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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2CC5AC43603 for ; Fri, 20 Dec 2019 14:07:02 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EDF89206EC for ; Fri, 20 Dec 2019 14:07:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="mUMTkPP6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EDF89206EC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=c9qOvELUNGGkC1JFh9Sf3a6g0FQF+JLgPvkIjuTmiVA=; b=mUMTkPP6Gq6Ii1 AgPwsa71sa8wWlLZ1RUMxljNo5umhNbkQDrffHm4inwRqyBaROIy/BXdlDn0mQDxURmS9KKhcBavi GD2e8NI41nzf5HpkfubQ3I88A77mm/qC/VcGBecAbCcETnFkzpCH/wKZOOSoNwZJgI3a2zXSs5mVp W/B1FfZ/zq4zZ5y2NqexmHiEe7jdwRMunKhQQ1Ol5SUEeMtr4oQlT2Grywjfdgzd1UqLHnSamDh6O KfPK/4A7kXz0T1+JJJAGGRHP97Kt5bmDRoYT8H5IwftnsIOP7k7beQiNHRWqMcB4KDNDq5enKDgT3 6i8sQmNqiBXlSJdSLEtA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iiIvl-000143-C4; Fri, 20 Dec 2019 14:07:01 +0000 Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iiIvh-00013n-Ll; Fri, 20 Dec 2019 14:06:57 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 31F7130073C; Fri, 20 Dec 2019 15:05:31 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 23A21203A8993; Fri, 20 Dec 2019 15:06:55 +0100 (CET) Date: Fri, 20 Dec 2019 15:06:55 +0100 From: Peter Zijlstra To: Marc Gonzalez Subject: Re: [RFC PATCH v1] devres: align devres.data strictly only for devm_kmalloc() Message-ID: <20191220140655.GN2827@hirez.programming.kicks-ass.net> References: <74ae22cd-08c1-d846-3e1d-cbc38db87442@free.fr> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexey Brodkin , Will Deacon , Greg Kroah-Hartman , Dmitry Torokhov , Rafael Wysocki , LKML , Bjorn Andersson , Russell King , Mark Brown , Tejun Heo , Robin Murphy , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Dec 20, 2019 at 11:19:27AM +0100, Marc Gonzalez wrote: > Would anyone else have any suggestions, comments, insights, recommendations, > improvements, guidance, or wisdom? :-) Flip devres upside down! **WARNING, wear protective glasses when reading the below** struct devres { struct devres_node node; void *data; }; /* * We place struct devres at the tail of the memory allocation * such that data retains the ARCH_KMALLOC_MINALIGN alignment. * struct devres itself is just 4 pointers and should therefore * only require trivial alignment. */ static inline struct devres *data2devres(void *data) { return (struct devres *)(data + ksize(data) - sizeof(struct devres)); } void *alloc_dr(...) { struct devres *dr; void *data; data = kmalloc(size + sizeof(struct devres), GFP_KERNEL); dr = data2devres(data); WARN_ON((unsigned long)dr & __alignof(*dr)-1); INIT_LIST_HEAD(&dr->node.entry); dr->node.release = release; dr->data = data; return dr; } void devres_free(void *data) { if (data) { struct devres *dr = data2devres(data); BUG_ON(!list_empty(dr->node.entry)); kfree(data); } } static int release_nodes(...) { ... list_for_each_entry_safe_reverse(dr, ...) { ... kfree(dr->data); } } _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel