core_param() for genuinely core kernel parameters
PATCH 3/5 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 Rusty Russell <[email protected]>
--- include/linux/moduleparam.h | 19 +++++++++++++++++++ kernel/params.c | 14 +++++++------- 2 files changed, 26 insertions(+), 7 deletions(-)
include/linux/moduleparam.h +19 -0
@@ -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
@@ -637,14 +637,14 @@ static void __init param_sysfs_builtin(v 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); } }