From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 04CAACA0EED for ; Fri, 22 Aug 2025 11:05:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4C2AB280019; Fri, 22 Aug 2025 07:05:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 49A658E009D; Fri, 22 Aug 2025 07:05:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3B053280019; Fri, 22 Aug 2025 07:05:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 26D748E009D for ; Fri, 22 Aug 2025 07:05:33 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id CC2CEC010D for ; Fri, 22 Aug 2025 11:05:32 +0000 (UTC) X-FDA: 83804112504.11.34CC235 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf16.hostedemail.com (Postfix) with ESMTP id 35FCF18000C for ; Fri, 22 Aug 2025 11:05:31 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=GIfvdYlb; spf=pass (imf16.hostedemail.com: domain of dakr@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=dakr@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1755860731; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=sBceu6QfC9/WWC1L8u9ha80WVRD+kekazvacogRY4E4=; b=X+nnlgHraAwHf+F/Jm96Ex4Bo0WsgnwAPqgiZyWMfLtXyDR7LKyESZeOg37qzjz68wDAYt DxjncOcZGZYkjqWGl5uJlyZd3r3liCgeYqIiusLzbUriPLUnxfs57aXijJT6p06mUc57Of N29NNd9Hq4i2WsR/u03iZbiEiBqnFKU= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1755860731; a=rsa-sha256; cv=none; b=VtD0CCOCOUMbySZ+Zn7xwbu91ELszjG1Q7AxFER4hitatANqDkzk+tXRH3Vb5ElJ1V/q+z e0gp2swBhOKl4nGxfgdQvo9s4LElqXLkHh1zgFX0lYK1kpffF6bXOKXM8+F1/SDQLJ6gHX cRzVygnSRHt+VM1tJ12CFO21Kez5yOc= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=GIfvdYlb; spf=pass (imf16.hostedemail.com: domain of dakr@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=dakr@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 25EBA5C6EF0; Fri, 22 Aug 2025 11:05:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE74DC4CEED; Fri, 22 Aug 2025 11:05:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755860729; bh=WJf6g5RzafPQV91L2VIgFZn7ZVuqRfgK1tvm7SBza24=; h=Date:To:From:Subject:Cc:References:In-Reply-To:From; b=GIfvdYlbRH5IIFq4bXFlt6CRdt01QKOGW3IwCR8DvTJ8Gy1V6y3W8SwFRHPCm7/bu XvY3Ttkh6vYbxe6aNuvh34/KpCA1QMKEsYr/fiO5u04KF0hoeYcZ69JCyC7JzPESJO SA3fG0IlQytBFERdE3qkky6Wrb7BCT24vUBsLIPn2cTD6tLVZHXebQ8Ht7/C8ydCxl dk1Qp4MFSRFBeBBjBcpDJVsqsoRXoY+17Kvh3wTvYZVECYXsZsWhKxWRiXb7vSCuUm xMQWvzbrpwdxtc5fqFDJVZRo4W1hhI9xLLp6wR+1K2LLlm4K0SNCB8dEnritsbedY5 dJxOiy/FxxcMg== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 22 Aug 2025 13:05:25 +0200 Message-Id: To: "Miguel Ojeda" From: "Danilo Krummrich" Subject: Re: [PATCH v2 2/5] rust: maple_tree: add MapleTree Cc: "Alice Ryhl" , "Andrew Morton" , "Liam R. Howlett" , "Lorenzo Stoakes" , "Miguel Ojeda" , "Andrew Ballance" , "Boqun Feng" , "Gary Guo" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Trevor Gross" , , , , References: <20250819-maple-tree-v2-0-229b48657bab@google.com> <20250819-maple-tree-v2-2-229b48657bab@google.com> In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 35FCF18000C X-Stat-Signature: oozswx1mpdcezpxpprs6onejyshn5w94 X-HE-Tag: 1755860731-734074 X-HE-Meta: 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 3KEOZh+I WjYJlgc/vq8ve6ioM4OS+8pKJeuMYh0K6h5cZvUU20RqV0YYEaiTnNjhW0VpSV/JGbTOj3Flt9yflBZaWf3sLkW5R/5HFv2tgPBb57UfWBvDEJD/4sMEVhbp2AFjwmhRCsoduckhOUStp31SOeoDVL/CvaOIxRaINqHEFIExBczC9RYevpFvsV7Q0qkcTlJ8YZTU6dntYDDFZsF9iZAK3/H9GK9TNQYBhNOMvMh4SPRgj0hDnjewe/EFvAR+UumxKYHPuzvvggNLZm3cRKjjpBsrSYRDv+KqggiPglN/BLwadn5PlPRx/bAho20qeNlIoOEMidE0ZTws6svQKwylezYAIfxUq2xezo6D+oHFGGIeRvLnGRun2hP601bRK9WcFX8rFvoGq/g6XSxZ7ZRiALHxhYi35rTjDQuMjcDsGqZo0BncFoSwCEFDJeQpdkuXEXSUSPSMOU+CCd3fXG0uy0hL5j8l6Je4LXG0cMlECvykiw4E= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri Aug 22, 2025 at 3:40 AM CEST, Miguel Ojeda wrote: > So, as a rule of thumb, probably we don't want to show `unwrap()`s in > examples if the code could have been written "properly" instead I think we never want to use unwrap(). Even in cases where we relly want to panic the kernel (because we reached a point where otherwise it is impossib= le to prevent undefined behavior) we should make the panic() explicit. I see it fairly often in reviews that an unwrap() sneaked its way into the = code for things that can easily be handled gracefully, such as simple range chec= ks, etc. We should probably check if we can get a clippy warning in place for this. > , but > `unwrap_err()`s (i.e. error ones) within an `assert!` are likely fine > if the example would be better with it. I agree, for obvious reasons unwrap_err() is much less of a concern. Yet, it might be read as a pointer in the wrong direction, i.e. read as "un= wraps are OK". If we want to check for a specific error type (or cause) in doc-tests I thi= nk we should just use is_err_and() instead. For instance, instead of assert_eq!( tree.insert(100, the_answer, GFP_KERNEL).unwrap_err().cause, InsertErrorKind::Occupied, ); we could also write assert!(tree .insert(100, the_answer, GFP_KERNEL) .is_err_and(|e| e.cause =3D=3D InsertErrorKind::Occupied)); which is exactly the pattern also shown in the example of is_err_and() [1] = and entirely avoid any unwrap() calls. [1] https://doc.rust-lang.org/std/result/enum.Result.html#method.is_err_and