linux-kernel - Re: [PATCH 3/4] ACPI: Add _OST support for ACPI CPU hotplug

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Message-ID: <CAErSpo5n22TLo+U3f_zHdkZSG=e7x4bySFPWtxT+ghYyenGc6A@mail.gmail.com>
Date:	Thu, 26 Apr 2012 09:22:59 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Toshi Kani <toshi.kani@...com>
Cc:	lenb@...nel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] ACPI: Add _OST support for ACPI CPU hotplug

On Tue, Apr 10, 2012 at 4:21 PM, Toshi Kani <toshi.kani@...com> wrote:
> Changed acpi_processor_hotplug_notify() to call ACPI _OST method
> when ACPI-based CPU hotplug operation completed.
>
> Signed-off-by: Toshi Kani <toshi.kani@...com>
> ---
>  drivers/acpi/processor_driver.c |   28 ++++++++++++++++++++--------
>  1 files changed, 20 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
> index 0734086..5d9b5a8 100644
> --- a/drivers/acpi/processor_driver.c
> +++ b/drivers/acpi/processor_driver.c
> @@ -701,9 +701,9 @@ static void acpi_processor_hotplug_notify(acpi_handle handle,
>  {
>        struct acpi_processor *pr;
>        struct acpi_device *device = NULL;
> +       u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
>        int result;
>
> -
>        switch (event) {
>        case ACPI_NOTIFY_BUS_CHECK:
>        case ACPI_NOTIFY_DEVICE_CHECK:
> @@ -715,14 +715,18 @@ static void acpi_processor_hotplug_notify(acpi_handle handle,
>                if (!is_processor_present(handle))
>                        break;
>
> -               if (acpi_bus_get_device(handle, &device)) {
> -                       result = acpi_processor_device_add(handle, &device);
> -                       if (result)
> -                               printk(KERN_ERR PREFIX
> -                                           "Unable to add the device\n");
> +               if (!acpi_bus_get_device(handle, &device))
> +                       break;
> +
> +               result = acpi_processor_device_add(handle, &device);
> +               if (result) {
> +                       printk(KERN_ERR PREFIX "Unable to add the device\n");

You didn't add this problem, but since you're touching the code, I'll
point it out.  This message will look to the user like:

    ACPI: Unable to add the device

which is useless.  The user has no idea what device we're talking
about or why we can't add it, so he can't *do* anything with the
message.  Almost every printk of a constant string has this problem.
Using dev_err() instead of printk() would help a lot, as would
including the error code (result).  Of course, this would be a
separate patch that would update all the messages in the driver at the
same time.

>                        break;
>                }
> +
> +               ost_code = ACPI_OST_SC_SUCCESS;
>                break;
> +
>        case ACPI_NOTIFY_EJECT_REQUEST:
>                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
>                                  "received ACPI_NOTIFY_EJECT_REQUEST\n"));
> @@ -736,15 +740,23 @@ static void acpi_processor_hotplug_notify(acpi_handle handle,
>                if (!pr) {
>                        printk(KERN_ERR PREFIX
>                                    "Driver data is NULL, dropping EJECT\n");
> -                       return;
> +                       break;
>                }
> +
> +               /* REVISIT: update when eject is supported */
> +               ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
>                break;
> +
>        default:
>                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
>                                  "Unsupported event [0x%x]\n", event));
> -               break;
> +
> +               /* non-hotplug event; possibly handled by other handler */
> +               return;
>        }
>
> +       /* Inform firmware that the hotplug operation has completed */
> +       (void) acpi_evaluate_ost(handle, event, ost_code, NULL);
>        return;
>  }
>
> --
> 1.7.7.6
>
> --
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