Re: [PATCH 2/7] ACPI / scan: Introduce common code for ACPI-based device hotplug

[Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>]

2013/02/19 15:43, Yasuaki Ishimatsu wrote:
> Hi Rafael,
>
> I have comments. Please see below.
>
> 2013/02/18 0:21, Rafael J. Wysocki wrote:
>> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>>
>> Multiple drivers handling hotplug-capable ACPI device nodes install
>> notify handlers covering the same types of events in a very similar
>> way.  Moreover, those handlers are installed in separate namespace
>> walks, although that really should be done during namespace scans
>> carried out by acpi_bus_scan().  This leads to substantial code
>> duplication, unnecessary overhead and behavior that is hard to
>> follow.
>>
>> For this reason, introduce common code in drivers/acpi/scan.c for
>> handling hotplug-related notification and carrying out device
>> insertion and eject operations in a generic fashion, such that it
>> may be used by all of the relevant drivers in the future.  To cover
>> the existing differences between those drivers introduce struct
>> acpi_hotplug_profile for representing collections of hotplug
>> settings associated with different ACPI scan handlers that can be
>> used by the drivers to make the common code reflect their current
>> behavior.
>>
>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> ---
>>   drivers/acpi/scan.c     |  271 +++++++++++++++++++++++++++++++++++++-----------
>>   include/acpi/acpi_bus.h |    7 +
>>   2 files changed, 220 insertions(+), 58 deletions(-)
>>
>> Index: test/include/acpi/acpi_bus.h
>> ===================================================================
>> --- test.orig/include/acpi/acpi_bus.h
>> +++ test/include/acpi/acpi_bus.h
>> @@ -88,11 +88,18 @@ struct acpi_device;
>>    * -----------------
>>    */
>>
>> +struct acpi_hotplug_profile {
>> +    bool enabled:1;
>> +    bool uevents:1;
>> +    bool autoeject:1;
>> +};
>> +
>>   struct acpi_scan_handler {
>>       const struct acpi_device_id *ids;
>>       struct list_head list_node;
>>       int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id);
>>       void (*detach)(struct acpi_device *dev);
>> +    struct acpi_hotplug_profile hotplug;
>>   };
>>
>>   /*
>> Index: test/drivers/acpi/scan.c
>> ===================================================================
>> --- test.orig/drivers/acpi/scan.c
>> +++ test/drivers/acpi/scan.c
>> @@ -107,32 +107,19 @@ acpi_device_modalias_show(struct device
>>   }
>>   static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
>>
>> -/**
>> - * acpi_bus_hot_remove_device: hot-remove a device and its children
>> - * @context: struct acpi_eject_event pointer (freed in this func)
>> - *
>> - * Hot-remove a device and its children. This function frees up the
>> - * memory space passed by arg context, so that the caller may call
>> - * this function asynchronously through acpi_os_hotplug_execute().
>> - */
>> -void acpi_bus_hot_remove_device(void *context)
>> +static int acpi_scan_hot_remove(struct acpi_device *device)
>>   {
>> -    struct acpi_eject_event *ej_event = context;
>> -    struct acpi_device *device = ej_event->device;
>>       acpi_handle handle = device->handle;
>> -    acpi_handle temp;
>> +    acpi_handle not_used;
>>       struct acpi_object_list arg_list;
>>       union acpi_object arg;
>> -    acpi_status status = AE_OK;
>> -    u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
>> -
>> -    mutex_lock(&acpi_scan_lock);
>> +    acpi_status status;
>>
>>       /* If there is no handle, the device node has been unregistered. */
>> -    if (!device->handle) {
>> +    if (!handle) {
>>           dev_dbg(&device->dev, "ACPI handle missing\n");
>>           put_device(&device->dev);
>> -        goto out;
>> +        return -EINVAL;
>>       }
>>
