Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753970AbaJASik (ORCPT ); Wed, 1 Oct 2014 14:38:40 -0400 Received: from andre.telenet-ops.be ([195.130.132.53]:56262 "EHLO andre.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752988AbaJASii (ORCPT ); Wed, 1 Oct 2014 14:38:38 -0400 From: Geert Uytterhoeven To: "Rafael J. Wysocki" , Len Brown , Pavel Machek , Simon Horman , Magnus Damm Cc: Grygorii Strashko , Ulf Hansson , linux-pm@vger.kernel.org, linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH] PM / clock_ops: Fix crash in clocks management code if !CONFIG_PM_RUNTIME Date: Wed, 1 Oct 2014 20:38:17 +0200 Message-Id: <1412188697-15317-1-git-send-email-geert+renesas@glider.be> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 -- 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/