2021-07-31 21:43:51

by Jim Cromie

Subject: [PATCH v4 2/7] moduleparam: add data member to struct kernel_param

Add a void* data member to the struct, to allow attaching private data
that will be used soon by a setter method (via kp->data) to perform
more elaborate actions.

To attach the data at compile time, add new macros:
module_param_cbd() derives from module_param_cb(), adding data param.
It calls __module_param_call_wdata(), which has accepts new data
param and inits .data with it. Re-define __module_param_call() using it.

Use of this new data member will be rare, it might be worth redoing
this as a separate/sub-type to keep the base case.

Signed-off-by: Jim Cromie <[email protected]>
---
include/linux/moduleparam.h | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index eed280fae433..e9495b1e794d 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -78,6 +78,7 @@ struct kernel_param {
const struct kparam_string *str;
const struct kparam_array *arr;
};
+ void *data;
};

extern const struct kernel_param __start___param[], __stop___param[];
@@ -175,6 +176,9 @@ struct kparam_array
#define module_param_cb(name, ops, arg, perm) \
__module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1, 0)

+#define module_param_cbd(name, ops, arg, perm, data) \
+ __module_param_call_wdata(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1, 0, data)
+
#define module_param_cb_unsafe(name, ops, arg, perm) \
__module_param_call(MODULE_PARAM_PREFIX, name, ops, arg, perm, -1, \
KERNEL_PARAM_FL_UNSAFE)
@@ -284,14 +288,17 @@ struct kparam_array

/* This is the fundamental function for registering boot/module
parameters. */
-#define __module_param_call(prefix, name, ops, arg, perm, level, flags) \
+#define __module_param_call(prefix, name, ops, arg, perm, level, flags) \
+ __module_param_call_wdata(prefix, name, ops, arg, perm, level, flags, NULL)
+
+#define __module_param_call_wdata(prefix, name, ops, arg, perm, level, flags, data) \
/* Default value instead of permissions? */ \
static const char __param_str_##name[] = prefix #name; \
static struct kernel_param __moduleparam_const __param_##name \
__used __section("__param") \
__aligned(__alignof__(struct kernel_param)) \
= { __param_str_##name, THIS_MODULE, ops, \
- VERIFY_OCTAL_PERMISSIONS(perm), level, flags, { arg } }
+ VERIFY_OCTAL_PERMISSIONS(perm), level, flags, { arg }, data }

/* Obsolete - use module_param_cb() */
#define module_param_call(name, _set, _get, arg, perm) \
--
2.31.1

2021-08-02 16:21:14

by Emil Velikov

Subject: Re: [PATCH v4 2/7] moduleparam: add data member to struct kernel_param

Hi Jim,

On Sat, 31 Jul 2021 at 22:42, Jim Cromie <[email protected]> wrote:

> Use of this new data member will be rare, it might be worth redoing
> this as a separate/sub-type to keep the base case.
>
> Signed-off-by: Jim Cromie <[email protected]>
> ---
> include/linux/moduleparam.h | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
> index eed280fae433..e9495b1e794d 100644
> --- a/include/linux/moduleparam.h
> +++ b/include/linux/moduleparam.h
> @@ -78,6 +78,7 @@ struct kernel_param {
> const struct kparam_string *str;
> const struct kparam_array *arr;
> };
> + void *data;

Might as well make this "const void *" since it is a compile-time constant?

-Emil

2021-08-02 18:38:05

by Jim Cromie

Subject: Re: [PATCH v4 2/7] moduleparam: add data member to struct kernel_param

On Mon, Aug 2, 2021 at 10:18 AM Emil Velikov <[email protected]> wrote:
>
> Hi Jim,
>
> On Sat, 31 Jul 2021 at 22:42, Jim Cromie <[email protected]> wrote:
>
> > Use of this new data member will be rare, it might be worth redoing
> > this as a separate/sub-type to keep the base case.
> >
> > Signed-off-by: Jim Cromie <[email protected]>
> > ---
> > include/linux/moduleparam.h | 11 +++++++++--
> > 1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
> > index eed280fae433..e9495b1e794d 100644
> > --- a/include/linux/moduleparam.h
> > +++ b/include/linux/moduleparam.h
> > @@ -78,6 +78,7 @@ struct kernel_param {
> > const struct kparam_string *str;
> > const struct kparam_array *arr;
> > };
> > + void *data;
>
> Might as well make this "const void *" since it is a compile-time constant?
>

yes indeed. revising. thanks

> -Emil