Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751909AbaKCKxP (ORCPT ); Mon, 3 Nov 2014 05:53:15 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:35983 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751114AbaKCKxN (ORCPT ); Mon, 3 Nov 2014 05:53:13 -0500 Date: Mon, 3 Nov 2014 10:53:08 +0000 From: Luis Henriques To: Geert Uytterhoeven Cc: stable , "Rafael J. Wysocki" , Len Brown , Pavel Machek , Simon Horman , Magnus Damm , Grygorii Strashko , Ulf Hansson , Linux PM list , Linux-sh list , "linux-kernel@vger.kernel.org" , Geert Uytterhoeven Subject: Re: [PATCH] PM / clock_ops: Fix crash in clocks management code if !CONFIG_PM_RUNTIME Message-ID: <20141103105308.GF6874@hercules> References: <1412188697-15317-1-git-send-email-geert+renesas@glider.be> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 30, 2014 at 10:06:25AM +0100, Geert Uytterhoeven wrote: > Upstream commit a968bed78b549b4c61d4a46e59161fc1f60f96a6 > Author: Geert Uytterhoeven > Date: Wed Oct 1 20:38:17 2014 +0200 > > PM / clk: Fix crash in clocks management code if !CONFIG_PM_RUNTIME > > > Simon tried it on mackerel. It did not crash, but caused a warning and > backtrace: > > WARNING: CPU: 0 PID: 1420 at drivers/sh/clk/core.c:240 > __clk_disable+0x80/0x90() > Trying to disable clock c04bd4d8 with 0 usecount > > which got fixed by the patch. So I think it should be applied to > -stable (v3.14 and up). > Thanks, I'm queuing it for the 3.16. Cheers, -- Lu?s > Thanks! > > On Wed, Oct 1, 2014 at 8:38 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. > > --- > > 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); > > > > -- > > 1.9.1 > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds > -- > To unsubscribe from this list: send the line "unsubscribe stable" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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/