>>       ACPI_DEBUG_PRINT((ACPI_DB_INFO,
>> @@ -143,7 +130,7 @@ void acpi_bus_hot_remove_device(void *co
>>       put_device(&device->dev);
>>       device = NULL;
>>
>> -    if (ACPI_SUCCESS(acpi_get_handle(handle, "_LCK", &temp))) {
>> +    if (ACPI_SUCCESS(acpi_get_handle(handle, "_LCK", &not_used))) {
>>           arg_list.count = 1;
>>           arg_list.pointer = &arg;
>>           arg.type = ACPI_TYPE_INTEGER;
>> @@ -161,18 +148,162 @@ 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)
>> +        if (status == AE_NOT_FOUND) {
>> +            return -ENODEV;
>> +        } else {
>>               acpi_handle_warn(handle, "Eject failed\n");
>> +            return -EIO;
>> +        }
>> +    }
>> +    return 0;
>> +}
>> +
>> +static void acpi_bus_device_eject(void *context)
>> +{
>> +    acpi_handle handle = context;
>> +    struct acpi_device *device = NULL;
>> +    struct acpi_scan_handler *handler;
>> +    u32 ost_source = ACPI_NOTIFY_EJECT_REQUEST;
>> +    u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
>> +
>> +    mutex_lock(&acpi_scan_lock);
>>
>> -        /* Tell the firmware the hot-remove operation has failed. */
>> -        acpi_evaluate_hotplug_ost(handle, ej_event->event,
>> -                      ost_code, NULL);
>> +    acpi_bus_get_device(handle, &device);
>> +    if (!device)
>> +        goto out;
>> +
>> +    handler = device->handler;
>> +    if (!handler || !handler->hotplug.enabled) {
>> +        ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
>> +        goto out;
>>       }
>> +    acpi_evaluate_hotplug_ost(handle, ACPI_NOTIFY_EJECT_REQUEST,
>> +                  ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
>
>> +    if (handler->hotplug.uevents)
>> +        kobject_uevent(&device->dev.kobj, KOBJ_OFFLINE);
>> +
>> +    if (handler->hotplug.autoeject) {
>> +        int error;
>> +
>> +        ost_source = ACPI_OST_EC_OSPM_EJECT;
>> +        get_device(&device->dev);
>> +        error = acpi_scan_hot_remove(device);
>> +        if (!error)
>> +            ost_code = ACPI_OST_SC_SUCCESS;
>> +    } else {
>> +        device->flags.eject_pending = true;
>> +        goto out_unlock;
>> +    }
>
> I want you to change the order of uevents and autoeject.
> When user caught OFFLINE event, user thinks devices were removed.
> But it is not guaranteed in this code since acpi_scan_hot_remove() may
> be running.
>
>> +
>> + out:
>> +    acpi_evaluate_hotplug_ost(handle, ost_source, ost_code, NULL);
>> +
>> + out_unlock:
>> +    mutex_unlock(&acpi_scan_lock);
>> +}
>> +

>> +static void acpi_scan_bus_device_check(acpi_handle handle, u32 ost_source)
>> +{
>> +    struct acpi_device *device = NULL;
>> +    u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
>> +    int error;
>> +
>> +    mutex_lock(&acpi_scan_lock);
>> +
>> +    acpi_bus_get_device(handle, &device);
>> +    if (device) {
>> +        dev_warn(&device->dev, "Attempt to re-insert\n");
>> +        goto out;
>> +    }
>> +    acpi_evaluate_hotplug_ost(handle, ost_source,
>> +                  ACPI_OST_SC_INSERT_IN_PROGRESS, NULL);
>> +    ost_source = ACPI_OST_EC_OSPM_INSERTION;
>> +    error = acpi_bus_scan(handle);
>> +    if (error) {
>> +        acpi_handle_warn(handle, "Namespace scan failure\n");
>> +        goto out;
>> +    }
>> +    error = acpi_bus_get_device(handle, &device);
>> +    if (error) {
>> +        acpi_handle_warn(handle, "Missing device node object\n");
>> +        goto out;
>> +    }
>> +    ost_code = ACPI_OST_SC_SUCCESS;
>> +    if (device->handler && device->handler->hotplug.uevents)
>> +        kobject_uevent(&device->dev.kobj, KOBJ_ONLINE);
>>
>>    out:
>> +    acpi_evaluate_hotplug_ost(handle, ost_source, ost_code, NULL);
>> +    mutex_unlock(&acpi_scan_lock);
>> +}

Why don't you check _STA method in acpi_scan_bus_device_check()?
