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    SubjectRe: [PATCH v2 3/7] ACPI: Add _OST support for sysfs eject
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    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);




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