[ 92/98] ACPI: Rework acpi_get_child() to be more efficient

Greg Kroah-Hartman
2013-03-26T22:50:08Z

From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

commit 33f767d767e9a684e9cd60704d4c049a2014c8d5 upstream.

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>
Cc: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/acpi/glue.c | 33 ++++++++++++---------------------
1 file changed, 12 insertions(+), 21 deletions(-)

--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -95,40 +95,31 @@ static int acpi_find_bridge_device(struc
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)