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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 9846AC43603 for ; Fri, 20 Dec 2019 14:16:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6B4D6222C2 for ; Fri, 20 Dec 2019 14:16:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576851369; bh=ozdmvQULKSXokLNWdk7mYphvTDazwayXgBTn7Ekeph4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=bPhU8SFAYEAw9rTJTb7zYtYqHTu333wBSyKFzL6kF0KvNGm10IjDibSADo+Ihaope meYsKUvWWkzfyL07F7a1134nC4f37Xdteyn3+bR/ZrwOjoA8/PaRCJ/dPoR8VUsWYl ESlcPc6XamWekXS5GRKH/ZdscrlGmNJXB23i8VE0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727406AbfLTOQI (ORCPT ); Fri, 20 Dec 2019 09:16:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:58522 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727344AbfLTOQI (ORCPT ); Fri, 20 Dec 2019 09:16:08 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1C23021D7D; Fri, 20 Dec 2019 14:16:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576851367; bh=ozdmvQULKSXokLNWdk7mYphvTDazwayXgBTn7Ekeph4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rUYD7y0xQ0rgIYMrq8VaVZBlDMYXr2sK+cPuFusKHMyLPgsIlq/Ce/UpiwToV+sLN MiLXt8kUQfbwiwfhBBPQWfBw5Pp4ECdqFwvV4NuUZWGUF9+cQCmvCdKijw873h5uPO Kdt2zLejmQFIX21VRVEHX7Hmbw8zbkVd3WihSxvg= Date: Fri, 20 Dec 2019 15:16:05 +0100 From: Greg Kroah-Hartman To: Peter Zijlstra Cc: Marc Gonzalez , Rafael Wysocki , LKML , Linux ARM , Robin Murphy , Dmitry Torokhov , Alexey Brodkin , Will Deacon , Russell King , Bjorn Andersson , Tejun Heo , Mark Brown Subject: Re: [RFC PATCH v1] devres: align devres.data strictly only for devm_kmalloc() Message-ID: <20191220141605.GA2292734@kroah.com> References: <74ae22cd-08c1-d846-3e1d-cbc38db87442@free.fr> <20191220140655.GN2827@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191220140655.GN2827@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 20, 2019 at 03:06:55PM +0100, Peter Zijlstra wrote: > 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); > } > } > Ok, that's my queue to walk away from the keyboard and start drinking, I think the holiday season has now officially started. ugh. crazy. but brilliant :) greg k-h