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ACPI: Rework acpi_get_child() to be more efficient 

Observe that acpi_get_child() doesn't need to use the helper
struct acpi_find_child structure and change it to work without it.
Also, using acpi_get_object_info() to get the output of _ADR for the
given device is overkill, because that function does much more than
just evaluating _ADR (let alone the additional memory allocation
done by it).

Moreover, acpi_get_child() doesn't need to loop any more once it has
found a matching handle, so make it stop in that case.  To prevent
the results from changing, make it use do_acpi_find_child() as
a post-order callback.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2013-01-10 13:13:49 +01:00
parent 949db153b6
commit 33f767d767
1 changed files with 12 additions and 21 deletions
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33
drivers/acpi/glue.c
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@ -95,40 +95,31 @@ static int acpi_find_bridge_device(struct device *dev, acpi_handle * handle)
return ret;
}
/* Get device's handler per its address under its parent */
struct acpi_find_child {
acpi_handle handle;
u64 address;
};
static acpi_status
do_acpi_find_child(acpi_handle handle, u32 lvl, void *context, void **rv)
static acpi_status do_acpi_find_child(acpi_handle handle, u32 lvl_not_used,
void *addr_p, void **ret_p)
{
unsigned long long addr;
acpi_status status;
struct acpi_device_info *info;
struct acpi_find_child *find = context;
status = acpi_get_object_info(handle, &info);
if (ACPI_SUCCESS(status)) {
if ((info->address == find->address)
&& (info->valid & ACPI_VALID_ADR))
find->handle = handle;
kfree(info);
status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &addr);
if (ACPI_SUCCESS(status) && addr == *((u64 *)addr_p)) {
*ret_p = handle;
return AE_CTRL_TERMINATE;
}
return AE_OK;
}
acpi_handle acpi_get_child(acpi_handle parent, u64 address)
{
struct acpi_find_child find = { NULL, address };
void *ret = NULL;
if (!parent)
return NULL;
acpi_walk_namespace(ACPI_TYPE_DEVICE, parent,
1, do_acpi_find_child, NULL, &find, NULL);
return find.handle;
}
acpi_walk_namespace(ACPI_TYPE_DEVICE, parent, 1, NULL,
do_acpi_find_child, &address, &ret);
return (acpi_handle)ret;
}
EXPORT_SYMBOL(acpi_get_child);
static int acpi_bind_one(struct device *dev, acpi_handle handle)