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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B329C00145 for ; Mon, 12 Dec 2022 14:14:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232266AbiLLOOn (ORCPT ); Mon, 12 Dec 2022 09:14:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40604 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232209AbiLLOOi (ORCPT ); Mon, 12 Dec 2022 09:14:38 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84F76E0C4; Mon, 12 Dec 2022 06:14:36 -0800 (PST) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1670854474; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3VulB7zwTi0kemDdT1n64bpcErOOyRtll4L59c0fe90=; b=Kn2lcmYIxBVg4IIOPGSEGR/k1rxrXoI40fjq0Mi2Af8Pp1ZBkKGS0qXDP7lb+ypjzICgjp BEMtPaWgChGoZ89Aba7lMQePQSt0WnUDc8IvQiH/AD1K5sfCdM8L/Eol5/B8QnLgWSJvoj /xW6F9PbvVWykvvmZyQodCP/6fvIesyCPlLxNJ/SVDsdLThZSC2nawycWD64o6eZeovNAe lhEe6qcaPh+wsW8YvD2sTbHCqDoruRb2gGeWCbbwiNaF0geQ46HlVlp6frMAXKekQrsMlV lqWx7Bmj/vI4+mnvODASw7w2fHApB3XlXEhaj1ysKhU1AYeYwh8gPYeY69Hxog== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1670854474; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3VulB7zwTi0kemDdT1n64bpcErOOyRtll4L59c0fe90=; b=pEiYiypPCSz/2tWa+00h65aYJ3NOBXSMcRJNGIJf+cG2fJEbCiT5v7b6ioGMLLPiFzt3cH b7EAqQqwqlCyFzAg== To: Johan Hovold , Marc Zyngier Cc: x86@kernel.org, platform-driver-x86@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold Subject: Re: [PATCH v3 19/19] irqdomain: Switch to per-domain locking In-Reply-To: <20221209140150.1453-20-johan+linaro@kernel.org> References: <20221209140150.1453-1-johan+linaro@kernel.org> <20221209140150.1453-20-johan+linaro@kernel.org> Date: Mon, 12 Dec 2022 15:14:34 +0100 Message-ID: <87mt7sbtf9.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 09 2022 at 15:01, Johan Hovold wrote: > The IRQ domain structures are currently protected by the global > irq_domain_mutex. Switch to using more fine-grained per-domain locking, > which may potentially speed up parallel probing somewhat. > > Note that the domain lock of the root domain (innermost domain) must be > used for hierarchical domains. For non-hierarchical domain (as for root > domains), the new root pointer is set to the domain itself so that > domain->root->mutex can be used in shared code paths. > > Also note that hierarchical domains should be constructed using > irq_domain_create_hierarchy() (or irq_domain_add_hierarchy()) to avoid > poking at irqdomain internals. While I agree in principle, this change really makes me nervous. Any fail in setting up domain->root correctly, e.g. by not using irq_domain_create_hierarchy(), cannot be detected and creates nasty to debug race conditions. So we need some debug mechanism which allows to validate that domain->root is set up correctly when domain->parent != NULL. Thanks, tglx