ACPICA: Clarify ACPI_FREE_BUFFER usage.

Add a comment to clarify reason for using ACPI_FREE_BUFFER directly
instead of ACPI_FREE.

In addition to that, change one instance in which ACPI_FREE_BUFFER()
should be used instead of ACPI_FREE().

[rjw: Subject and changelog]
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 8 insertions, 4 deletions

diff --git a/drivers/acpi/acpica/nsxfeval.c b/drivers/acpi/acpica/nsxfeval.c
index a6e3bca48567..ce2a84575a36 100644
--- a/drivers/acpi/acpica/nsxfeval.c
+++ b/drivers/acpi/acpica/nsxfeval.c
@@ -139,7 +139,7 @@ acpi_evaluate_object_typed(acpi_handle handle,
 
                 /* Caller used ACPI_ALLOCATE_BUFFER, free the return buffer */
 
-                ACPI_FREE(return_buffer->pointer);
+                ACPI_FREE_BUFFER(*return_buffer);
                 return_buffer->pointer = NULL;
         }
 
diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
index 63909d9c2f7a..0bb23e6bce43 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -919,9 +919,13 @@ struct acpi_buffer {
         void *pointer;          /* pointer to buffer */
 };
 
-/* Free a buffer created in an struct acpi_buffer via ACPI_ALLOCATE_LOCAL_BUFFER */
-
-#define ACPI_FREE_BUFFER(b)         ACPI_FREE(b.pointer)
+/*
+ * Free a buffer created in an struct acpi_buffer via ACPI_ALLOCATE_BUFFER.
+ * Note: We use acpi_os_free here because acpi_os_allocate was used to allocate
+ * the buffer. This purposefully bypasses the internal allocation tracking
+ * mechanism (if it is enabled).
+ */
+#define ACPI_FREE_BUFFER(b)         acpi_os_free((b).pointer)
 
 /*
  * name_type for acpi_get_name