From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753264AbbDGJFr (ORCPT ); Tue, 7 Apr 2015 05:05:47 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:27049 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752835AbbDGJFm (ORCPT ); Tue, 7 Apr 2015 05:05:42 -0400 From: Xie XiuQi To: , CC: , , , Subject: [PATCH] ACPI / HOTPLUG: fix device->physical_node_lock deadlock Date: Tue, 7 Apr 2015 17:03:12 +0800 Message-ID: <1428397392-26200-1-git-send-email-xiexiuqi@huawei.com> X-Mailer: git-send-email 1.7.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.100.166] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I meet a deadlock during cpu hotplug. The code path is bellow: Call Trace: [] dump_stack+0x19/0x1b [] validate_chain.isra.43+0xf4a/0x1120 [] ? sched_clock+0x9/0x10 [] ? sched_clock_local+0x1d/0x80 [] ? sched_clock_cpu+0xa8/0x100 [] __lock_acquire+0x3c6/0xb70 [] ? sched_clock_cpu+0xa8/0x100 [] lock_acquire+0xa2/0x1f0 [] ? acpi_scan_is_offline+0x2c/0xa3 [] mutex_lock_nested+0x94/0x3f0 [] ? acpi_scan_is_offline+0x2c/0xa3 [] ? acpi_scan_is_offline+0x2c/0xa3 [] ? trace_hardirqs_on+0xd/0x10 [] acpi_scan_is_offline+0x2c/0xa3 --> LOCK (DEADLOCK) [] acpi_container_offline+0x32/0x4e [] container_offline+0x19/0x20 [] device_offline+0x95/0xc0 [] acpi_bus_offline+0xbc/0x126 --> LOCK [] acpi_device_hotplug+0x236/0x46b [] acpi_hotplug_work_fn+0x1e/0x29 [] process_one_work+0x220/0x710 [] ? process_one_work+0x1b4/0x710 [] worker_thread+0x11b/0x3a0 [] ? process_one_work+0x710/0x710 [] kthread+0xed/0x100 [] ? insert_kthread_work+0x80/0x80 [] ret_from_fork+0x7c/0xb0 [] ? insert_kthread_work+0x80/0x80 This deadlock was introduced by commit caa73ea ("ACPI / hotplug / driver core: Handle containers in a special way"). In this patch, we just introduced a lockless version __acpi_scan_is_offline() for acpi_container_offline(), to avoid this deadlock. Cc: # v3.14+ Signed-off-by: Xie XiuQi --- drivers/acpi/container.c | 2 +- drivers/acpi/internal.h | 1 + drivers/acpi/scan.c | 15 ++++++++++++--- 3 files changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/acpi/container.c b/drivers/acpi/container.c index c8ead9f..43bda3b2 100644 --- a/drivers/acpi/container.c +++ b/drivers/acpi/container.c @@ -50,7 +50,7 @@ static int acpi_container_offline(struct container_dev *cdev) /* Check all of the dependent devices' physical companions. */ list_for_each_entry(child, &adev->children, node) - if (!acpi_scan_is_offline(child, false)) + if (!__acpi_scan_is_offline(child, false)) return -EBUSY; return 0; diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h index 56b321a..3b7a07b 100644 --- a/drivers/acpi/internal.h +++ b/drivers/acpi/internal.h @@ -80,6 +80,7 @@ void acpi_apd_init(void); acpi_status acpi_hotplug_schedule(struct acpi_device *adev, u32 src); bool acpi_queue_hotplug_work(struct work_struct *work); void acpi_device_hotplug(struct acpi_device *adev, u32 src); +bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent); bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent); /* -------------------------------------------------------------------------- diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index bbca783..ea55a9a 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -293,13 +293,12 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha } static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL); -bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent) +/* Must be called under physical_node_lock. */ +bool __acpi_scan_is_offline(struct acpi_device *adev, bool uevent) { struct acpi_device_physical_node *pn; bool offline = true; - mutex_lock(&adev->physical_node_lock); - list_for_each_entry(pn, &adev->physical_node_list, node) if (device_supports_offline(pn->dev) && !pn->dev->offline) { if (uevent) @@ -309,7 +308,17 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent) break; } + return offline; +} + +bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent) +{ + bool offline = true; + + mutex_lock(&adev->physical_node_lock); + offline = __acpi_scan_is_offline(adev, uevent); mutex_unlock(&adev->physical_node_lock); + return offline; } -- 1.8.3.1