(string). */

#define module_param_string(name, string, len, perm)			\

	static const struct kparam_string __param_string_##name		\

kernel/params.c

+7 −7
Original line number Diff line number Diff line
@@ -637,14 +637,14 @@ static void __init param_sysfs_builtin(void) 


		dot = strchr(kp->name, '.');

		if (!dot) {

			DEBUGP("couldn't find period in first %d characters "

			       "of %s\n", MODULE_NAME_LEN, kp->name);

			continue;

			/* This happens for core_param() */

			strcpy(modname, "kernel");

			name_len = 0;

		} else {

			name_len = dot - kp->name + 1;

			strlcpy(modname, kp->name, name_len);

		}

		name_len = dot - kp->name;

		strncpy(modname, kp->name, name_len);

		modname[name_len] = '\0';

		kernel_add_sysfs_param(modname, kp, name_len+1);

		kernel_add_sysfs_param(modname, kp, name_len);

	}

}

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