From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f176.google.com (mail-yw1-f176.google.com [209.85.128.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1AA9B329C43 for ; Mon, 10 Nov 2025 15:09:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762787398; cv=none; b=S7PMrl1BwMrYQQlYQCCQ1U2WXitNaZJKOkn72blPGQ6cvomM4pKHjyN3+0Rt4g2Y6pRTePQpw6pKwvTJVOkT2wBwwzX+VPQBCMLrk7oxeOoPtZcJV42pPD+AGK9VQY9+kCE52wzIVa4CB2xjbqxop6zqqLb9VGJxHIPcF9NfQmE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762787398; c=relaxed/simple; bh=Rj9G8IFEjlzisLHEn/O9WORrl+0cZLi6zlkht4lv9Mg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=HgDaQvGLGdf+cLBA+Qb/WSK5PG28eNQccIYe9roYfgbxayFZW5JR9Kx1zUNsauNRpgKIaCO3yRZU7YPiWSLM6Nd+rYDvU4OdtvNdb0G4/hc2tR3ACEwOllwCKkM+EBVhf8l4ojOoJzPyJfc0PAjhezrN9r1+cw6tCu9juyN3CzI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=d+3I4qJu; arc=none smtp.client-ip=209.85.128.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="d+3I4qJu" Received: by mail-yw1-f176.google.com with SMTP id 00721157ae682-78665368a5cso28871097b3.3 for ; Mon, 10 Nov 2025 07:09:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1762787395; x=1763392195; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=KbWyUnaltl9mde3lXFQpujvquSvJb+LnnWGVBKXm7v0=; b=d+3I4qJuPpBCju+7Ga5lk1Mav2ICwuVB+UMEIssiIsD+SOCMAESN+JpjQQ1AxUi2Xc H2viDCx6fMXUb8WGaKsUzHqto4/S9yMLpR1VKWWjEw6bbyxbe9W1P7s0vipwzk1ua291 Q8y+i1mxx1Y4bHuphNYNtUfDZ9SqbIaZjGw/gAWWQAd3Cl3ioLoLfwhNun8u08ZYGQjN iJelm/oXPQGDUYw8K4wy8jjayaKlNzJmQ6r95H75BjIV6yxaiV42iPTqvd/pdhQ5Ujpc qRIK+SYlVLkKPVFC1UCWUmh0neq+3x7gm36OE6SO3wJKCIiAgXwZReX6xNhgfNj6p7If /0vw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762787395; x=1763392195; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=KbWyUnaltl9mde3lXFQpujvquSvJb+LnnWGVBKXm7v0=; b=IvlBexCBVH3GcLthNtQyVtdd/cMvZO09OaaZinaSDiXsohuK6NWbBK81OKH12H5BrF D8aylOHQamoZf/Zxkk8c6cps+PxaBmkcKXTHuDz2p+9DLN/wgMn+ZsU2V6dw+nqYEE65 XxRFrW0u1csO2F+c8EVJIHYmx68BzCq30+OJqwuhbxkKfgit4ZlqD6KGqM8M5miAUvCO Vi3TMAw7xpIYPbQGdb2KIeStpRUZ/sqkIHCvzKvo4IoXtlDqsmd7bcSl63XnREsPgk2B zuK4G+krpnCpTp1D1OCp+bxlTSMQoxUsgDit5bx/+Pqvcn8I9dexEY0a+nAbQ5IvXZWK 2JNQ== X-Forwarded-Encrypted: i=1; AJvYcCVzvDoPAzauasRzcefF08r42Byguc2SG59eeQbS0Y27eeTJGyO/waj5TwaEDivEzP0QtRwYKygXeLhJJdA=@vger.kernel.org X-Gm-Message-State: AOJu0Yw4EC6fs3W8hf2aOdhbjvC9t+Gnfp4IPDO2RnfC1P6t9vUxOFFv LkR09s4gL61raDuiojpVQTp7HjnhBNMxsmWxf4TOfHOxkJhUkJc80cHM X-Gm-Gg: ASbGnct0RXkHdoUPvAC7OiKy++Gk7h8zw102ulGvK9pKk6zIoIvCI/s4i4Y8KSzi9ia heFkDJbkINSXeouR0I/18vhJPIuw7+8ar/Z2l5rvYoN4DIoX4LbJY6W/gUnSclwi8DTkbfVt4Kj P0fia1Z3NTAgW/iORu270zM8OJvbMm/AkRTNc9YuOmD+/ngx8sIZAwpe/gyj3y5dHY/AkTSKLrk J9JjxrKCSLwZE9wFS3G4xJDF5J6yRNAdiolXdOdur+tLbjBTnOlfUzDSZ1NKEqtirmEE3E4IZWW HMFhNotz4p5aUUdDedWPBRLgqV/nXdweSa2wGMX5n+1jLrvmwebIbJqlCQWqPBGGjETesAfjTAu UZcCqNqYes1a7+QeIagEOovZAG27dZxyuyLWMQnuzkSfhW62YnLb14mrAbC8aInoPK38P2MWxQ/ BH8/OjuPiS1hgJMs/Njz766X/ZD7L5n9as X-Google-Smtp-Source: AGHT+IFrAjrniG9BqJ1S9xPDXhNH4sZLvzscceoEFbHM4PmfHq9Xxx41lhZiVBUQ/FUix83x+tNDww== X-Received: by 2002:a05:690e:d47:b0:640:e6aa:b2bf with SMTP id 956f58d0204a3-640e6aab4e1mr3921691d50.43.1762787395046; Mon, 10 Nov 2025 07:09:55 -0800 (PST) Received: from localhost (c-73-105-0-253.hsd1.fl.comcast.net. [73.105.0.253]) by smtp.gmail.com with ESMTPSA id 00721157ae682-787d69ba646sm23716177b3.30.2025.11.10.07.09.