Now that we've got the same knob selecting inline vs outline copy_to_user()
and copy_from_user(), we can simplify the corresponding logic in the
uaccess.h.

Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
 include/linux/uaccess.h | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 0ddd2806d7f5..19079588c78c 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -190,10 +190,6 @@ _inline_copy_from_user(void *to, const void __user *from, unsigned long n)
 	memset(to + (n - res), 0, res);
 	return res;
 }
-#ifndef INLINE_COPY_USER
-extern __must_check unsigned long
-_copy_from_user(void *, const void __user *, unsigned long);
-#endif
 
 static inline __must_check unsigned long
 _inline_copy_to_user(void __user *to, const void *from, unsigned long n)
@@ -207,7 +203,13 @@ _inline_copy_to_user(void __user *to, const void *from, unsigned long n)
 	}
 	return n;
 }
-#ifndef INLINE_COPY_USER
+#ifdef INLINE_COPY_USER
+# define _copy_to_user _inline_copy_to_user
+# define _copy_from_user _inline_copy_from_user
+#else
+extern __must_check unsigned long
+_copy_from_user(void *, const void __user *, unsigned long);
+
 extern __must_check unsigned long
 _copy_to_user(void __user *, const void *, unsigned long);
 #endif
@@ -217,11 +219,8 @@ copy_from_user(void *to, const void __user *from, unsigned long n)
 {
 	if (!check_copy_size(to, n, false))
 		return n;
-#ifdef INLINE_COPY_USER
-	return _inline_copy_from_user(to, from, n);
-#else
+
 	return _copy_from_user(to, from, n);
-#endif
 }
 
 static __always_inline unsigned long __must_check
@@ -230,11 +229,7 @@ copy_to_user(void __user *to, const void *from, unsigned long n)
 	if (!check_copy_size(from, n, true))
 		return n;
 
-#ifdef INLINE_COPY_USER
-	return _inline_copy_to_user(to, from, n);
-#else
 	return _copy_to_user(to, from, n);
-#endif
 }
 
 #ifndef copy_mc_to_kernel
-- 
2.43.0

Le 25/03/2026 à 17:33, Yury Norov a écrit :
> Now that we've got the same knob selecting inline vs outline copy_to_user()
> and copy_from_user(), we can simplify the corresponding logic in the
> uaccess.h.

I think we should get rid of ifdefery completly, see below. And with 
comment to previous patch,

     __is_defined(INLINE_COPY_TO_USER)

becomes

     !IS_ENABLED(CONFIG_ARCH_WANT_OUTLINE_USER_COPY)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 327f967a24b8..02a05dd61a77 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -190,10 +190,9 @@ _inline_copy_from_user(void *to, const void __user 
*from, unsigned long n)
  	memset(to + (n - res), 0, res);
  	return res;
  }
-#ifndef INLINE_COPY_FROM_USER
+
  extern __must_check unsigned long
  _copy_from_user(void *, const void __user *, unsigned long);
-#endif

  static inline __must_check unsigned long
  _inline_copy_to_user(void __user *to, const void *from, unsigned long n)
@@ -207,21 +206,19 @@ _inline_copy_to_user(void __user *to, const void 
*from, unsigned long n)
  	}
  	return n;
  }
-#ifndef INLINE_COPY_TO_USER
+
  extern __must_check unsigned long
  _copy_to_user(void __user *, const void *, unsigned long);
-#endif

  static __always_inline unsigned long __must_check
  copy_from_user_common(void *to, const void __user *from, unsigned long 
n, bool partial)
  {
  	if (!check_copy_size(to, n, false))
  		return n;
-#ifdef INLINE_COPY_FROM_USER
-	return _inline_copy_from_user(to, from, n);
-#else
-	return _copy_from_user(to, from, n);
-#endif
+	if (__is_defined(INLINE_COPY_FROM_USER))
+		return _inline_copy_from_user(to, from, n);
+	else
+		return _copy_from_user(to, from, n);
  }

  static __always_inline unsigned long __must_check
@@ -242,11 +239,10 @@ copy_to_user_common(void __user *to, const void 
*from, unsigned long n, bool par
  	if (!check_copy_size(from, n, true))
  		return n;

-#ifdef INLINE_COPY_TO_USER
-	return _inline_copy_to_user(to, from, n);
-#else
-	return _copy_to_user(to, from, n);
-#endif
+	if (__is_defined(INLINE_COPY_TO_USER))
+		return _inline_copy_to_user(to, from, n);
+	else
+		return _copy_to_user(to, from, n);
  }

  static __always_inline unsigned long __must_check


Christophe

On Wed, Mar 25, 2026 at 12:33:12PM -0400, Yury Norov wrote:
> Now that we've got the same knob selecting inline vs outline copy_to_user()
> and copy_from_user(), we can simplify the corresponding logic in the
> uaccess.h.
> 
> Signed-off-by: Yury Norov <ynorov@nvidia.com>

Both patches are:
Tested-by: Alice Ryhl <aliceryhl@google.com>

But I can't help but think if it wouldn't be slightly better to split up
the first patch in a targeted Fixes: path that just fixes the FROM/TO
mixup, and a follow-up non-fix that actually deduplicates the two
ifdefs.

> @@ -217,11 +219,8 @@ copy_from_user(void *to, const void __user *from, unsigned long n)
>  {
>  	if (!check_copy_size(to, n, false))
>  		return n;
> -#ifdef INLINE_COPY_USER
> -	return _inline_copy_from_user(to, from, n);
> -#else
> +
>  	return _copy_from_user(to, from, n);
> -#endif

Spurious extra empty line here?

Alice