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 A9118C43217 for ; Thu, 13 Oct 2022 21:34:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229507AbiJMVeq (ORCPT ); Thu, 13 Oct 2022 17:34:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229700AbiJMVeo (ORCPT ); Thu, 13 Oct 2022 17:34:44 -0400 Received: from relay2-d.mail.gandi.net (relay2-d.mail.gandi.net [217.70.183.194]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F137F31; Thu, 13 Oct 2022 14:34:38 -0700 (PDT) Received: (Authenticated sender: alexandre.belloni@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 4B0D740003; Thu, 13 Oct 2022 21:34:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1665696877; 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=S/j4VwaT4LG3Yaw516KnXpuXfG1/DCE/NaX0TVRcb+0=; b=MyTRzYh8SaclkkMeCwVfm//yVoYxD6Nv2RNcJl3SDMzwWeu2D7dRus81kMKwU36AxnC3F7 A+WquWGTJw76AwW8kQAZevFMBz1v9xmlzDkqtBKVvXrcrH8yS9MmsPixCy2djZ/17v7kTZ xNDvfTOvWXoNgOUQGOnJWyLZCof7eNAov8e7MjClBnNCXnEjiimVx/c/+jzsNBBRqz5lXj PET7fEtZoPfmPKIknd0gki1lcOT/cd265emz8CpYUN5S+EQhfoAizgI3V6cAlbT2dnddAS ZdqtgOujsskfhrMyJRkL1xW7mbSPeHBzVfAV7zEnaURqdVFoRa3f+RlTqS/6VQ== Date: Thu, 13 Oct 2022 23:34:35 +0200 From: Alexandre Belloni To: "Rafael J. Wysocki" Cc: Bjorn Helgaas , "Rafael J. Wysocki" , Alessandro Zummo , Mario Limonciello , linux-rtc@vger.kernel.org, LKML , Linux ACPI , Linux PM , Mel Gorman Subject: Re: [PATCH] rtc: rtc-cmos: Fix event handler registration ordering issue Message-ID: References: <5629262.DvuYhMxLoT@kreacher> <20221012205757.GA3118709@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 13/10/2022 13:38:31+0200, Rafael J. Wysocki wrote: > On Wed, Oct 12, 2022 at 11:00 PM Bjorn Helgaas wrote: > > > > On Wed, Oct 12, 2022 at 08:07:01PM +0200, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki > > > > > > Because acpi_install_fixed_event_handler() enables the event > > > automatically on success, it is incorrect to call it before the > > > handler routine passed to it is ready to handle events. > > > > > > Unfortunately, the rtc-cmos driver does exactly the incorrect thing > > > by calling cmos_wake_setup(), which passes rtc_handler() to > > > acpi_install_fixed_event_handler(), before cmos_do_probe(), because > > > rtc_handler() uses dev_get_drvdata() to get to the cmos object > > > pointer and the driver data pointer is only populated in > > > cmos_do_probe(). > > > > > > This leads to a NULL pointer dereference in rtc_handler() on boot > > > if the RTC fixed event happens to be active at the init time. > > > > > > To address this issue, change the initialization ordering of the > > > driver so that cmos_wake_setup() is always called after a successful > > > cmos_do_probe() call. > > > > > > While at it, change cmos_pnp_probe() to call cmos_do_probe() after > > > the initial if () statement used for computing the IRQ argument to > > > be passed to cmos_do_probe() which is cleaner than calling it in > > > each branch of that if () (local variable "irq" can be of type int, > > > because it is passed to that function as an argument of type int). > > > > > > Note that commit 6492fed7d8c9 ("rtc: rtc-cmos: Do not check > > > ACPI_FADT_LOW_POWER_S0") caused this issue to affect a larger number > > > of systems, because previously it only affected systems with > > > ACPI_FADT_LOW_POWER_S0 set, but it is present regardless of that > > > commit. > > > > > > Fixes: 6492fed7d8c9 ("rtc: rtc-cmos: Do not check ACPI_FADT_LOW_POWER_S0") > > > Fixes: a474aaedac99 ("rtc-cmos: move wake setup from ACPI glue into RTC driver") > > > Link: https://lore.kernel.org/linux-acpi/20221010141630.zfzi7mk7zvnmclzy@techsingularity.net/ > > > Reported-by: Mel Gorman > > > Signed-off-by: Rafael J. Wysocki > > > > Reviewed-by: Bjorn Helgaas > > > > Yep, I blew it with a474aaedac99, sorry about that. > > > > Possibly could call cmos_wake_setup() from cmos_do_probe() instead of > > from cmos_pnp_probe() and cmos_platform_probe()? > > Sounds good. > > I would prefer to send a separate patch for this on top of the > $subject one, unless Alexandre wants me to do it all in one go. > > Alexandre, what's your preference here? Or would you prefer if I > pushed this forward? > I applied your patch, feel free to improve on top of that ;) > > Then there would be a single call site and it would be closer to the actual dependency on > > dev_set_drvdata(). Either way is fine with me. > > OK > > > Unrelated, but I happened to notice that pnp_irq() returns -1 for > > failure, and this note suggests that possibly returning 0 would be > > better: > > > > https://lore.kernel.org/r/CAHk-=wg2Pkb9kbfbstbB91AJA2SF6cySbsgHG-iQMq56j3VTcA@mail.gmail.com > > Probably. > > In that case, though, it would be prudent to also explicitly discard > IRQ resources where start is equal to 0. > > > > > > --- > > > drivers/rtc/rtc-cmos.c | 29 +++++++++++++++++++---------- > > > 1 file changed, 19 insertions(+), 10 deletions(-) > > > > > > Index: linux-pm/drivers/rtc/rtc-cmos.c > > > =================================================================== > > > --- linux-pm.orig/drivers/rtc/rtc-cmos.c > > > +++ linux-pm/drivers/rtc/rtc-cmos.c > > > @@ -1352,10 +1352,10 @@ static void cmos_check_acpi_rtc_status(s > > > > > > static int cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) > > > { > > > - cmos_wake_setup(&pnp->dev); > > > + int irq, ret; > > > > > > if (pnp_port_start(pnp, 0) == 0x70 && !pnp_irq_valid(pnp, 0)) { > > > - unsigned int irq = 0; > > > + irq = 0; > > > #ifdef CONFIG_X86 > > > /* Some machines contain a PNP entry for the RTC, but > > > * don't define the IRQ. It should always be safe to > > > @@ -1364,13 +1364,17 @@ static int cmos_pnp_probe(struct pnp_dev > > > if (nr_legacy_irqs()) > > > irq = RTC_IRQ; > > > #endif > > > - return cmos_do_probe(&pnp->dev, > > > - pnp_get_resource(pnp, IORESOURCE_IO, 0), irq); > > > } else { > > > - return cmos_do_probe(&pnp->dev, > > > - pnp_get_resource(pnp, IORESOURCE_IO, 0), > > > - pnp_irq(pnp, 0)); > > > + irq = pnp_irq(pnp, 0); > > > } > > > + > > > + ret = cmos_do_probe(&pnp->dev, pnp_get_resource(pnp, IORESOURCE_IO, 0), irq); > > > + if (ret) > > > + return ret; > > > + > > > + cmos_wake_setup(&pnp->dev); > > > + > > > + return 0; > > > } > > > > > > static void cmos_pnp_remove(struct pnp_dev *pnp) > > > @@ -1454,10 +1458,9 @@ static inline void cmos_of_init(struct p > > > static int __init cmos_platform_probe(struct platform_device *pdev) > > > { > > > struct resource *resource; > > > - int irq; > > > + int irq, ret; > > > > > > cmos_of_init(pdev); > > > - cmos_wake_setup(&pdev->dev); > > > > > > if (RTC_IOMAPPED) > > > resource = platform_get_resource(pdev, IORESOURCE_IO, 0); > > > @@ -1467,7 +1470,13 @@ static int __init cmos_platform_probe(st > > > if (irq < 0) > > > irq = -1; > > > > > > - return cmos_do_probe(&pdev->dev, resource, irq); > > > + ret = cmos_do_probe(&pdev->dev, resource, irq); > > > + if (ret) > > > + return ret; > > > + > > > + cmos_wake_setup(&pdev->dev); > > > + > > > + return 0; > > > } > > > > > > static int cmos_platform_remove(struct platform_device *pdev) > > > > > > > > > -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com