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Nov 2025 07:09:54 -0800 (PST) Date: Mon, 10 Nov 2025 10:09:53 -0500 From: Yury Norov To: Alice Ryhl Cc: Tamir Duberstein , Greg Kroah-Hartman , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , Carlos Llamas , Suren Baghdasaryan , Burak Emir , Miguel Ojeda , Boqun Feng , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Trevor Gross , Danilo Krummrich , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 1/6] rust: bitmap: add MAX_LEN and NO_ALLOC_MAX_LEN constants Message-ID: References: <20251110-binder-bitmap-v4-0-5ed8a7fab1b9@google.com> <20251110-binder-bitmap-v4-1-5ed8a7fab1b9@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Nov 10, 2025 at 10:01:32AM -0500, Yury Norov wrote: > On Mon, Nov 10, 2025 at 02:20:17PM +0000, Alice Ryhl wrote: > > On Mon, Nov 10, 2025 at 08:59:36AM -0500, Tamir Duberstein wrote: > > > On Mon, Nov 10, 2025 at 8:06 AM Alice Ryhl wrote: > > > > > > > > To avoid hard-coding these values in drivers, define constants for them > > > > that drivers can reference. > > > > > > > > Acked-by: Danilo Krummrich > > > > Reviewed-by: Burak Emir > > > > Signed-off-by: Alice Ryhl > > > > --- > > > > rust/kernel/bitmap.rs | 16 +++++++++++----- > > > > 1 file changed, 11 insertions(+), 5 deletions(-) > > > > > > > > diff --git a/rust/kernel/bitmap.rs b/rust/kernel/bitmap.rs > > > > index aa8fc7bf06fc99865ae755d8694e4bec3dc8e7f0..15fa23b45054b9272415fcc000e3e3b52c74d7c1 100644 > > > > --- a/rust/kernel/bitmap.rs > > > > +++ b/rust/kernel/bitmap.rs > > > > @@ -149,14 +149,14 @@ macro_rules! bitmap_assert_return { > > > > /// > > > > /// # Invariants > > > > /// > > > > -/// * `nbits` is `<= i32::MAX` and never changes. > > > > +/// * `nbits` is `<= MAX_LEN`. > > > > /// * if `nbits <= bindings::BITS_PER_LONG`, then `repr` is a `usize`. > > > > > > Should this and other references to bindings::BITS_PER_LONG be > > > `NO_ALLOC_MAX_LEN` instead? > > > > Ah yeah it probably makes sense to update this in a bunch of places. > > Yes, please. > > NO_ALLOC sounds a bit weird in exported API. Maybe NBITS_INPLACE > or similar? You add a 'new_inline()' constructor in this series, so this parameter should be LEN_INLINE or NBITS_INLINE, like that. > Also, at this point we're really close to: > > pub const NBITS_INPLACE: usize = CONFIG_NBITS_INPLACE; > > union BitmapRepr { > bitmap: [usize, BITS_TO_LONGS(NBITS_INPLACE)] > ptr: NonNull, > } > > That would be a very useful addition for some particular scenarios, > I believe. Even if you don't want to make it configurable, let's > keep this option in mind? > > Thanks, > Yury