Re: [PATCH] ACPI / hotplug: Fix concurrency issues and memory leaks

Yasuaki Ishimatsu
2013-02-13T03:08:02Z

Hi Rafael,

The patch seems good.
There is a comment below.

2013/02/13 9:19, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> This changeset is aimed at fixing a few different but related
> problems in the ACPI hotplug infrastructure.
>
> First of all, since notify handlers may be run in parallel with
> acpi_bus_scan(), acpi_bus_trim() and acpi_bus_hot_remove_device()
> and some of them are installed for ACPI handles that have no struct
> acpi_device objects attached (i.e. before those objects are created),
> those notify handlers have to take acpi_scan_lock to prevent races
> from taking place (e.g. a struct acpi_device is found to be present
> for the given ACPI handle, but right after that it is removed by
> acpi_bus_trim() running in parallel to the given notify handler).
> Moreover, since some of them call acpi_bus_scan() and
> acpi_bus_trim(), this leads to the conclusion that acpi_scan_lock
> should be acquired by the callers of these two funtions rather by
> these functions themselves.
>
> For these reasons, make all notify handlers that can handle device
> addition and eject events take acpi_scan_lock and remove the
> acpi_scan_lock locking from acpi_bus_scan() and acpi_bus_trim().
> Accordingly, update all of their users to make sure that they
> are always called under acpi_scan_lock.
>
> Furthermore, since eject operations are carried out asynchronously
> with respect to the notify events that trigger them, with the help
> of acpi_bus_hot_remove_device(), even if notify handlers take the
> ACPI scan lock, it still is possible that, for example,
> acpi_bus_trim() will run between acpi_bus_hot_remove_device() and
> the notify handler that scheduled its execution and that
> acpi_bus_trim() will remove the device node passed to
> acpi_bus_hot_remove_device() for ejection. In that case, the struct
> acpi_device object obtained by acpi_bus_hot_remove_device() will be
> invalid and not-so-funny things will ensue. To protect agaist that,
> make the users of acpi_bus_hot_remove_device() run get_device() on
> ACPI device node objects that are about to be passed to it and make
> acpi_bus_hot_remove_device() run put_device() on them and check if
> their ACPI handles are not NULL (make acpi_device_unregister() clear
> the device nodes' ACPI handles for that check to work).
>
> Finally, observe that acpi_os_hotplug_execute() actually can fail,
> in which case its caller ought to free memory allocated for the
> context object to prevent leaks from happening. It also needs to
> run put_device() on the device node that it ran get_device() on
> previously in that case. Modify the code accordingly.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> On top of linux-pm.git/linux-next.
>
> Thanks,
> Rafael
>
> ---
> drivers/acpi/acpi_memhotplug.c | 56 +++++++++++++++++++-----------
> drivers/acpi/container.c | 10 +++--
> drivers/acpi/dock.c | 19 ++++++++--
> drivers/acpi/processor_driver.c | 24 +++++++++---
> drivers/acpi/scan.c | 69 +++++++++++++++++++++++++------------
> drivers/pci/hotplug/acpiphp_glue.c | 6 +++
> drivers/pci/hotplug/sgi_hotplug.c | 5 ++
> include/acpi/acpi_bus.h | 3 +
> 8 files changed, 138 insertions(+), 54 deletions(-)
>
> Index: test/drivers/acpi/scan.c
> ===================================================================
> --- test.orig/drivers/acpi/scan.c
> +++ test/drivers/acpi/scan.c
> @@ -42,6 +42,18 @@ struct acpi_device_bus_id{
> struct list_head node;
> };
>
> +void acpi_scan_lock_acquire(void)
> +{
