Re: [PATCH v2 3/7] ACPI: Add _OST support for sysfs eject

[Shuah Khan <shuahkhan@gmail.com>]

On Tue, 2012-05-08 at 14:12 -0600, Toshi Kani wrote:
> Changed acpi_bus_hot_remove_device() to support _OST. This function is
> also changed to global so that it can be called from hotplug notify
> handlers to perform hot-remove operation.
> 
> Changed acpi_eject_store(), which is the sysfs eject handler. It checks
> eject_pending to see if the request was originated from ACPI eject
> notification. If not, it calls _OST(0x103,84,) per Figure 6-37 in ACPI
> 5.0 spec.
> 
> Added eject_pending bit to acpi_device_flags. This bit is set when the
> kernel has received an ACPI eject notification, but does not initiate
> its hot-remove operation by itself.
> 
> Added struct acpi_eject_event. This structure is used to pass extended
> information to acpi_bus_hot_remove_device(), which has a single argument
> to support asynchronous call.
> 
> Added macro definitions of _OST source events and status codes.
> Also renamed OSC_SB_CPUHP_OST_SUPPORT to OSC_SB_HOTPLUG_OST_SUPPORT
> since this _OSC bit is not specific to CPU hotplug. This bit is
> defined in Table 6-147 of ACPI 5.0 as follows.

I am confused. This patch adds lot of new code that is for _OST handling
without CONFIG_ACPI_HOTPLUG_OST check. Is this intended? Doesn't jive
with the intent communicated in the [PATCH v2 0/7] introduction.

Could you please walk though the steps on what happens with this code on
a system that doesn't enable _OST and doesn't support _OST. That will
help me understand how this code would behave on a system that doesn't
support _OST.

> 
>   Bits:       3
>   Field Name: Insertion / Ejection _OST Processing Support
>   Definition: This bit is set if OSPM will evaluate the _OST
>               object defined under a device when processing
>               insertion and ejection source event codes.
> 
> Signed-off-by: Toshi Kani <toshi.kani@hp.com>
> ---
>  drivers/acpi/scan.c     |   58 +++++++++++++++++++++++++++++++++++++++-------
>  include/acpi/acpi_bus.h |    9 ++++++-
>  include/linux/acpi.h    |   31 ++++++++++++++++++++++++-
>  3 files changed, 87 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 7417267..84ba717 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -83,19 +83,29 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha
>  }
>  static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);
>  
> -static void acpi_bus_hot_remove_device(void *context)
> +/*
> + * 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 = (struct acpi_eject_event *) context;
>  	struct acpi_device *device;
> -	acpi_handle handle = context;
> +	acpi_handle handle = ej_event->handle;
>  	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 */
>  
>  	if (acpi_bus_get_device(handle, &device))
> -		return;
> +		goto err_out;
>  
>  	if (!device)
> -		return;
> +		goto err_out;
>  
>  	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
>  		"Hot-removing device %s...\n", dev_name(&device->dev)));
> @@ -103,7 +113,7 @@ static void acpi_bus_hot_remove_device(void *context)
>  	if (acpi_bus_trim(device, 1)) {
>  		printk(KERN_ERR PREFIX
>  				"Removing device failed\n");
> -		return;
> +		goto err_out;
>  	}
>  
>  	/* power off device */
> @@ -129,10 +139,21 @@ static void acpi_bus_hot_remove_device(void *context)
>  	 * TBD: _EJD support.
>  	 */
>  	status = acpi_evaluate_object(handle, "_EJ0", &arg_list, NULL);
> -	if (ACPI_FAILURE(status))
> -		printk(KERN_WARNING PREFIX
> -				"Eject device failed\n");
> +	if (ACPI_FAILURE(status)) {
> +		if (status != AE_NOT_FOUND)
> +			printk(KERN_WARNING PREFIX
> +					"Eject device failed\n");
> +		goto err_out;
> +	}
> +
> +	kfree(context);

Could please explain why this kfree is needed now. Can context be
free'ed here safely?

> +	return;
>  
> +err_out:
> +	/* Inform firmware the hot-remove operation has completed w/ error */
> +	(void) acpi_evaluate_hotplug_ost(handle,
> +				ej_event->event, ost_code, NULL);
> +	kfree(context);

Same question as above.

