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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 CF87AC433E7 for ; Fri, 16 Oct 2020 13:42:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 759E720848 for ; Fri, 16 Oct 2020 13:42:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="LJz8u0pL"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="p6ALofZG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2408350AbgJPNmc (ORCPT ); Fri, 16 Oct 2020 09:42:32 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:44696 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407058AbgJPNm3 (ORCPT ); Fri, 16 Oct 2020 09:42:29 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1602855747; 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=3qZ3wBDxLlc4y2LdirJcgerLsIDb2RZnNo4XttMjq30=; b=LJz8u0pLozePlNZYgZvvpyj/qhL5C+MTWzbqD1eu+aQX3xvB+nIhmh51tGKAbVFdSMSXXn bgOI8oFYUBzoQV2R+l6uLsM9+2lhxK6DweO9H6eQGNE7z5ectfb0823f66a9pezbNcg2zO enw/POzOO9vGilP73TJDT0qmYRyID39Q0DeUpXBnADcGpy+rnJg6Yoye+HPQbOb/NaLP/Q cHlwZKPmNQVKIZfJlA/5XDTOC9Y6Fz86kLHgzEhFatJ70/ZzqEeSjO6FOBmow5gvGXsXbB 9G7vek0DpCNRR1WoZ3IQk67AHjNsdE8YTrr/1rKFVFQh7COU+hNuvn5Ug2trCg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1602855747; 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=3qZ3wBDxLlc4y2LdirJcgerLsIDb2RZnNo4XttMjq30=; b=p6ALofZGtMZBBzMf1J4rWNqTtXAgvjanZlwcjpEBhrQUzIw/w2upgOl64RezJ32xRpQ8Tn 9sxasXqA3HsrFyAQ== To: Marc Zyngier , Greentime Hu Cc: jason@lakedaemon.net, palmer@dabbelt.com, paul.walmsley@sifive.com, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH 2/2] irqchip/sifive-plic: Fix the interrupt was enabled accidentally issue. In-Reply-To: <5bedfbc723665c979eb73eefadb21970@kernel.org> References: <20201012135724.110579-1-greentime.hu@sifive.com> <20201012135724.110579-2-greentime.hu@sifive.com> <5bedfbc723665c979eb73eefadb21970@kernel.org> Date: Fri, 16 Oct 2020 15:42:27 +0200 Message-ID: <87ft6ethh8.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 15 2020 at 22:23, Marc Zyngier wrote: > On 2020-10-12 14:57, Greentime Hu wrote: >> In commit 2ca0b460bbcb ("genirq/affinity: Make affinity setting if >> activated opt-in"), This commit sha does not exist in mainline. Referencing a random stable kernel tree is useless. >> it added irqd_affinity_on_activate() checking in the function >> irq_set_affinity_deactivated() so it will return false here. >> In that case, it will call irq_try_set_affinity() -> plic_irq_toggle() >> which will enable the interrupt to cause the CPU hang. >> @@ -183,10 +183,14 @@ static int plic_irqdomain_map(struct irq_domain >> *d, unsigned int irq, >> irq_hw_number_t hwirq) >> { >> struct plic_priv *priv = d->host_data; >> + struct irq_data *irqd; >> >> irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data, >> handle_fasteoi_irq, NULL, NULL); >> irq_set_noprobe(irq); >> + irqd = irq_get_irq_data(irq); >> + irqd_set_single_target(irqd); >> + irqd_set_affinity_on_activate(irqd); >> irq_set_affinity(irq, &priv->lmask); >> return 0; >> } > > How does this fix anything? The plic driver doesn't have an activate > callback, so how does it make any difference? I get the feeling this > papers over another issue. The existence of the activate callback is not really the interesting part. And of course the analysis is completely bogus. The referenced commit is a follow up to: baedb87d1b53 ("genirq/affinity: Handle affinity setting on inactive interrupts correctly") which was added on Jul 17 and the fix was added on Jul 24: f0c7baca1800 ("genirq/affinity: Make affinity setting if activated opt-in") The latter restored the original behaviour within 7 days, except for x86. And the original behaviour was that the core did not care about the activated state at all. It just invoked irqchip->irq_set_affinity() unconditionally, which is still does except when the interrupt is marked with irqd_set_affinity_on_activate(). So the plic code had this problem before that change already: irq_set_noprobe(irq); irq_set_affinity(irq, &priv->lmask); Mapping happens way before anything else, so Hu is definitely barking up the wrong tree. What the patch works around is the irq_set_affinity() callback which is completely bogus and still broken even after that duct tape which" fixes" the boot fail. irq_set_affinity() can be called on masked interrupts so this: plic_irq_toggle(&priv->lmask, d, 0); plic_irq_toggle(cpumask_of(cpu), d, 1); will always unconditionally unmask the interrupt when affinity is changed. plic_irq_toggle(cpumask_of(cpu), d, !irqd_irq_masked(d)); is all it needs to work everywhere. Obvious, right? The changelog wants to be "...: Fix broken irq_set_affinity() callback" and the Fixes: tag referencing the commit which introduced that unconditional unmask. Oh well. Thanks, tglx