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>

1 files changed, 13 insertions, 4 deletions

diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index 552248b0005b..fc2cd3284080 100644
--- 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;