drm/atomic: Make atomic iterators less surprising

Commit 669c9215afea ("drm/atomic: Make async plane update checks work as
intended, v2.") assumed incorrectly that if only 1 plane is matched in
the loop, the variables will be set to that plane. In reality we reset
them to NULL every time a new plane was iterated. This behavior is
surprising, so fix this by making the for loops only assign the
variables on a match.

When we have not added all the planes/crtc/connector to the state, and
there's a few NULL ones after the last one we iterated, te assumption
is broken that the pointers will hold the values from the last loop
iteration, which holds true for all other for_each macros we're using.
Except of course the iterator pointer itself, but that one really is
entirely internal.

Cc: Dmitry Osipenko <digetx@gmail.com>
Fixes: 669c9215afea ("drm/atomic: Make async plane update checks work as intended, v2.")
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170927083532.5756-2-maarten.lankhorst@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Dmitry Osipenko <digetx@gmail.com>

include/drm/drm_atomic.h

@@ -585,12 +585,12 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
  */
 #define for_each_oldnew_connector_in_state(__state, connector, old_connector_state, new_connector_state, __i) \
 	for ((__i) = 0;								\
-	     (__i) < (__state)->num_connector &&				\
-	     ((connector) = (__state)->connectors[__i].ptr,			\
-	     (old_connector_state) = (__state)->connectors[__i].old_state,	\
-	     (new_connector_state) = (__state)->connectors[__i].new_state, 1); 	\
-	     (__i)++)							\
-		for_each_if (connector)
+	     (__i) < (__state)->num_connector;					\
+	     (__i)++)								\
+		for_each_if ((__state)->connectors[__i].ptr &&			\
+			     ((connector) = (__state)->connectors[__i].ptr,	\
+			     (old_connector_state) = (__state)->connectors[__i].old_state,	\
+			     (new_connector_state) = (__state)->connectors[__i].new_state, 1))
 
 /**
  * for_each_old_connector_in_state - iterate over all connectors in an atomic update
@@ -606,11 +606,11 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
  */
 #define for_each_old_connector_in_state(__state, connector, old_connector_state, __i) \
 	for ((__i) = 0;								\
-	     (__i) < (__state)->num_connector &&				\
-	     ((connector) = (__state)->connectors[__i].ptr,			\
-	     (old_connector_state) = (__state)->connectors[__i].old_state, 1); 	\
-	     (__i)++)							\
-		for_each_if (connector)
+	     (__i) < (__state)->num_connector;					\
+	     (__i)++)								\
+		for_each_if ((__state)->connectors[__i].ptr &&			\
+			     ((connector) = (__state)->connectors[__i].ptr,	\
+			     (old_connector_state) = (__state)->connectors[__i].old_state, 1))
 
 /**
  * for_each_new_connector_in_state - iterate over all connectors in an atomic update
@@ -626,11 +626,11 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
  */
 #define for_each_new_connector_in_state(__state, connector, new_connector_state, __i) \
 	for ((__i) = 0;								\
-	     (__i) < (__state)->num_connector &&				\
-	     ((connector) = (__state)->connectors[__i].ptr,			\
-	     (new_connector_state) = (__state)->connectors[__i].new_state, 1); 	\
-	     (__i)++)							\
-		for_each_if (connector)
+	     (__i) < (__state)->num_connector;					\
+	     (__i)++)								\
+		for_each_if ((__state)->connectors[__i].ptr &&			\
+			     ((connector) = (__state)->connectors[__i].ptr,	\
+			     (new_connector_state) = (__state)->connectors[__i].new_state, 1))
 
 /**
  * for_each_oldnew_crtc_in_state - iterate over all CRTCs in an atomic update
@@ -646,12 +646,12 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
  */
 #define for_each_oldnew_crtc_in_state(__state, crtc, old_crtc_state, new_crtc_state, __i) \
 	for ((__i) = 0;							\
-	     (__i) < (__state)->dev->mode_config.num_crtc &&		\
-	     ((crtc) = (__state)->crtcs[__i].ptr,			\
-	     (old_crtc_state) = (__state)->crtcs[__i].old_state,	\
-	     (new_crtc_state) = (__state)->crtcs[__i].new_state, 1);	\
+	     (__i) < (__state)->dev->mode_config.num_crtc;		\
 	     (__i)++)							\
-		for_each_if (crtc)
+		for_each_if ((__state)->crtcs[__i].ptr &&		\
+			     ((crtc) = (__state)->crtcs[__i].ptr,	\
+			     (old_crtc_state) = (__state)->crtcs[__i].old_state, \
+			     (new_crtc_state) = (__state)->crtcs[__i].new_state, 1))
 