When hot adding new device, we must check _STA method of the device.

Thanks,
Yasuaki Ishimatsu

>> +
>> +static void acpi_scan_bus_check(void *context)
>> +{
>> +    acpi_scan_bus_device_check((acpi_handle)context,
>> +                   ACPI_NOTIFY_BUS_CHECK);
>> +}
>> +
>> +static void acpi_scan_device_check(void *context)
>> +{
>> +    acpi_scan_bus_device_check((acpi_handle)context,
>> +                   ACPI_NOTIFY_DEVICE_CHECK);
>> +}
>> +
>> +static void acpi_hotplug_notify_cb(acpi_handle handle, u32 type, void *not_used)
>> +{
>> +    acpi_osd_exec_callback callback;
>> +    acpi_status status;
>> +
>> +    switch (type) {
>> +    case ACPI_NOTIFY_BUS_CHECK:
>> +        acpi_handle_debug(handle, "ACPI_NOTIFY_BUS_CHECK event\n");
>> +        callback = acpi_scan_bus_check;
>> +        break;
>> +    case ACPI_NOTIFY_DEVICE_CHECK:
>> +        acpi_handle_debug(handle, "ACPI_NOTIFY_DEVICE_CHECK event\n");
>> +        callback = acpi_scan_device_check;
>> +        break;
>> +    case ACPI_NOTIFY_EJECT_REQUEST:
>> +        acpi_handle_debug(handle, "ACPI_NOTIFY_EJECT_REQUEST event\n");
>> +        callback = acpi_bus_device_eject;
>> +        break;
>> +    default:
>> +        /* non-hotplug event; possibly handled by other handler */
>> +        return;
>> +    }
>> +    status = acpi_os_hotplug_execute(callback, handle);
>> +    if (ACPI_FAILURE(status))
>> +        acpi_evaluate_hotplug_ost(handle, type,
>> +                      ACPI_OST_SC_NON_SPECIFIC_FAILURE,
>> +                      NULL);
>> +}
>> +
>> +/**
>> + * acpi_bus_hot_remove_device: hot-remove a device and its children
>> + * @context: struct acpi_eject_event pointer (freed in this func)
>> + *
>> + * Hot-remove a device and its children. This function frees up the
>> + * memory space passed by arg context, so that the caller may call
>> + * this function asynchronously through acpi_os_hotplug_execute().
>> + */
>> +void acpi_bus_hot_remove_device(void *context)
>> +{
>> +    struct acpi_eject_event *ej_event = context;
>> +    struct acpi_device *device = ej_event->device;
>> +    acpi_handle handle = device->handle;
>> +    u32 ost_code = ACPI_OST_SC_SUCCESS;
>> +    int error;
>> +
>> +    mutex_lock(&acpi_scan_lock);
>> +
>> +    error = acpi_scan_hot_remove(device);
>> +    if (error)
>> +        ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
>> +
>> +    acpi_evaluate_hotplug_ost(handle, ej_event->event, ost_code, NULL);
>> +
>>       mutex_unlock(&acpi_scan_lock);
>>       kfree(context);
>> -    return;
>>   }
>>   EXPORT_SYMBOL(acpi_bus_hot_remove_device);
>>
>> @@ -206,50 +337,48 @@ static ssize_t
>>   acpi_eject_store(struct device *d, struct device_attribute *attr,
>>           const char *buf, size_t count)
>>   {
>> -    int ret = count;
>> -    acpi_status status;
>> -    acpi_object_type type = 0;
>>       struct acpi_device *acpi_device = to_acpi_device(d);
>> -    struct acpi_eject_event *ej_event;
>> +    acpi_object_type not_used;
>> +    acpi_status status;
>> +    u32 ost_source;
>> +    u32 ost_code;
>> +    int ret;
>>
>> -    if ((!count) || (buf[0] != '1')) {
>> +    if (!count || buf[0] != '1')
>>           return -EINVAL;
>> -    }
>> -    if (!acpi_device->driver && !acpi_device->handler) {
>> -        ret = -ENODEV;
>> -        goto err;
>> -    }
>> -    status = acpi_get_type(acpi_device->handle, &type);
>> -    if (ACPI_FAILURE(status) || (!acpi_device->flags.ejectable)) {
>> -        ret = -ENODEV;
>> -        goto err;
>> -    }
>>
>> -    ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
