[PATCH v5 2/9] moduleparam: add data member to struct kernel_param

From: Jim Cromie
Date: Fri Aug 13 2021 - 11:25:51 EST


Add a const 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,
and latter is redefined to use former.

It calls __module_param_call_wdata(), which accepts a new data param
and inits .data with it. Re-define __module_param_call() to use it.

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

---
v4+:
. const void* data - <emil.l.velikov@xxxxxxxxx>

Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
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..878387e0b2d9 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;
};
+ const 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