ACPICA: Optimize buffer allocation procedure

Eliminate duplicate code.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 28 insertions, 25 deletions

diff --git a/drivers/acpi/utilities/utalloc.c b/drivers/acpi/utilities/utalloc.c
index 7dcb67e0b215..241c535c1753 100644
--- a/drivers/acpi/utilities/utalloc.c
+++ b/drivers/acpi/utilities/utalloc.c
@@ -232,7 +232,7 @@ acpi_status acpi_ut_validate_buffer(struct acpi_buffer * buffer)
  * RETURN:      Status
  *
  * DESCRIPTION: Validate that the buffer is of the required length or
- *              allocate a new buffer.  Returned buffer is always zeroed.
+ *              allocate a new buffer. Returned buffer is always zeroed.
  *
  ******************************************************************************/
 
@@ -240,7 +240,7 @@ acpi_status
 acpi_ut_initialize_buffer(struct acpi_buffer * buffer,
                           acpi_size required_length)
 {
-        acpi_status status = AE_OK;
+        acpi_size input_buffer_length;
 
         /* Parameter validation */
 
@@ -248,55 +248,58 @@ acpi_ut_initialize_buffer(struct acpi_buffer * buffer,
                 return (AE_BAD_PARAMETER);
         }
 
-        switch (buffer->length) {
+        /*
+         * Buffer->Length is used as both an input and output parameter. Get the
+         * input actual length and set the output required buffer length.
+         */
+        input_buffer_length = buffer->length;
+        buffer->length = required_length;
+
+        /*
+         * The input buffer length contains the actual buffer length, or the type
+         * of buffer to be allocated by this routine.
+         */
+        switch (input_buffer_length) {
         case ACPI_NO_BUFFER:
 
-                /* Set the exception and returned the required length */
+                /* Return the exception (and the required buffer length) */
 
-                status = AE_BUFFER_OVERFLOW;
-                break;
+                return (AE_BUFFER_OVERFLOW);
 
         case ACPI_ALLOCATE_BUFFER:
 
                 /* Allocate a new buffer */
 
                 buffer->pointer = acpi_os_allocate(required_length);
-                if (!buffer->pointer) {
-                        return (AE_NO_MEMORY);
-                }
-
-                /* Clear the buffer */
-
-                ACPI_MEMSET(buffer->pointer, 0, required_length);
                 break;
 
         case ACPI_ALLOCATE_LOCAL_BUFFER:
 
                 /* Allocate a new buffer with local interface to allow tracking */
 
-                buffer->pointer = ACPI_ALLOCATE_ZEROED(required_length);
-                if (!buffer->pointer) {
-                        return (AE_NO_MEMORY);
-                }
+                buffer->pointer = ACPI_ALLOCATE(required_length);
                 break;
 
         default:
 
                 /* Existing buffer: Validate the size of the buffer */
 
-                if (buffer->length < required_length) {
-                        status = AE_BUFFER_OVERFLOW;
-                        break;
+                if (input_buffer_length < required_length) {
+                        return (AE_BUFFER_OVERFLOW);
                 }
+                break;
+        }
 
-                /* Clear the buffer */
+        /* Validate allocation from above or input buffer pointer */
 
-                ACPI_MEMSET(buffer->pointer, 0, required_length);
-                break;
+        if (!buffer->pointer) {
+                return (AE_NO_MEMORY);
         }
 
-        buffer->length = required_length;
-        return (status);
+        /* Have a valid buffer, clear it */
+
+        ACPI_MEMSET(buffer->pointer, 0, required_length);
+        return (AE_OK);
 }
 
 #ifdef NOT_USED_BY_LINUX