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=-8.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 E7DC2C433DB for ; Mon, 22 Feb 2021 11:27:04 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 7771B64DEC for ; Mon, 22 Feb 2021 11:27:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7771B64DEC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.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=4PTEMiFF12NI4h0wcyO0ssKL8Pgz0DDMZxRF4SDKpZ0=; b=SGp6PfcXKAsi/SCAgpWCwJLCm mxsHDCClBZNcT+Ll57TRGpiNvStKxQ4Qj0WLTB4/Um5LCK5NnGpIIW8/66RX3WWsp+FTQH02b8V1Y 4E+xiaA8Cg4oO+arptvsK9hftRmroj7ToZtyTUfPak0zwo3Rmj67EllhGAREzlb3hykMFyNgEkpD6 9ebA8cwo1hcKfZ5LhAkOSPG10fPz2QY6q+J6vAEw8RM03nkksdP6tWKjSOvljlEA6DBFpYrH8HYgC joHi9g2Gqm7gfQIIPyQPOxp/iHTDqDywQFqXaQ1hbhYTR7NgGhu7BOly4LJao6k0cP9nNCVa16tVa iAeCekwbQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lE9Lf-0005Ab-Jc; Mon, 22 Feb 2021 11:25:55 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lE9Lc-00059Y-9H for linux-arm-kernel@lists.infradead.org; Mon, 22 Feb 2021 11:25:53 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 614EB1FB; Mon, 22 Feb 2021 03:25:49 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.51.127]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B01183F73B; Mon, 22 Feb 2021 03:25:47 -0800 (PST) Date: Mon, 22 Feb 2021 11:25:44 +0000 From: Mark Rutland To: Marc Zyngier Subject: Re: [PATCH 5/8] arm64: irq: add a default handle_irq panic function Message-ID: <20210222112544.GB70951@C02TD0UTHF1T.local> References: <20210219113904.41736-1-mark.rutland@arm.com> <20210219113904.41736-6-mark.rutland@arm.com> <20210222095913.GA70951@C02TD0UTHF1T.local> <1d2c27d72b9b2cbdb83d25165a20559a@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1d2c27d72b9b2cbdb83d25165a20559a@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210222_062552_434921_83FF68CC X-CRM114-Status: GOOD ( 16.05 ) 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: catalin.marinas@arm.com, marcan@marcan.st, linux-kernel@vger.kernel.org, james.morse@arm.com, tglx@linutronix.de, will@kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Feb 22, 2021 at 10:48:11AM +0000, Marc Zyngier wrote: > On 2021-02-22 09:59, Mark Rutland wrote: > > On Fri, Feb 19, 2021 at 11:39:01AM +0000, Mark Rutland wrote: > > > +void (*handle_arch_irq)(struct pt_regs *) __ro_after_init = > > > default_handle_irq; > > > > > > int __init set_handle_irq(void (*handle_irq)(struct pt_regs *)) > > > { > > > - if (handle_arch_irq) > > > + if (handle_arch_irq != default_handle_irq) > > > return -EBUSY; > > > > > > handle_arch_irq = handle_irq; > > > @@ -87,7 +92,7 @@ void __init init_IRQ(void) > > > init_irq_stacks(); > > > init_irq_scs(); > > > irqchip_init(); > > > - if (!handle_arch_irq) > > > + if (handle_arch_irq == default_handle_irq) > > > panic("No interrupt controller found."); > > It also seems odd to have both default_handle_irq() that panics, > and init_IRQ that panics as well. Not a big deal, but maybe > we should just drop this altogether and get the firework on the > first interrupt. My gut feeling was that both were useful, and served slightly different cases: * The panic in default_handle_irq() helps if we unexpectedly unmask IRQ too early. This is mostly a nicety over the current behaviour of branching to NULL in this case. * The panic in init_IRQ() gives us a consistent point at which we can note the absence of a root IRQ controller even if all IRQs are quiescent. This is a bit nicer to debug than seeing a load of driver probes fail their request_irq() or whatever. ... so I'd err on the side of keeping both, but if you think otherwise I'm happy to change this. Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel