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core_param() for genuinely core kernel parameters

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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: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2008-10-22 10:00:23 -05:00
parent 9b473de872
commit 67e67ceaac
2 changed files with 26 additions and 7 deletions
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19
include/linux/moduleparam.h
View file

@ -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 \

14
kernel/params.c
View file

@ -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);
}
}