>> -    if (!ej_event) {
>> -        ret = -ENOMEM;
>> -        goto err;
>> -    }
>> +    if ((!acpi_device->handler || !acpi_device->handler->hotplug.enabled)
>> +        && !acpi_device->driver)
>> +        return -ENODEV;
>> +
>> +    status = acpi_get_type(acpi_device->handle, &not_used);
>> +    if (ACPI_FAILURE(status) || !acpi_device->flags.ejectable)
>> +        return -ENODEV;
>> +
>> +    mutex_lock(&acpi_scan_lock);
>>
>> -    get_device(&acpi_device->dev);
>> -    ej_event->device = acpi_device;
>>       if (acpi_device->flags.eject_pending) {
>> -        /* event originated from ACPI eject notification */
>> -        ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
>> +        /* ACPI eject notification event. */
>> +        ost_source = ACPI_NOTIFY_EJECT_REQUEST;
>>           acpi_device->flags.eject_pending = 0;
>>       } else {
>> -        /* event originated from user */
>> -        ej_event->event = ACPI_OST_EC_OSPM_EJECT;
>> -        (void) acpi_evaluate_hotplug_ost(acpi_device->handle,
>> -            ej_event->event, ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
>> +        /* Eject initiated by user space. */
>> +        ost_source = ACPI_OST_EC_OSPM_EJECT;
>>       }
>> -
>
>> -    status = acpi_os_hotplug_execute(acpi_bus_hot_remove_device, ej_event);
>> -    if (ACPI_FAILURE(status)) {
>> -        put_device(&acpi_device->dev);
>> -        kfree(ej_event);
>> +    acpi_evaluate_hotplug_ost(acpi_device->handle, ost_source,
>> +                  ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
>> +    get_device(&acpi_device->dev);
>> +    ret = acpi_scan_hot_remove(acpi_device);
>
> Why don't you use acpi_os_hotplug_execute()? Do you have some reason?
>
> Thanks,
> Yasuaki Ishimatsu
>
>> +    if (ret) {
>> +        ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
>> +    } else {
>> +        ost_code = ACPI_OST_SC_SUCCESS;
>> +        ret = count;
>>       }
>> -err:
>> +    acpi_evaluate_hotplug_ost(acpi_device->handle, ACPI_OST_EC_OSPM_EJECT,
>> +                  ost_code, NULL);
>> +
>> +    mutex_unlock(&acpi_scan_lock);
>>       return ret;
>>   }
>>
>> @@ -1548,6 +1677,30 @@ static struct acpi_scan_handler *acpi_sc
>>       return NULL;
>>   }
>>
>> +static void acpi_scan_init_hotplug(acpi_handle handle)
>> +{
>> +    struct acpi_device_info *info;
>> +    struct acpi_scan_handler *handler;
>> +
>> +    if (ACPI_FAILURE(acpi_get_object_info(handle, &info)))
>> +        return;
>> +
>> +    if (!(info->valid & ACPI_VALID_HID)) {
>> +        kfree(info);
>> +        return;
>> +    }
>> +
>> +    /*
>> +     * This relies on the fact that acpi_install_notify_handler() will not
>> +     * install the same notify handler routine twice for the same handle.
>> +     */
>> +    handler = acpi_scan_match_handler(info->hardware_id.string, NULL);
>> +    kfree(info);
>> +    if (handler && handler->hotplug.enabled)
>> +        acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
>> +                        acpi_hotplug_notify_cb, NULL);
>> +}
>> +
>>   static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
>>                         void *not_used, void **return_value)
>>   {
>> @@ -1570,6 +1723,8 @@ static acpi_status acpi_bus_check_add(ac
>>           return AE_OK;
>>       }
>>
>> +    acpi_scan_init_hotplug(handle);
>> +
>>       if (!(sta & ACPI_STA_DEVICE_PRESENT) &&
>>           !(sta & ACPI_STA_DEVICE_FUNCTIONING)) {
>>           struct acpi_device_wakeup wakeup;
>>
>
>
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