On Sun, Nov 18, 2012 at 10:12:52PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> Currently, the ACPI handles of devices are initialized from within
> device_add(), by acpi_bind_one() called from acpi_platform_notify()
> which first uses the .find_device() routine provided by the device's
> bus type to find the matching device node in the ACPI namespace.
> This is a source of some computational overhead and, moreover, the
> correctness of the result depends on the implementation of
> .find_device() which is known to fail occasionally for some bus types
> (e.g. PCI). In some cases, however, the corresponding ACPI device
> node is known already before calling device_add() for the given
> struct device object and the whole .find_device() dance in
> acpi_platform_notify() is then simply unnecessary.
>
> For this reason, make it possible to initialize the ACPI handles of
> devices before calling device_add() for them. Modify
> acpi_platform_notify() to call acpi_bind_one() in advance to check
> the device's existing ACPI handle and skip the .find_device()
> search if that is successful. Change acpi_bind_one() accordingly.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/acpi/glue.c | 42 +++++++++++++++++++++++++++++++++---------
> 1 file changed, 33 insertions(+), 9 deletions(-)
>
> Index: linux/drivers/acpi/glue.c
> ===================================================================
> --- linux.orig/drivers/acpi/glue.c
> +++ linux/drivers/acpi/glue.c
> @@ -135,41 +135,54 @@ static int acpi_bind_one(struct device *
> int retval = -EINVAL;
>
> if (dev->acpi_handle) {
> - dev_warn(dev, "Drivers changed 'acpi_handle'\n");
> - return -EINVAL;
> + if (handle) {
> + dev_warn(dev, "ACPI handle is already set\n");
> + return -EINVAL;
> + } else {
> + handle = dev->acpi_handle;
> + }
> }
> + if (!handle)
> + return -EINVAL;
>
> get_device(dev);
> status = acpi_bus_get_device(handle, &acpi_dev);
> if (ACPI_FAILURE(status))
> goto err;
>
> - physical_node = kzalloc(sizeof(struct acpi_device_physical_node),
> - GFP_KERNEL);
> + physical_node = kzalloc(sizeof(*physical_node), GFP_KERNEL);
Here we allocate memory for the physical node...
> if (!physical_node) {
> retval = -ENOMEM;
> goto err;
> }
>
> mutex_lock(&acpi_dev->physical_node_lock);
> +
> + /* Sanity check. */
> + list_for_each_entry(physical_node, &acpi_dev->physical_node_list, node)
.. and overwrite it here ;-)
Maybe using a different variable for the sanity check?
I've changed the SPI/I2C patches to use this as well and they got a lot
smaller as we don't have to do the .find_device() magic.
Once you have fixed the above, you can add my
Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
to these two patches, if you like.
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