linux-kernel - [PATCH v6 01/11] moduleparam: add data member to struct kernel

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Message-Id: <20210822222009.2035788-2-jim.cromie@gmail.com>
Date:   Sun, 22 Aug 2021 16:19:59 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     jbaron@...mai.com, gregkh@...uxfoundation.org,
        seanpaul@...omium.org, jeyu@...nel.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        amd-gfx@...ts.freedesktop.org, intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org
Cc:     Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v6 01/11] moduleparam: add data member to struct kernel_param

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_cb_data() derives from module_param_cb(), adding data
param, and latter is redefined to use former.

It calls __module_param_call_with_data(), which accepts 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.

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
v6:
. const void* data - <emil.l.velikov@...il.com>
. better macro names s/_cbd/_cb_data/, s/_wdata/_with_data/
. more const, no cast - Willy
---
 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..b8871e514de5 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_cb_data(name, ops, arg, perm, data)			\
+	__module_param_call_with_data(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_with_data(prefix, name, ops, arg, perm, level, flags, NULL)
+
+#define __module_param_call_with_data(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