Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751558AbaJAT1I (ORCPT ); Wed, 1 Oct 2014 15:27:08 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:54440 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751185AbaJAT1G (ORCPT ); Wed, 1 Oct 2014 15:27:06 -0400 From: "Rafael J. Wysocki" To: Geert Uytterhoeven Cc: Len Brown , Pavel Machek , Simon Horman , Magnus Damm , Grygorii Strashko , Ulf Hansson , linux-pm@vger.kernel.org, linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] PM / clock_ops: Fix crash in clocks management code if !CONFIG_PM_RUNTIME Date: Wed, 01 Oct 2014 21:47:03 +0200 Message-ID: <23953734.KObJ4iLFUI@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.16.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1412188697-15317-1-git-send-email-geert+renesas@glider.be> References: <1412188697-15317-1-git-send-email-geert+renesas@glider.be> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday, October 01, 2014 08:38:17 PM Geert Uytterhoeven wrote: > Unlike the clocks management code for runtime PM, the code used for > system suspend does not check the pm_clock_entry.status field. > If pm_clk_acquire() failed, ce->status will be PCE_STATUS_ERROR, and > ce->clk will be a negative error code (e.g. 0xfffffffe = -2 = -ENOENT). > > Depending on the clock implementation, suspend or resume may crash with: > > Unable to handle kernel NULL pointer dereference at virtual address 00000026 > > (CCF clk_disable() has an IS_ERR_OR_NULL() check, while CCF clk_enable() > only has a NULL check; pre-CCF implementations may behave differently) > > While just checking for PCE_STATUS_ERROR would be sufficient, it doesn't > hurt to use the same state machine as is done for runtime PM, as this > makes the two versions more similar, and eligible for a future > consolidation. > > Signed-off-by: Geert Uytterhoeven > --- > This crash started to happen on armadillo-legacy during s2ram if > CONFIG_PM_RUNTIME is not set after applying "[PATCH v2 07/11] ARM: > shmobile: r8a7740/armadillo legacy: Add A4MP pm domain support" > (http://www.spinics.net/linux/lists/arm-kernel/msg365438.html), as > there's no NULL clock for the HDMI device. > > Most existing code calling pm_clk_suspend()/pm_clk_resume() is protected > by a check for CONFIG_PM_RUNTIME (davinci, keystone, omap1, > drivers/sh/pm_runtime.c), so it was not affected by this bug. > > Exceptions are: > - arch/arm/mach-shmobile/pm-r8a7779.c (marzen), > - arch/arm/mach-shmobile/pm-rmobile.c (r8a7740/armadillo and > sh7372/mackerel), > but it's difficult to assess from the code whether the bug is really > triggered on these platforms. > > Grygorii Strashko's "[PATCH v1 2/4] ARM: keystone: pm: switch to use > generic pm domains" is not affected, as pm_clk_add_clk() is only called > for existing clocks. > > If it crashes on marzen or mackerel, I think this fix needs to be > applied to stable, too. I don't have access to marzen or mackerel boards, > though. > > How to test: > - Build a kernel with CONFIG_PM_SLEEP/CONFIG_SUSPEND enabled, but > CONFIG_PM_RUNTIME disabled, > - echo 0 > /sys/module/printk/parameters/console_suspend, > - echo mem > /sys/power/state, > - wake up using e.g. gpio-keys or serial console activity. Do I think correctly that this would be 3.18 material? > --- > drivers/base/power/clock_ops.c | 19 +++++++++++++++---- > 1 file changed, 15 insertions(+), 4 deletions(-) > > diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c > index b99e6c06ee678ecb..78369305e0698109 100644 > --- a/drivers/base/power/clock_ops.c > +++ b/drivers/base/power/clock_ops.c > @@ -368,8 +368,13 @@ int pm_clk_suspend(struct device *dev) > > spin_lock_irqsave(&psd->lock, flags); > > - list_for_each_entry_reverse(ce, &psd->clock_list, node) > - clk_disable(ce->clk); > + list_for_each_entry_reverse(ce, &psd->clock_list, node) { > + if (ce->status < PCE_STATUS_ERROR) { > + if (ce->status == PCE_STATUS_ENABLED) > + clk_disable(ce->clk); > + ce->status = PCE_STATUS_ACQUIRED; > + } > + } > > spin_unlock_irqrestore(&psd->lock, flags); > > @@ -385,6 +390,7 @@ int pm_clk_resume(struct device *dev) > struct pm_subsys_data *psd = dev_to_psd(dev); > struct pm_clock_entry *ce; > unsigned long flags; > + int ret; > > dev_dbg(dev, "%s()\n", __func__); > > @@ -394,8 +400,13 @@ int pm_clk_resume(struct device *dev) > > spin_lock_irqsave(&psd->lock, flags); > > - list_for_each_entry(ce, &psd->clock_list, node) > - __pm_clk_enable(dev, ce->clk); > + list_for_each_entry(ce, &psd->clock_list, node) { > + if (ce->status < PCE_STATUS_ERROR) { > + ret = __pm_clk_enable(dev, ce->clk); > + if (!ret) > + ce->status = PCE_STATUS_ENABLED; > + } > + } > > spin_unlock_irqrestore(&psd->lock, flags); > > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/