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]) by smtp.lore.kernel.org (Postfix) with ESMTP id B27BCC5321D for ; Thu, 22 Aug 2024 19:49:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 120B28005F; Thu, 22 Aug 2024 15:49:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0D3048005A; Thu, 22 Aug 2024 15:49:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E8BB28005F; Thu, 22 Aug 2024 15:49:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id CB5568005A for ; Thu, 22 Aug 2024 15:49:02 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 3C185A9524 for ; Thu, 22 Aug 2024 19:49:02 +0000 (UTC) X-FDA: 82480919724.24.22D3580 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf17.hostedemail.com (Postfix) with ESMTP id 75A5540008 for ; Thu, 22 Aug 2024 19:49:00 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=QjFr4vdm; spf=pass (imf17.hostedemail.com: domain of broonie@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=broonie@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=1724356123; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=RvFOOUnu4LQCvVJhY48Se4BiLc7KJi8eMP4KE2AZcfk=; b=WfaDZ9MHkIdkfkf6SCc4NNbxY9Gij9+rLICkyB+EmWrU0RwejyD/hiQPW+63hhGD8LfKSH ajXGg63lKEHAFhZrG640pxQkvUDKaOrRIkcMXED0i7RyZ9p4g/1xMbezjZz83/K2MWzqkq wtv1LkEwWWMJm/Zn1+uvPZVIvJR8mkw= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=QjFr4vdm; spf=pass (imf17.hostedemail.com: domain of broonie@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=broonie@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1724356123; a=rsa-sha256; cv=none; b=Pa6XLyvIn5YBVVFZ2HGrwy2b1sljyFivdwbne18RWeQJLLoVy1uAHEVv+EfpjPuiVn/Tha LI6NvWFOzOfiHz7NmMssG8HqRHuA7wpge1+CkXNLNIODOHhlj3l6+Zc60YZ05NKLvObHiF NiUUgn/wdL7X5TI9qz7X5qfyP+xeInY= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 6231861199; Thu, 22 Aug 2024 19:48:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97675C32782; Thu, 22 Aug 2024 19:48:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724356139; bh=vHrYYwpLYrMdWCxNwu9b7Dbs6lQkJVhNyl0BaU6kaqY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QjFr4vdmuguovWr4xstpV8xF58Pq4jPc8qo0rDXbMkPwNwi/Mtjfj7iPgvESHqIf/ 0Vu3uk+CHl7dkhCPmdQwf9rDaB3rt9zi56N25TflW89xjirvRVH+9bmEE3cPnVfM8A 1ycLXEQFqVHm8XpKomSwSy2eWKKupfqLQqnYoX3k4ZUbvgtbd7KlgPs+5my4YdLJ1F Gu2oqt82Qzl29Y896EhXUW0zDcXd9LTkL+Qyrq5Td/80vpFHbkRG0bADmOmrfxDdqe 6XjmxgUu7aGgbErPP34636gRbvizmYXf1yHFQGHdr2fxw1ucuoMtOPzT1c9FbdG8Do XVfahtHXMi++Q== Date: Thu, 22 Aug 2024 20:48:56 +0100 From: Mark Brown To: Matthew Wilcox Cc: "Liam R. Howlett" , Cristian Ciocaltea , maple-tree@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/5] maple_tree: Allow external locks to be configured with their map Message-ID: References: <20240822-b4-regmap-maple-nolock-v1-0-d5e6dbae3396@kernel.org> <20240822-b4-regmap-maple-nolock-v1-1-d5e6dbae3396@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="4fxvcd//gcNS1l/S" Content-Disposition: inline In-Reply-To: X-Cookie: Your love life will be... interesting. X-Rspam-User: X-Stat-Signature: ot8rfw54y768647ekyyh1fsioi3t57na X-Rspamd-Queue-Id: 75A5540008 X-Rspamd-Server: rspam11 X-HE-Tag: 1724356140-51725 X-HE-Meta: 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 e05bC6Ae JzcpWIxzwS7QYk16w33ylfLGuMBLAjgl+pGerk4BSV7lBHZsAn9pcdWtS3KS7oghoDr4n+mVPzDX6gKt3cEOl9VkVTvVdlxLcDbtjdrDKzU3ezqxb8oAZvPqcb2UfidDivJ+W2/06MVBEArxTZYbOgd+S0wdjJw43kTPinfOK/kD5/VhPorkNjqwldmaF3BiZJoYqWQH+A+dU9GDgxSiUlRafOvYEKeMIkDilTx+Fv0eBX2KjGhFupfWzOpet4z33Btw6xs0g7dI9+Sj8WVQ5aIJnzFx/Juljhlxqps/pXlgGM9P/cnC7mqVvoRaGU3qHPJdoBhz6NT19lrM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000441, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --4fxvcd//gcNS1l/S Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Aug 22, 2024 at 08:21:40PM +0100, Matthew Wilcox wrote: > On Thu, Aug 22, 2024 at 08:13:35PM +0100, Mark Brown wrote: > > Currently the maple tree code allows external locks to be configured by > > passing the lock itself. This is generally helpful and convenient but is > No, it's a really bad idea. Stop doing it. Use the internal lock. > It's a temporary hack we put in and I'm really regretting allowing it. I mean, we do use the internal lock here since otherwise lockdep moans but it's pure overhead which just complicates the code. It's only ever taken within another lock, meaning it winds up protecting nothing for these maple trees. We can't go the other way round and use the maple tree lock as the regmap lock since apart from anything else it's a spin lock and we need to use a mutex most of the time to support busses that sleep during I/O. --4fxvcd//gcNS1l/S Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmbHliAACgkQJNaLcl1U h9BGLQf+KaHwyNa3gCljDUOtxigUv0bPCPgmuFaZzITTLKm0YvnpxqQJIOWokFq9 7+bmG3fdtxffPVO/BceSbfQkMbW8Gjkbh0TWCD3VmZBQ3UMiIiU0LF9/Vnv1ZAlG dnRCUtXzULqlDHCHNBoaQgDV0L0xB3+RmAxEWtfny1gTqaN+BO1yP6s1nPD+qBos 9qa71AYCM7lSjObStWccEqct9gLC08gDwIFknroF7YGRIk8/eRRzr4AA/61LkZEK UDMEODc7+qeDCBnUp7/U2GFvYmss6+1axzeKEi+GRjMoi2ds8wUv2DDCorSeY1aX CFWA7G++3W4VraKYnaQKNl1qG2OIzA== =RNbC -----END PGP SIGNATURE----- --4fxvcd//gcNS1l/S--