[PATCH] drm/amd/display: fix usage of DC_FPU_{BEGIN,END} with PREEMPT_RT

[Bert Karwatzki]

On PREEMPT_RT kernels kvzalloc_obj() can sleep because spin_lock is
converted to rt_mutex. dc_create_plane_state() can be called while
inside an FPU-guarded region, resuling in "scheduling while atomic"
errors on PREEMPT_RT kernels.
 Fix this by calling kvzalloc_obj() with DC_RUN_WITH_PREEMPTION_ENABLED().
Also fix the error path in dc_create_stream_for_sink().

Fixes: 3539437f354b ("drm/amd/display: Move FPU Guards From DML To DC - Part 1")
Link: https://lore.kernel.org/lkml/20260723123449.6494-1-spasswolf@xxxxxx/

Signed-off-by: Bert Karwatzki <spasswolf@xxxxxx>
---
 drivers/gpu/drm/amd/display/dc/core/dc_stream.c  | 5 +++--
 drivers/gpu/drm/amd/display/dc/core/dc_surface.c | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
index dbc12640b01c..4ac835777b58 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
@@ -233,8 +233,9 @@ struct dc_stream_state *dc_create_stream_for_sink(
 
 fail:
 	if (stream) {
-		kfree(stream->update_scratch);
-		kfree(stream);
+		if (stream->update_scratch)
+			DC_RUN_WITH_PREEMPTION_ENABLED(kfree(stream->update_scratch));
+		DC_RUN_WITH_PREEMPTION_ENABLED(kfree(stream));
 	}
 
 	return NULL;
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_surface.c b/drivers/gpu/drm/amd/display/dc/core/dc_surface.c
index 88e825a6582c..d5c6427796b6 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_surface.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_surface.c
@@ -85,8 +85,8 @@ uint8_t  dc_plane_get_pipe_mask(struct dc_state *dc_state, const struct dc_plane
  ******************************************************************************/
 struct dc_plane_state *dc_create_plane_state(const struct dc *dc)
 {
-	struct dc_plane_state *plane_state = kvzalloc_obj(*plane_state,
-							  GFP_ATOMIC);
+	struct dc_plane_state *plane_state;
+	DC_RUN_WITH_PREEMPTION_ENABLED(plane_state = kvzalloc_obj(*plane_state, GFP_ATOMIC));
 
 	if (NULL == plane_state)
 		return NULL;
-- 
2.53.0