> + mutex_lock(&acpi_scan_lock);
> +}
> +EXPORT_SYMBOL_GPL(acpi_scan_lock_acquire);
> +
> +void acpi_scan_lock_release(void)
> +{
> + mutex_unlock(&acpi_scan_lock);
> +}
> +EXPORT_SYMBOL_GPL(acpi_scan_lock_release);
> +
> int acpi_scan_add_handler(struct acpi_scan_handler *handler)
> {
> if (!handler || !handler->attach)
> @@ -95,8 +107,6 @@ 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)
> @@ -107,7 +117,7 @@ static void __acpi_bus_trim(struct acpi_
> */
> void acpi_bus_hot_remove_device(void *context)
> {
> - struct acpi_eject_event *ej_event = (struct acpi_eject_event *) context;
> + struct acpi_eject_event *ej_event = context;
> struct acpi_device *device = ej_event->device;
> acpi_handle handle = device->handle;
> acpi_handle temp;
> @@ -118,11 +128,19 @@ void acpi_bus_hot_remove_device(void *co
>
> mutex_lock(&acpi_scan_lock);
>
> + /* If there is no handle, the device node has been unregistered. */
> + if (!device->handle) {
> + dev_dbg(&device->dev, "ACPI handle missing\n");
> + put_device(&device->dev);
> + goto out;
> + }
> +
> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> "Hot-removing device %s...\n", dev_name(&device->dev)));
>
> - __acpi_bus_trim(device);
> - /* Device node has been released. */
> + acpi_bus_trim(device);
> + /* Device node has been unregistered. */
> + put_device(&device->dev);
> device = NULL;
>
> if (ACPI_SUCCESS(acpi_get_handle(handle, "_LCK", &temp))) {
> @@ -151,6 +169,7 @@ void acpi_bus_hot_remove_device(void *co
> ost_code, NULL);
> }
>
> + out:
> mutex_unlock(&acpi_scan_lock);
> kfree(context);
> return;
> @@ -212,6 +231,7 @@ acpi_eject_store(struct device *d, struc
> goto err;
> }
>
> + get_device(&acpi_device->dev);
> ej_event->device = acpi_device;
> if (acpi_device->flags.eject_pending) {
> /* event originated from ACPI eject notification */
> @@ -224,7 +244,11 @@ acpi_eject_store(struct device *d, struc
> ej_event->event, ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
> }
>
> - acpi_os_hotplug_execute(acpi_bus_hot_remove_device, (void *)ej_event);
> + status = acpi_os_hotplug_execute(acpi_bus_hot_remove_device, ej_event);
> + if (ACPI_FAILURE(status)) {
> + put_device(&acpi_device->dev);
> + kfree(ej_event);
> + }
> err:
> return ret;
> }
> @@ -779,6 +803,7 @@ static void acpi_device_unregister(struc
> * no more references.
> */
> acpi_device_set_power(device, ACPI_STATE_D3_COLD);
> + device->handle = NULL;
> put_device(&device->dev);
> }
>
> @@ -1626,14 +1651,14 @@ static acpi_status acpi_bus_device_attac
> * there has been a real error. There just have been no suitable ACPI objects
> * in the table trunk from which the kernel could create a device and add an
> * appropriate driver.
> + *
> + * Must be called under acpi_scan_lock.
> */
> int acpi_bus_scan(acpi_handle handle)
> {
> void *device = NULL;
> int error = 0;
>
> - mutex_lock(&acpi_scan_lock);
> -
> if (ACPI_SUCCESS(acpi_bus_check_add(handle, 0, NULL, &device)))
> acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
> acpi_bus_check_add, NULL, NULL, &device);
> @@ -1644,7 +1669,6 @@ int acpi_bus_scan(acpi_handle handle)
> acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
> acpi_bus_device_attach, NULL, NULL, NULL);
>
> - mutex_unlock(&acpi_scan_lock);
> return error;
> }
> EXPORT_SYMBOL(acpi_bus_scan);
> @@ -1681,7 +1705,13 @@ static acpi_status acpi_bus_remove(acpi_
> return AE_OK;
> }
>
> -static void __acpi_bus_trim(struct acpi_device *start)
> +/**
> + * acpi_bus_trim - Remove ACPI device node and all of its descendants
> + * @start: Root of the ACPI device nodes subtree to remove.
> + *
> + * Must be called under acpi_scan_lock.
> + */
> +void acpi_bus_trim(struct acpi_device *start)
> {
> /*
> * Execute acpi_bus_device_detach() as a post-order callback to detach
> @@ -1698,13 +1728,6 @@ static void __acpi_bus_trim(struct acpi_
> 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);
>
> static int acpi_bus_scan_fixed(void)
> @@ -1762,23 +1785,27 @@ int __init acpi_scan_init(void)
> acpi_csrt_init();
> acpi_container_init();
>
> + mutex_lock(&acpi_scan_lock);
> /*
> * Enumerate devices in the ACPI namespace.
> */
> result = acpi_bus_scan(ACPI_ROOT_OBJECT);
> if (result)
> - return result;
> + goto out;
>
> result = acpi_bus_get_device(ACPI_ROOT_OBJECT, &acpi_root);
> if (result)
> - return result;
> + goto out;
>
> result = acpi_bus_scan_fixed();
> if (result) {
> acpi_device_unregister(acpi_root);
> - return result;
> + goto out;
> }
>
> acpi_update_all_gpes();
> - return 0;
> +
> + out:
> + mutex_unlock(&acpi_scan_lock);
> + return result;
> }
> Index: test/include/acpi/acpi_bus.h
> ===================================================================
> --- test.orig/include/acpi/acpi_bus.h
> +++ test/include/acpi/acpi_bus.h
> @@ -395,6 +395,9 @@ int acpi_bus_receive_event(struct acpi_b
> static inline int acpi_bus_generate_proc_event(struct acpi_device *device, u8 type, int data)
> { return 0; }
> #endif
> +
> +void acpi_scan_lock_acquire(void);
> +void acpi_scan_lock_release(void);
> int acpi_scan_add_handler(struct acpi_scan_handler *handler);
> int acpi_bus_register_driver(struct acpi_driver *driver);
> void acpi_bus_unregister_driver(struct acpi_driver *driver);
> Index: test/drivers/acpi/acpi_memhotplug.c
> ===================================================================
> --- test.orig/drivers/acpi/acpi_memhotplug.c
> +++ test/drivers/acpi/acpi_memhotplug.c
> @@ -153,14 +153,16 @@ acpi_memory_get_device_resources(struct
> return 0;
> }
>
> -static int
> -acpi_memory_get_device(acpi_handle handle,
> - struct acpi_memory_device **mem_device)
> +static int acpi_memory_get_device(acpi_handle handle,
> + struct acpi_memory_device **mem_device)
> {
> struct acpi_device *device = NULL;
> - int result;
> + int result = 0;
> +
> + acpi_scan_lock_acquire();
>
> - if (!acpi_bus_get_device(handle, &device) && device)
> + acpi_bus_get_device(handle, &device);
> + if (device)
> goto end;
>
> /*
> @@ -169,23 +171,28 @@ acpi_memory_get_device(acpi_handle handl
> */
> result = acpi_bus_scan(handle);
> if (result) {
> - acpi_handle_warn(handle, "Cannot add acpi bus\n");
> - return -EINVAL;
> + acpi_handle_warn(handle, "ACPI namespace scan failed\n");
> + result = -EINVAL;
> + goto out;
> }
> result = acpi_bus_get_device(handle, &device);
> if (result) {
> acpi_handle_warn(handle, "Missing device object\n");
> - return -EINVAL;
> + result = -EINVAL;
> + goto out;
> }
>
> - end:
> + end:
> *mem_device = acpi_driver_data(device);
> if (!(*mem_device)) {
> dev_err(&device->dev, "driver data not found\n");
> - return -ENODEV;
> + result = -ENODEV;
> + goto out;
> }
>
> - return 0;
> + out:
> + acpi_scan_lock_release();
> + return result;
> }
>
> static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
> @@ -305,6 +312,7 @@ static void acpi_memory_device_notify(ac
> struct acpi_device *device;
> struct acpi_eject_event *ej_event = NULL;
> u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
> + acpi_status status;
>
> switch (event) {
> case ACPI_NOTIFY_BUS_CHECK:
> @@ -327,29 +335,40 @@ static void acpi_memory_device_notify(ac
> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> "\nReceived EJECT REQUEST notification for device\n"));
>
> + status = AE_ERROR;
> + acpi_scan_lock_acquire();
> +
> if (acpi_bus_get_device(handle, &device)) {
