rust: uaccess: use INLINE_COPY_TO_USER to guard copy_to_user()

Patch series "uaccess: unify inline vs outline copy_{from,to}_user()
selection", v2.

The kernel allows arches to select between inline and outline
implementations of the copy_{from,to}_user() by defining individual
INLINE_COPY_FROM_USER and INLINE_COPY_TO_USER, correspondingly.  However,
all arches enable or disable them always together.

Without the real use-case for one helper being inlined while the other
outlined, having independent controls is excessive and error prone.

The first patch of the series fixes rust/uaccess coppy_to_user() wrapper
guarded with INLINE_COPY_FROM_USER.  The 2nd patch switches codebase to
the unified INLINE_COPY_USER.  And the last patch cleans up ifdefery in
the include/linux/uaccess.h

This patch (of 3):

The copy_to_user() rust helper is only needed when the main kernel inlines
the function.  It is controlled by INLINE_COPY_TO_USER, but the rust
helper is protected with INLINE_COPY_FROM_USER.

Fix that.

Link: https://lore.kernel.org/20260425020857.356850-1-ynorov@nvidia.com
Link: https://lore.kernel.org/20260425020857.356850-2-ynorov@nvidia.com
Fixes: d99dc586ca7c7 ("uaccess: decouple INLINE_COPY_FROM_USER and CONFIG_RUST")
Signed-off-by: Yury Norov <ynorov@nvidia.com>
Reported-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Closes: https://lore.kernel.org/all/746c9c50-20c4-4dc9-a539-bf1310ff9414@kernel.org/
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Viktor Malik <vmalik@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/rust/helpers/uaccess.c b/rust/helpers/uaccess.c
index d9625b9ee04669777e01af05034af35218557050..aff22f16ab3884199cb1478b4069f0181ab218a7 100644 (file)
--- a/rust/helpers/uaccess.c
+++ b/rust/helpers/uaccess.c
@@ -20,7 +20,9 @@ unsigned long rust_helper__copy_from_user(void *to, const void __user *from, uns
 {
        return _inline_copy_from_user(to, from, n);
 }
+#endif
 
+#ifdef INLINE_COPY_TO_USER
 __rust_helper
 unsigned long rust_helper__copy_to_user(void __user *to, const void *from, unsigned long n)
 {