ACPI: improve acpi_extract_package() utility

The current version requires one to know the size of the package
a priori; this is almost impossible if the package is composed of
strings of variable length.  This change allows the utility to
allocate a buffer of the proper size if asked.

Signed-off-by: Al Stone <al.stone@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index 552248b0005b01a241ab511e52eef08a1c15d244..fc2cd328408053dfaa37eceb227de974b2796bf6 100644 (file)
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -169,11 +169,20 @@ acpi_extract_package(union acpi_object *package,
        /*
         * Validate output buffer.
         */
-       if (buffer->length < size_required) {
+       if (buffer->length == ACPI_ALLOCATE_BUFFER) {
+               buffer->pointer = ACPI_ALLOCATE(size_required);
+               if (!buffer->pointer)
+                       return AE_NO_MEMORY;
                buffer->length = size_required;
-               return AE_BUFFER_OVERFLOW;
-       } else if (buffer->length != size_required || !buffer->pointer) {
-               return AE_BAD_PARAMETER;
+               memset(buffer->pointer, 0, size_required);
+       } else {
+               if (buffer->length < size_required) {
+                       buffer->length = size_required;
+                       return AE_BUFFER_OVERFLOW;
+               } else if (buffer->length != size_required ||
+                          !buffer->pointer) {
+                       return AE_BAD_PARAMETER;
+               }
        }
 
        head = buffer->pointer;