From 68aabb29a5469e4b7358e70e64a7fac433e27f06 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Mon, 5 Jan 2026 14:25:03 +0000 Subject: rust: redefine `bindings::compat_ptr_ioctl` in Rust There is currently an inconsistency between C and Rust, which is that when Rust requires cfg(CONFIG_COMPAT) on compat_ioctl when using the compat_ptr_ioctl symbol because '#define compat_ptr_ioctl NULL' does not get translated to anything by bindgen. But it's not *just* a matter of translating the '#define' into Rust when CONFIG_COMPAT=n. This is because when CONFIG_COMPAT=y, the type of compat_ptr_ioctl is a non-nullable function pointer, and to seamlessly use it regardless of the config, we need a nullable function pointer. I think it's important to do something about this; I've seen the mistake of accidentally forgetting '#[cfg(CONFIG_COMPAT)]' when compat_ptr_ioctl is used multiple times now. This explicitly declares 'bindings::compat_ptr_ioctl' as an Option that is always defined but might be None. This matches C, but isn't ideal: it modifies the bindings crate. But I'm not sure if there's a better way to do it. If we just redefine in kernel/, then people may still use the one in bindings::, since that is where you would normally find it. I am open to suggestions. Signed-off-by: Alice Ryhl Reviewed-by: Gary Guo Link: https://patch.msgid.link/20260105-redefine-compat_ptr_ioctl-v1-1-25edb3d91acc@google.com Signed-off-by: Greg Kroah-Hartman --- rust/kernel/miscdevice.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel/miscdevice.rs') diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs index ba64c8a858f0..c3c2052c9206 100644 --- a/rust/kernel/miscdevice.rs +++ b/rust/kernel/miscdevice.rs @@ -410,7 +410,7 @@ impl MiscdeviceVTable { compat_ioctl: if T::HAS_COMPAT_IOCTL { Some(Self::compat_ioctl) } else if T::HAS_IOCTL { - Some(bindings::compat_ptr_ioctl) + bindings::compat_ptr_ioctl } else { None }, -- cgit v1.2.3