> acpi_handle_err(handle, "Device doesn't exist\n");
> - break;
> + goto unlock;
> }
> mem_device = acpi_driver_data(device);
> if (!mem_device) {
> acpi_handle_err(handle, "Driver Data is NULL\n");
> - break;
> + goto unlock;
> }
>
> ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
> if (!ej_event) {
> pr_err(PREFIX "No memory, dropping EJECT\n");
> - break;
> + goto unlock;
> }
>
> + get_device(&device->dev);
> ej_event->device = device;
> ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
> - acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
> - (void *)ej_event);
> + /* The eject is carried out asynchronously. */
> + status = acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
> + ej_event);
> + if (ACPI_FAILURE(status)) {
> + put_device(&device->dev);
> + kfree(ej_event);
> + }
>
> - /* eject is performed asynchronously */
> - return;
> + unlock:
> + acpi_scan_lock_release();
> + if (ACPI_SUCCESS(status))
> + return;
> default:
> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> "Unsupported event [0x%x]\n", event));
> @@ -360,7 +379,6 @@ static void acpi_memory_device_notify(ac
>
> /* Inform firmware that the hotplug operation has completed */
> (void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
> - return;
> }
>
> static void acpi_memory_device_free(struct acpi_memory_device *mem_device)
> Index: test/drivers/acpi/processor_driver.c
> ===================================================================
> --- test.orig/drivers/acpi/processor_driver.c
> +++ test/drivers/acpi/processor_driver.c
> @@ -683,8 +683,11 @@ static void acpi_processor_hotplug_notif
> struct acpi_device *device = NULL;
> struct acpi_eject_event *ej_event = NULL;
> u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
> + acpi_status status;
> int result;
>
> + acpi_scan_lock_acquire();
> +
> switch (event) {
> case ACPI_NOTIFY_BUS_CHECK:
> case ACPI_NOTIFY_DEVICE_CHECK:
> @@ -733,25 +736,32 @@ static void acpi_processor_hotplug_notif
> break;
> }
>
> + get_device(&device->dev);
> ej_event->device = device;
> ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
> - acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
> - (void *)ej_event);
> -
> - /* eject is performed asynchronously */
> - return;
> + /* The eject is carried out asynchronously. */
> + status = acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
> + ej_event);
> + if (ACPI_FAILURE(status)) {
> + put_device(&device->dev);
> + kfree(ej_event);
> + break;
> + }
> + goto out;
>
> default:
> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> "Unsupported event [0x%x]\n", event));
>
> /* non-hotplug event; possibly handled by other handler */
> - return;
> + goto out;
> }
>
> /* Inform firmware that the hotplug operation has completed */
> (void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
> - return;
> +
> + out:

> + acpi_scan_lock_release();;

extra ";"

Thanks,
Yasuaki Ishimatsu

> }
>
> static acpi_status is_processor_device(acpi_handle handle)
> Index: test/drivers/acpi/container.c
> ===================================================================
> --- test.orig/drivers/acpi/container.c
> +++ test/drivers/acpi/container.c
> @@ -88,6 +88,8 @@ static void container_notify_cb(acpi_han
> acpi_status status;
> u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
>
> + acpi_scan_lock_acquire();
> +
> switch (type) {
> case ACPI_NOTIFY_BUS_CHECK:
> /* Fall through */
> @@ -130,18 +132,20 @@ static void container_notify_cb(acpi_han
> if (!acpi_bus_get_device(handle, &device) && device) {
> device->flags.eject_pending = 1;
> kobject_uevent(&device->dev.kobj, KOBJ_OFFLINE);
> - return;
> + goto out;
> }
> break;
>
> default:
