[PATCH 5/9] staging: media: atomisp: fix stack overflow in init_pipe_defaults()

[Arnd Bergmann]

When building with clang, multiple copies of the structures to be
initialized are passed around on the stack and copied locally, using an
insane amount of stack space:

drivers/staging/media/atomisp/pci/sh_css.c:2371:1: error: stack frame size of 26864 bytes in function 'create_pipe' [-Werror,-Wframe-larger-than=]

Use constantly-allocated variables plus an explicit memcpy()
to avoid that.

Fixes: 6dc9a2568f84 ("media: atomisp: convert default struct values to use compound-literals with designated initializers")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 drivers/staging/media/atomisp/pci/sh_css.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/media/atomisp/pci/sh_css.c b/drivers/staging/media/atomisp/pci/sh_css.c
index e91c6029c651..1e8b9d637116 100644
--- a/drivers/staging/media/atomisp/pci/sh_css.c
+++ b/drivers/staging/media/atomisp/pci/sh_css.c
@@ -2264,6 +2264,12 @@ static enum ia_css_err
 init_pipe_defaults(enum ia_css_pipe_mode mode,
 		   struct ia_css_pipe *pipe,
 		   bool copy_pipe) {
+	static const struct ia_css_pipe default_pipe = IA_CSS_DEFAULT_PIPE;
+	static const struct ia_css_preview_settings preview = IA_CSS_DEFAULT_PREVIEW_SETTINGS;
+	static const struct ia_css_capture_settings capture = IA_CSS_DEFAULT_CAPTURE_SETTINGS;
+	static const struct ia_css_video_settings video = IA_CSS_DEFAULT_VIDEO_SETTINGS;
+	static const struct ia_css_yuvpp_settings yuvpp = IA_CSS_DEFAULT_YUVPP_SETTINGS;
+
 	if (!pipe)
 	{
 		IA_CSS_ERROR("NULL pipe parameter");
@@ -2271,14 +2277,14 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
 	}
 
 	/* Initialize pipe to pre-defined defaults */
-	*pipe = IA_CSS_DEFAULT_PIPE;
+	memcpy(pipe, &default_pipe, sizeof(default_pipe));
 
 	/* TODO: JB should not be needed, but temporary backward reference */
 	switch (mode)
 	{
 	case IA_CSS_PIPE_MODE_PREVIEW:
 		pipe->mode = IA_CSS_PIPE_ID_PREVIEW;
-		pipe->pipe_settings.preview = IA_CSS_DEFAULT_PREVIEW_SETTINGS;
+		memcpy(&pipe->pipe_settings.preview, &preview, sizeof(preview));
 		break;
 	case IA_CSS_PIPE_MODE_CAPTURE:
 		if (copy_pipe) {
@@ -2286,11 +2292,11 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
 		} else {
 			pipe->mode = IA_CSS_PIPE_ID_CAPTURE;
 		}
-		pipe->pipe_settings.capture = IA_CSS_DEFAULT_CAPTURE_SETTINGS;
+		memcpy(&pipe->pipe_settings.capture, &capture, sizeof(capture));
 		break;
 	case IA_CSS_PIPE_MODE_VIDEO:
 		pipe->mode = IA_CSS_PIPE_ID_VIDEO;
-		pipe->pipe_settings.video = IA_CSS_DEFAULT_VIDEO_SETTINGS;
+		memcpy(&pipe->pipe_settings.video, &video, sizeof(video));
 		break;
 	case IA_CSS_PIPE_MODE_ACC:
 		pipe->mode = IA_CSS_PIPE_ID_ACC;
@@ -2300,7 +2306,7 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
 		break;
 	case IA_CSS_PIPE_MODE_YUVPP:
 		pipe->mode = IA_CSS_PIPE_ID_YUVPP;
-		pipe->pipe_settings.yuvpp = IA_CSS_DEFAULT_YUVPP_SETTINGS;
+		memcpy(&pipe->pipe_settings.yuvpp, &yuvpp, sizeof(yuvpp));
 		break;
 	default:
 		return IA_CSS_ERR_INVALID_ARGUMENTS;
-- 
2.26.2