From 373701b1fc7d7c0013ae4fffd8103615c150751e Mon Sep 17 00:00:00 2001 From: Jani Nikula Date: Tue, 24 Nov 2015 21:21:55 +0200 Subject: [PATCH] drm: fix potential dangling else problems in for_each_ macros We have serious dangling else bugs waiting to happen in our for_each_ style macros with ifs. Consider, for example, #define drm_for_each_plane_mask(plane, dev, plane_mask) \ list_for_each_entry((plane), &(dev)->mode_config.plane_list, head) \ if ((plane_mask) & (1 << drm_plane_index(plane))) If this is used in context: if (condition) drm_for_each_plane_mask(plane, dev, plane_mask); else foo(); foo() will be called for each plane *not* in plane_mask, if condition holds, and not at all if condition doesn't hold. Fix this by reversing the conditions in the macros, and adding an else branch for the "for each" block, so that other if/else blocks can't interfere. Provide a "for_each_if" helper macro to make it easier to get this right. Signed-off-by: Jani Nikula Link: http://patchwork.freedesktop.org/patch/msgid/1448392916-2281-1-git-send-email-jani.nikula@intel.com Signed-off-by: Daniel Vetter --- include/drm/drmP.h | 3 +++ include/drm/drm_atomic.h | 6 +++--- include/drm/drm_crtc.h | 4 ++-- 3 files changed, 8 insertions(+), 5 deletions(-) diff --git a/include/drm/drmP.h b/include/drm/drmP.h index 0b921ae06cd8..30d4a5a495e2 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -1111,4 +1111,7 @@ static __inline__ bool drm_can_sleep(void) return true; } +/* helper for handling conditionals in various for_each macros */ +#define for_each_if(condition) if (!(condition)) {} else + #endif diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h index 4b74c97d297a..d8576ac55693 100644 --- a/include/drm/drm_atomic.h +++ b/include/drm/drm_atomic.h @@ -149,7 +149,7 @@ int __must_check drm_atomic_async_commit(struct drm_atomic_state *state); ((connector) = (state)->connectors[__i], \ (connector_state) = (state)->connector_states[__i], 1); \ (__i)++) \ - if (connector) + for_each_if (connector) #define for_each_crtc_in_state(state, crtc, crtc_state, __i) \ for ((__i) = 0; \ @@ -157,7 +157,7 @@ int __must_check drm_atomic_async_commit(struct drm_atomic_state *state); ((crtc) = (state)->crtcs[__i], \ (crtc_state) = (state)->crtc_states[__i], 1); \ (__i)++) \ - if (crtc_state) + for_each_if (crtc_state) #define for_each_plane_in_state(state, plane, plane_state, __i) \ for ((__i) = 0; \ @@ -165,7 +165,7 @@ int __must_check drm_atomic_async_commit(struct drm_atomic_state *state); ((plane) = (state)->planes[__i], \ (plane_state) = (state)->plane_states[__i], 1); \ (__i)++) \ - if (plane_state) + for_each_if (plane_state) static inline bool drm_atomic_crtc_needs_modeset(struct drm_crtc_state *state) { diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 173535a35d65..4765df331002 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -1170,7 +1170,7 @@ struct drm_mode_config { */ #define drm_for_each_plane_mask(plane, dev, plane_mask) \ list_for_each_entry((plane), &(dev)->mode_config.plane_list, head) \ - if ((plane_mask) & (1 << drm_plane_index(plane))) + for_each_if ((plane_mask) & (1 << drm_plane_index(plane))) #define obj_to_crtc(x) container_of(x, struct drm_crtc, base) @@ -1547,7 +1547,7 @@ static inline struct drm_property *drm_property_find(struct drm_device *dev, /* Plane list iterator for legacy (overlay only) planes. */ #define drm_for_each_legacy_plane(plane, dev) \ list_for_each_entry(plane, &(dev)->mode_config.plane_list, head) \ - if (plane->type == DRM_PLANE_TYPE_OVERLAY) + for_each_if (plane->type == DRM_PLANE_TYPE_OVERLAY) #define drm_for_each_plane(plane, dev) \ list_for_each_entry(plane, &(dev)->mode_config.plane_list, head) -- 2.20.1