 /**
  * for_each_old_crtc_in_state - iterate over all CRTCs in an atomic update
@@ -666,11 +666,11 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
  */
 #define for_each_old_crtc_in_state(__state, crtc, old_crtc_state, __i)	\
 	for ((__i) = 0;							\
-	     (__i) < (__state)->dev->mode_config.num_crtc &&		\
-	     ((crtc) = (__state)->crtcs[__i].ptr,			\
-	     (old_crtc_state) = (__state)->crtcs[__i].old_state, 1);	\
+	     (__i) < (__state)->dev->mode_config.num_crtc;		\
 	     (__i)++)							\
-		for_each_if (crtc)
+		for_each_if ((__state)->crtcs[__i].ptr &&		\
+			     ((crtc) = (__state)->crtcs[__i].ptr,	\
+			     (old_crtc_state) = (__state)->crtcs[__i].old_state, 1))
 
 /**
  * for_each_new_crtc_in_state - iterate over all CRTCs in an atomic update
@@ -685,11 +685,11 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
  */
 #define for_each_new_crtc_in_state(__state, crtc, new_crtc_state, __i)	\
 	for ((__i) = 0;							\
-	     (__i) < (__state)->dev->mode_config.num_crtc &&		\
-	     ((crtc) = (__state)->crtcs[__i].ptr,			\
-	     (new_crtc_state) = (__state)->crtcs[__i].new_state, 1);	\
+	     (__i) < (__state)->dev->mode_config.num_crtc;		\
 	     (__i)++)							\
-		for_each_if (crtc)
+		for_each_if ((__state)->crtcs[__i].ptr &&		\
+			     ((crtc) = (__state)->crtcs[__i].ptr,	\
+			     (new_crtc_state) = (__state)->crtcs[__i].new_state, 1))
 
 /**
  * for_each_oldnew_plane_in_state - iterate over all planes in an atomic update
@@ -705,12 +705,12 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
  */
 #define for_each_oldnew_plane_in_state(__state, plane, old_plane_state, new_plane_state, __i) \
 	for ((__i) = 0;							\
-	     (__i) < (__state)->dev->mode_config.num_total_plane &&	\
-	     ((plane) = (__state)->planes[__i].ptr,			\
-	     (old_plane_state) = (__state)->planes[__i].old_state,	\
-	     (new_plane_state) = (__state)->planes[__i].new_state, 1);	\
+	     (__i) < (__state)->dev->mode_config.num_total_plane;	\
 	     (__i)++)							\
-		for_each_if (plane)
+		for_each_if ((__state)->planes[__i].ptr &&		\
+			     ((plane) = (__state)->planes[__i].ptr,	\
+			      (old_plane_state) = (__state)->planes[__i].old_state,\
+			      (new_plane_state) = (__state)->planes[__i].new_state, 1))
 
 /**
  * for_each_old_plane_in_state - iterate over all planes in an atomic update
@@ -725,12 +725,11 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
  */
 #define for_each_old_plane_in_state(__state, plane, old_plane_state, __i) \
 	for ((__i) = 0;							\
-	     (__i) < (__state)->dev->mode_config.num_total_plane &&	\
-	     ((plane) = (__state)->planes[__i].ptr,			\
-	     (old_plane_state) = (__state)->planes[__i].old_state, 1);	\
+	     (__i) < (__state)->dev->mode_config.num_total_plane;	\
 	     (__i)++)							\
-		for_each_if (plane)
-
+		for_each_if ((__state)->planes[__i].ptr &&		\
+			     ((plane) = (__state)->planes[__i].ptr,	\
+			      (old_plane_state) = (__state)->planes[__i].old_state, 1))
 /**
  * for_each_new_plane_in_state - iterate over all planes in an atomic update
  * @__state: &struct drm_atomic_state pointer
@@ -744,11 +743,11 @@ void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
  */
 #define for_each_new_plane_in_state(__state, plane, new_plane_state, __i) \
 	for ((__i) = 0;							\
-	     (__i) < (__state)->dev->mode_config.num_total_plane &&	\
-	     ((plane) = (__state)->planes[__i].ptr,			\
-	     (new_plane_state) = (__state)->planes[__i].new_state, 1);	\
+	     (__i) < (__state)->dev->mode_config.num_total_plane;	\
 	     (__i)++)							\
-		for_each_if (plane)
+		for_each_if ((__state)->planes[__i].ptr &&		\
+			     ((plane) = (__state)->planes[__i].ptr,	\
+			      (new_plane_state) = (__state)->planes[__i].new_state, 1))
 
 /**
  * for_each_oldnew_private_obj_in_state - iterate over all private objects in an atomic update