linux-kernel - [PATCH 5/5] module: Rename MAX_PARAM_PREFIX_LEN to __MODULE_NAME

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Message-ID: <20250630143535.267745-6-petr.pavlu@suse.com>
Date: Mon, 30 Jun 2025 16:32:36 +0200
From: Petr Pavlu <petr.pavlu@...e.com>
To: Luis Chamberlain <mcgrof@...nel.org>,
	Petr Pavlu <petr.pavlu@...e.com>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Daniel Gomez <da.gomez@...sung.com>
Cc: linux-modules@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 5/5] module: Rename MAX_PARAM_PREFIX_LEN to __MODULE_NAME_LEN

The maximum module name length (MODULE_NAME_LEN) is somewhat confusingly
defined in terms of the maximum parameter prefix length
(MAX_PARAM_PREFIX_LEN), when in fact the dependency is in the opposite
direction.

This split originates from commit 730b69d22525 ("module: check kernel param
length at compile time, not runtime"). The code needed to use
MODULE_NAME_LEN in moduleparam.h, but because module.h requires
moduleparam.h, this created a circular dependency. It was resolved by
introducing MAX_PARAM_PREFIX_LEN in moduleparam.h and defining
MODULE_NAME_LEN in module.h in terms of MAX_PARAM_PREFIX_LEN.

Rename MAX_PARAM_PREFIX_LEN to __MODULE_NAME_LEN for clarity. This matches
the similar approach of defining MODULE_INFO in module.h and __MODULE_INFO
in moduleparam.h.

Signed-off-by: Petr Pavlu <petr.pavlu@...e.com>
---
 include/linux/module.h      |  2 +-
 include/linux/moduleparam.h | 12 ++++++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 5faa1fb1f4b4..0f1dde3996d9 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -32,7 +32,7 @@
 #include <linux/percpu.h>
 #include <asm/module.h>
 
-#define MODULE_NAME_LEN MAX_PARAM_PREFIX_LEN
+#define MODULE_NAME_LEN __MODULE_NAME_LEN
 
 struct modversion_info {
 	unsigned long crc;
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 110e9d09de24..a04a2bc4f51e 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -6,6 +6,13 @@
 #include <linux/stringify.h>
 #include <linux/kernel.h>
 
+/*
+ * The maximum module name length, including the NUL byte.
+ * Chosen so that structs with an unsigned long line up, specifically
+ * modversion_info.
+ */
+#define __MODULE_NAME_LEN (64 - sizeof(unsigned long))
+
 /* You can override this manually, but generally this should match the
    module name. */
 #ifdef MODULE
@@ -17,9 +24,6 @@
 #define __MODULE_INFO_PREFIX KBUILD_MODNAME "."
 #endif
 
-/* Chosen so that structs with an unsigned long line up. */
-#define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long))
-
 #define __MODULE_INFO(tag, name, info)					  \
 	static const char __UNIQUE_ID(name)[]				  \
 		__used __section(".modinfo") __aligned(1)		  \
@@ -284,7 +288,7 @@ struct kparam_array
 
 /* This is the fundamental function for registering boot/module parameters. */
 #define __module_param_call(prefix, name, ops, arg, perm, level, flags)	\
-	static_assert(sizeof(""prefix) - 1 <= MAX_PARAM_PREFIX_LEN);	\
+	static_assert(sizeof(""prefix) - 1 <= __MODULE_NAME_LEN);	\
 	static const char __param_str_##name[] = prefix #name;		\
 	static struct kernel_param __moduleparam_const __param_##name	\
 	__used __section("__param")					\
-- 
2.49.0