Re: [PATCH v2 2/2] drm/tyr: allow userspace buffers to be mismatched

[Alice Ryhl <aliceryhl@google.com>]

On Thu, Oct 15, 2026 at 11:35:21AM -0700, Deborah Brouwer wrote:
> +// If the user buffer is at least the minimum required size, then
> +// copy as much of the kernel object as will fit into the user buffer.
> +// Don't fail if the user buffer is smaller than the kernel object.
> +// If the user buffer is bigger than needed, zero out the remainder.
> +fn set_uobj<T: AsBytes>(usr_dst: u64, size: u32, min_size: usize, src_obj: &T) -> Result {
> +    if (size as usize) < min_size {
> +        return Err(EINVAL);

Use `kernel::num::casts::u32_as_usize` here.

> +    }
> +
> +    let mut writer = UserSlice::new(UserPtr::from_addr(usr_dst as usize), size as usize).writer();

Avoid casting to usize twice.

	let size = kernel::num::casts::u32_as_usize(size);

Alice