linux-kernel - [PATCH v2 11/11] sysctl: Create macro for user-to-kernel uint converter

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Message-Id: <20251016-jag-sysctl_conv-v2-11-a2f16529acc4@kernel.org>
Date: Thu, 16 Oct 2025 14:57:57 +0200
From: Joel Granados <joel.granados@...nel.org>
To: Alexander Viro <viro@...iv.linux.org.uk>, 
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
 Kees Cook <kees@...nel.org>, Joel Granados <joel.granados@...nel.org>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 11/11] sysctl: Create macro for user-to-kernel uint
 converter

Replace sysctl_user_to_kern_uint_conv function with
SYSCTL_USER_TO_KERN_UINT_CONV macro that accepts u_ptr_op parameter for
value transformation. Replacing sysctl_kern_to_user_uint_conv is not
needed as it will only be used from within sysctl.c. This is a
preparation commit for creating a custom converter in fs/pipe.c. No
Functional changes are intended.

Signed-off-by: Joel Granados <joel.granados@...nel.org>
---
 kernel/sysctl.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 750c94313c1fd23551e03f455585d2dd94f3c758..9b08573bbacdfa0ec036a8043561253c21300c9a 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -462,15 +462,19 @@ static SYSCTL_INT_CONV_CUSTOM(_ms_jiffies_minmax,
 			      sysctl_user_to_kern_int_conv_ms,
 			      sysctl_kern_to_user_int_conv_ms, true)
 
-static int sysctl_user_to_kern_uint_conv(const unsigned long *u_ptr,
-					 unsigned int *k_ptr)
-{
-	if (*u_ptr > UINT_MAX)
-		return -EINVAL;
-	WRITE_ONCE(*k_ptr, *u_ptr);
-	return 0;
+#define SYSCTL_USER_TO_KERN_UINT_CONV(name, u_ptr_op)		\
+int sysctl_user_to_kern_uint_conv##name(const unsigned long *u_ptr,\
+					unsigned int *k_ptr)	\
+{								\
+	unsigned long u = u_ptr_op(*u_ptr);			\
+	if (u > UINT_MAX)					\
+		return -EINVAL;					\
+	WRITE_ONCE(*k_ptr, u);					\
+	return 0;						\
 }
 
+static SYSCTL_USER_TO_KERN_UINT_CONV(, SYSCTL_CONV_IDENTITY)
+
 static int sysctl_kern_to_user_uint_conv(unsigned long *u_ptr,
 					 const unsigned int *k_ptr)
 {

-- 
2.50.1