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From: Andreas Hindborg <a.hindborg@kernel.org>
To: Alice Ryhl <aliceryhl@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>, Jens Axboe <axboe@kernel.dk>, Miguel
 Ojeda <ojeda@kernel.org>, Gary Guo <gary@garyguo.net>, =?utf-8?Q?Bj=C3=B6?=
 =?utf-8?Q?rn?= Roy Baron
 <bjorn3_gh@protonmail.com>, Benno Lossin <lossin@kernel.org>, Trevor Gross
 <tmgross@umich.edu>, Danilo Krummrich <dakr@kernel.org>, FUJITA Tomonori
 <fujita.tomonori@gmail.com>, Frederic Weisbecker <frederic@kernel.org>,
 Lyude Paul <lyude@redhat.com>, Thomas Gleixner <tglx@kernel.org>,
 Anna-Maria Behnsen <anna-maria@linutronix.de>, John Stultz
 <jstultz@google.com>, Stephen Boyd <sboyd@kernel.org>, Lorenzo Stoakes
 <lorenzo.stoakes@oracle.com>, "Liam R. Howlett" <Liam.Howlett@oracle.com>,
 linux-block@vger.kernel.org, rust-for-linux@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 28/79] block: rnull: add partial I/O support for bad blocks
In-Reply-To: <abf0FHWkQzbnOtqD@google.com>
References: <20260216-rnull-v6-19-rc5-send-v1-0-de9a7af4b469@kernel.org>
 <20260216-rnull-v6-19-rc5-send-v1-28-de9a7af4b469@kernel.org>
 <abf0FHWkQzbnOtqD@google.com>
Date: Wed, 03 Jun 2026 11:44:19 +0200
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Alice Ryhl <aliceryhl@google.com> writes:

> On Mon, Feb 16, 2026 at 12:35:15AM +0100, Andreas Hindborg wrote:

<cut>

>> +fn is_power_of_two<T>(value: T) -> bool
>> +where
>> +    T: core::ops::Sub<T, Output = T>,
>> +    T: core::ops::BitAnd<Output = T>,
>> +    T: core::cmp::PartialOrd<T>,
>> +    T: Copy,
>> +    T: From<u8>,
>> +{
>> +    (value > 0u8.into()) && (value & (value - 1u8.into())) == 0u8.into()
>> +}
>
> This is in the standard library.

But there is no trait for this, the method is defined for concrete
integer types. I would still need to define a trait and macro implement
it for all integers.

We could do this in `kernel::num`?


Best regards,
Andreas Hindborg