>  	return;
>  }
>  
> @@ -144,6 +165,7 @@ acpi_eject_store(struct device *d, struct device_attribute *attr,
>  	acpi_status status;
>  	acpi_object_type type = 0;
>  	struct acpi_device *acpi_device = to_acpi_device(d);
> +	struct acpi_eject_event *ej_event;
>  
>  	if ((!count) || (buf[0] != '1')) {
>  		return -EINVAL;
> @@ -160,7 +182,25 @@ acpi_eject_store(struct device *d, struct device_attribute *attr,
>  		goto err;
>  	}
>  
> -	acpi_os_hotplug_execute(acpi_bus_hot_remove_device, acpi_device->handle);
> +	ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
> +	if (!ej_event) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	ej_event->handle = acpi_device->handle;
> +	if (acpi_device->flags.eject_pending) {
> +		/* event originated from ACPI eject notification */
> +		ej_event->event = 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(ej_event->handle,
> +			ej_event->event, ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
> +	}
> +
> +	acpi_os_hotplug_execute(acpi_bus_hot_remove_device, (void *)ej_event);
>  err:
>  	return ret;
>  }
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 7309113..b836800 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -151,7 +151,8 @@ struct acpi_device_flags {
>  	u32 suprise_removal_ok:1;
>  	u32 power_manageable:1;
>  	u32 performance_manageable:1;
> -	u32 reserved:24;
> +	u32 eject_pending:1;
> +	u32 reserved:23;
>  };
>  
>  /* File System */
> @@ -303,6 +304,11 @@ struct acpi_bus_event {
>  	u32 data;
>  };
>  
> +struct acpi_eject_event {
> +	acpi_handle	handle;
> +	u32		event;
> +};
> +
>  extern struct kobject *acpi_kobj;
>  extern int acpi_bus_generate_netlink_event(const char*, const char*, u8, int);
>  void acpi_bus_private_data_handler(acpi_handle, void *);
> @@ -340,6 +346,7 @@ int acpi_bus_register_driver(struct acpi_driver *driver);
>  void acpi_bus_unregister_driver(struct acpi_driver *driver);
>  int acpi_bus_add(struct acpi_device **child, struct acpi_device *parent,
>  		 acpi_handle handle, int type);
> +void acpi_bus_hot_remove_device(void *context);
>  int acpi_bus_trim(struct acpi_device *start, int rmdevice);
>  int acpi_bus_start(struct acpi_device *device);
>  acpi_status acpi_bus_get_ejd(acpi_handle handle, acpi_handle * ejd);
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index f421dd8..a4b1d3d 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -277,7 +277,7 @@ acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context);
>  #define OSC_SB_PAD_SUPPORT		1
>  #define OSC_SB_PPC_OST_SUPPORT		2
>  #define OSC_SB_PR3_SUPPORT		4
> -#define OSC_SB_CPUHP_OST_SUPPORT	8
> +#define OSC_SB_HOTPLUG_OST_SUPPORT	8
>  #define OSC_SB_APEI_SUPPORT		16
>  
>  extern bool osc_sb_apei_support_acked;
> @@ -309,6 +309,35 @@ extern bool osc_sb_apei_support_acked;
>  
>  extern acpi_status acpi_pci_osc_control_set(acpi_handle handle,
>  					     u32 *mask, u32 req);
> +
> +/* _OST Source Event Code (OSPM Action) */
> +#define ACPI_OST_EC_OSPM_SHUTDOWN		0x100
> +#define ACPI_OST_EC_OSPM_EJECT			0x103
> +#define ACPI_OST_EC_OSPM_INSERTION		0x200
> +
> +/* _OST General Processing Status Code */
> +#define ACPI_OST_SC_SUCCESS			0x0
> +#define ACPI_OST_SC_NON_SPECIFIC_FAILURE	0x1
> +#define ACPI_OST_SC_UNRECOGNIZED_NOTIFY		0x2
> +
> +/* _OST OS Shutdown Processing (0x100) Status Code */
> +#define ACPI_OST_SC_OS_SHUTDOWN_DENIED		0x80
> +#define ACPI_OST_SC_OS_SHUTDOWN_IN_PROGRESS	0x81
> +#define ACPI_OST_SC_OS_SHUTDOWN_COMPLETED	0x82
> +#define ACPI_OST_SC_OS_SHUTDOWN_NOT_SUPPORTED	0x83
> +
> +/* _OST Ejection Request (0x3, 0x103) Status Code */
> +#define ACPI_OST_SC_EJECT_NOT_SUPPORTED		0x80
> +#define ACPI_OST_SC_DEVICE_IN_USE		0x81
> +#define ACPI_OST_SC_DEVICE_BUSY			0x82
> +#define ACPI_OST_SC_EJECT_DEPENDENCY_BUSY	0x83
> +#define ACPI_OST_SC_EJECT_IN_PROGRESS		0x84
> +
> +/* _OST Insertion Request (0x200) Status Code */
> +#define ACPI_OST_SC_INSERT_IN_PROGRESS		0x80
> +#define ACPI_OST_SC_DRIVER_LOAD_FAILURE		0x81
> +#define ACPI_OST_SC_INSERT_NOT_SUPPORTED	0x82
> +
>  extern void acpi_early_init(void);
>  
>  extern int acpi_nvs_register(__u64 start, __u64 size);