> /* non-hotplug event; possibly handled by other handler */
> - return;
> + goto out;
> }
>
> /* Inform firmware that the hotplug operation has completed */
> (void) acpi_evaluate_hotplug_ost(handle, type, ost_code, NULL);
> - return;
> +
> + out:
> + acpi_scan_lock_release();
> }
>
> static bool is_container(acpi_handle handle)
> Index: test/drivers/acpi/dock.c
> ===================================================================
> --- test.orig/drivers/acpi/dock.c
> +++ test/drivers/acpi/dock.c
> @@ -744,7 +744,9 @@ static void acpi_dock_deferred_cb(void *
> {
> struct dock_data *data = context;
>
> + acpi_scan_lock_acquire();
> dock_notify(data->handle, data->event, data->ds);
> + acpi_scan_lock_release();
> kfree(data);
> }
>
> @@ -757,20 +759,31 @@ static int acpi_dock_notifier_call(struc
> if (event != ACPI_NOTIFY_BUS_CHECK && event != ACPI_NOTIFY_DEVICE_CHECK
> && event != ACPI_NOTIFY_EJECT_REQUEST)
> return 0;
> +
> + acpi_scan_lock_acquire();
> +
> list_for_each_entry(dock_station, &dock_stations, sibling) {
> if (dock_station->handle == handle) {
> struct dock_data *dd;
> + acpi_status status;
>
> dd = kmalloc(sizeof(*dd), GFP_KERNEL);
> if (!dd)
> - return 0;
> + break;
> +
> dd->handle = handle;
> dd->event = event;
> dd->ds = dock_station;
> - acpi_os_hotplug_execute(acpi_dock_deferred_cb, dd);
> - return 0 ;
> + status = acpi_os_hotplug_execute(acpi_dock_deferred_cb,
> + dd);
> + if (ACPI_FAILURE(status))
> + kfree(dd);
> +
> + break;
> }
> }
> +
> + acpi_scan_lock_release();
> return 0;
> }
>
> Index: test/drivers/pci/hotplug/acpiphp_glue.c
> ===================================================================
> --- test.orig/drivers/pci/hotplug/acpiphp_glue.c
> +++ test/drivers/pci/hotplug/acpiphp_glue.c
> @@ -1218,6 +1218,8 @@ static void _handle_hotplug_event_bridge
> handle = hp_work->handle;
> type = hp_work->type;
>
> + acpi_scan_lock_acquire();
> +
> if (acpi_bus_get_device(handle, &device)) {
> /* This bridge must have just been physically inserted */
> handle_bridge_insertion(handle, type);
> @@ -1295,6 +1297,7 @@ static void _handle_hotplug_event_bridge
> }
>
> out:
> + acpi_scan_lock_release();
> kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
> }
>
> @@ -1341,6 +1344,8 @@ static void _handle_hotplug_event_func(s
>
> func = (struct acpiphp_func *)context;
>
> + acpi_scan_lock_acquire();
> +
> switch (type) {
> case ACPI_NOTIFY_BUS_CHECK:
> /* bus re-enumerate */
> @@ -1371,6 +1376,7 @@ static void _handle_hotplug_event_func(s
> break;
> }
>
> + acpi_scan_lock_release();
> kfree(hp_work); /* allocated in handle_hotplug_event_func */
> }
>
> Index: test/drivers/pci/hotplug/sgi_hotplug.c
> ===================================================================
> --- test.orig/drivers/pci/hotplug/sgi_hotplug.c
> +++ test/drivers/pci/hotplug/sgi_hotplug.c
> @@ -425,6 +425,7 @@ static int enable_slot(struct hotplug_sl
> pdevice = NULL;
> }
>
> + acpi_scan_lock_acquire();
> /*
> * Walk the rootbus node's immediate children looking for
> * the slot's device node(s). There can be more than
> @@ -458,6 +459,7 @@ static int enable_slot(struct hotplug_sl
> }
> }
> }
> + acpi_scan_lock_release();
> }
>
> /* Call the driver for the new device */
> @@ -508,6 +510,7 @@ static int disable_slot(struct hotplug_s
> /* Get the rootbus node pointer */
> phandle = PCI_CONTROLLER(slot->pci_bus)->acpi_handle;
>
> + acpi_scan_lock_acquire();
> /*
> * Walk the rootbus node's immediate children looking for
> * the slot's device node(s). There can be more than
> @@ -538,7 +541,7 @@ static int disable_slot(struct hotplug_s
> acpi_bus_trim(device);
> }
> }
> -
> + acpi_scan_lock_release();
> }
>
> /* Free the SN resources assigned to the Linux device.*/
>