1 files changed, 7 insertions, 0 deletions

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 8971370bfb16..b157b46cc9a6 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -17,8 +17,10 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  */
 
+#include <linux/sched/task_stack.h>
 #include <linux/scatterlist.h>
 #include <linux/dma-mapping.h>
+#include <linux/sched/task.h>
 #include <linux/stacktrace.h>
 #include <linux/dma-debug.h>
 #include <linux/spinlock.h>
@@ -1155,6 +1157,11 @@ static void check_unmap(struct dma_debug_entry *ref)
                            dir2name[ref->direction]);
         }
 
+        /*
+         * Drivers should use dma_mapping_error() to check the returned
+         * addresses of dma_map_single() and dma_map_page().
+         * If not, print this warning message. See Documentation/DMA-API.txt.
+         */
         if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
                 err_printk(ref->dev, entry,
                            "DMA-API: device driver failed to check map error"