From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: [PATCH 1/2] ACPI / scan: Make acpi_bus_hot_remove_device() acquire the scan lock Date: Sat, 09 Feb 2013 15:29:25 +0100 Message-ID: <3006340.mglZY9ZPKY@vostro.rjw.lan> References: <1873429.MS5RQDxTye@vostro.rjw.lan> <1468930.acVuhKfKYv@vostro.rjw.lan> <2074190.mMzUc3TOxk@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <2074190.mMzUc3TOxk@vostro.rjw.lan> Sender: linux-kernel-owner@vger.kernel.org To: ACPI Devel Maling List Cc: Bjorn Helgaas , Mika Westerberg , Yinghai Lu , Jiang Liu , Toshi Kani , LKML , Yasuaki Ishimatsu List-Id: linux-acpi@vger.kernel.org From: Rafael J. Wysocki The ACPI scan lock has been introduced to prevent acpi_bus_scan() and acpi_bus_trim() from running in parallel with each other for overlapping ACPI namespace scopes. However, it is not sufficient to do that, because if acpi_bus_scan() is run (for an overlapping namespace scope) right after the acpi_bus_trim() in acpi_bus_hot_remove_device(), the subsequent eject will remove devices without removing the corresponding struct acpi_device objects (and possibly companion "physical" device objects). Therefore acpi_bus_hot_remove_device() has to acquire the scan lock before carrying out the bus trimming and hold it through the evaluation of _EJ0, so make that happen. Signed-off-by: Rafael J. Wysocki --- drivers/acpi/scan.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) Index: test/drivers/acpi/scan.c =================================================================== --- test.orig/drivers/acpi/scan.c +++ test/drivers/acpi/scan.c @@ -95,6 +95,8 @@ acpi_device_modalias_show(struct device } static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL); +static void __acpi_bus_trim(struct acpi_device *start); + /** * acpi_bus_hot_remove_device: hot-remove a device and its children * @context: struct acpi_eject_event pointer (freed in this func) @@ -114,10 +116,12 @@ void acpi_bus_hot_remove_device(void *co acpi_status status = AE_OK; u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */ + mutex_lock(&acpi_scan_lock); + ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Hot-removing device %s...\n", dev_name(&device->dev))); - acpi_bus_trim(device); + __acpi_bus_trim(device); /* Device node has been released. */ device = NULL; @@ -146,18 +150,14 @@ void acpi_bus_hot_remove_device(void *co status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL); if (ACPI_FAILURE(status)) { if (status != AE_NOT_FOUND) - printk(KERN_WARNING PREFIX - "Eject device failed\n"); - goto err_out; - } + acpi_handle_warn(handle, "Eject failed\n"); - kfree(context); - return; + /* Tell the firmware the hot-remove operation has failed. */ + acpi_evaluate_hotplug_ost(handle, ej_event->event, + ost_code, NULL); + } -err_out: - /* Inform firmware the hot-remove operation has completed w/ error */ - (void) acpi_evaluate_hotplug_ost(handle, - ej_event->event, ost_code, NULL); + mutex_unlock(&acpi_scan_lock); kfree(context); return; } @@ -1686,10 +1686,8 @@ static acpi_status acpi_bus_remove(acpi_ return AE_OK; } -void acpi_bus_trim(struct acpi_device *start) +static void __acpi_bus_trim(struct acpi_device *start) { - mutex_lock(&acpi_scan_lock); - /* * Execute acpi_bus_device_detach() as a post-order callback to detach * all ACPI drivers from the device nodes being removed. @@ -1704,7 +1702,12 @@ void acpi_bus_trim(struct acpi_device *s acpi_walk_namespace(ACPI_TYPE_ANY, start->handle, ACPI_UINT32_MAX, NULL, acpi_bus_remove, NULL, NULL); acpi_bus_remove(start->handle, 0, NULL, NULL); +} +void acpi_bus_trim(struct acpi_device *start) +{ + mutex_lock(&acpi_scan_lock); + __acpi_bus_trim(start); mutex_unlock(&acpi_scan_lock); } EXPORT_SYMBOL_GPL(acpi_bus_trim);