drm/i915: Prevent concurrent tiling/framebuffer modifications
Reintroduce a lock around tiling vs framebuffer creation to prevent
modification of the obj->tiling_and_stride whilst the framebuffer is
being created. Rather than use struct_mutex once again, use the
per-object lock - this will also be required in future to prevent
changing the tiling whilst submitting rendering.
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Fixes: 24dbf51a55 ("drm/i915: struct_mutex is not required for allocating the framebuffer")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170301154128.2841-2-chris@chris-wilson.co.uk
			
			
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				| @ -165,7 +165,7 @@ struct drm_i915_gem_object { | ||||
| 	struct reservation_object *resv; | ||||
| 
 | ||||
| 	/** References from framebuffers, locks out tiling changes. */ | ||||
| 	atomic_t framebuffer_references; | ||||
| 	unsigned int framebuffer_references; | ||||
| 
 | ||||
| 	/** Record of address bit 17 of each page at last unbind. */ | ||||
| 	unsigned long *bit_17; | ||||
| @ -260,6 +260,16 @@ extern void drm_gem_object_unreference(struct drm_gem_object *); | ||||
| __deprecated | ||||
| extern void drm_gem_object_unreference_unlocked(struct drm_gem_object *); | ||||
| 
 | ||||
| static inline void i915_gem_object_lock(struct drm_i915_gem_object *obj) | ||||
| { | ||||
| 	reservation_object_lock(obj->resv, NULL); | ||||
| } | ||||
| 
 | ||||
| static inline void i915_gem_object_unlock(struct drm_i915_gem_object *obj) | ||||
| { | ||||
| 	reservation_object_unlock(obj->resv); | ||||
| } | ||||
| 
 | ||||
| static inline bool | ||||
| i915_gem_object_is_dead(const struct drm_i915_gem_object *obj) | ||||
| { | ||||
| @ -306,6 +316,12 @@ i915_gem_object_clear_active_reference(struct drm_i915_gem_object *obj) | ||||
| 
 | ||||
| void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj); | ||||
| 
 | ||||
| static inline bool | ||||
| i915_gem_object_is_framebuffer(const struct drm_i915_gem_object *obj) | ||||
| { | ||||
| 	return READ_ONCE(obj->framebuffer_references); | ||||
| } | ||||
| 
 | ||||
| static inline unsigned int | ||||
| i915_gem_object_get_tiling(struct drm_i915_gem_object *obj) | ||||
| { | ||||
|  | ||||
| @ -207,7 +207,7 @@ i915_gem_shrink(struct drm_i915_private *dev_priv, | ||||
| 
 | ||||
| 			if (!(flags & I915_SHRINK_ACTIVE) && | ||||
| 			    (i915_gem_object_is_active(obj) || | ||||
| 			     atomic_read(&obj->framebuffer_references))) | ||||
| 			     i915_gem_object_is_framebuffer(obj))) | ||||
| 				continue; | ||||
| 
 | ||||
| 			if (!can_release_pages(obj)) | ||||
|  | ||||
| @ -238,7 +238,7 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj, | ||||
| 	if ((tiling | stride) == obj->tiling_and_stride) | ||||
| 		return 0; | ||||
| 
 | ||||
| 	if (atomic_read(&obj->framebuffer_references)) | ||||
| 	if (i915_gem_object_is_framebuffer(obj)) | ||||
| 		return -EBUSY; | ||||
| 
 | ||||
| 	/* We need to rebind the object if its current allocation
 | ||||
| @ -258,6 +258,12 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj, | ||||
| 	if (err) | ||||
| 		return err; | ||||
| 
 | ||||
| 	i915_gem_object_lock(obj); | ||||
| 	if (i915_gem_object_is_framebuffer(obj)) { | ||||
| 		i915_gem_object_unlock(obj); | ||||
| 		return -EBUSY; | ||||
| 	} | ||||
| 
 | ||||
| 	/* If the memory has unknown (i.e. varying) swizzling, we pin the
 | ||||
| 	 * pages to prevent them being swapped out and causing corruption | ||||
| 	 * due to the change in swizzling. | ||||
| @ -294,6 +300,7 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj, | ||||
| 	} | ||||
| 
 | ||||
| 	obj->tiling_and_stride = tiling | stride; | ||||
| 	i915_gem_object_unlock(obj); | ||||
| 
 | ||||
| 	/* Force the fence to be reacquired for GTT access */ | ||||
| 	i915_gem_release_mmap(obj); | ||||
|  | ||||
| @ -14185,7 +14185,10 @@ static void intel_user_framebuffer_destroy(struct drm_framebuffer *fb) | ||||
| 
 | ||||
| 	drm_framebuffer_cleanup(fb); | ||||
| 
 | ||||
| 	WARN_ON(atomic_dec_return(&intel_fb->obj->framebuffer_references) < 0); | ||||
| 	i915_gem_object_lock(intel_fb->obj); | ||||
| 	WARN_ON(!intel_fb->obj->framebuffer_references--); | ||||
| 	i915_gem_object_unlock(intel_fb->obj); | ||||
| 
 | ||||
| 	i915_gem_object_put(intel_fb->obj); | ||||
| 
 | ||||
| 	kfree(intel_fb); | ||||
| @ -14262,12 +14265,16 @@ static int intel_framebuffer_init(struct intel_framebuffer *intel_fb, | ||||
| 				  struct drm_mode_fb_cmd2 *mode_cmd) | ||||
| { | ||||
| 	struct drm_i915_private *dev_priv = to_i915(obj->base.dev); | ||||
| 	unsigned int tiling = i915_gem_object_get_tiling(obj); | ||||
| 	u32 pitch_limit, stride_alignment; | ||||
| 	struct drm_format_name_buf format_name; | ||||
| 	u32 pitch_limit, stride_alignment; | ||||
| 	unsigned int tiling, stride; | ||||
| 	int ret = -EINVAL; | ||||
| 
 | ||||
| 	atomic_inc(&obj->framebuffer_references); | ||||
| 	i915_gem_object_lock(obj); | ||||
| 	obj->framebuffer_references++; | ||||
| 	tiling = i915_gem_object_get_tiling(obj); | ||||
| 	stride = i915_gem_object_get_stride(obj); | ||||
| 	i915_gem_object_unlock(obj); | ||||
| 
 | ||||
| 	if (mode_cmd->flags & DRM_MODE_FB_MODIFIERS) { | ||||
| 		/*
 | ||||
| @ -14339,11 +14346,9 @@ static int intel_framebuffer_init(struct intel_framebuffer *intel_fb, | ||||
| 	 * If there's a fence, enforce that | ||||
| 	 * the fb pitch and fence stride match. | ||||
| 	 */ | ||||
| 	if (tiling != I915_TILING_NONE && | ||||
| 	    mode_cmd->pitches[0] != i915_gem_object_get_stride(obj)) { | ||||
| 	if (tiling != I915_TILING_NONE && mode_cmd->pitches[0] !=  stride) { | ||||
| 		DRM_DEBUG("pitch (%d) must match tiling stride (%d)\n", | ||||
| 			  mode_cmd->pitches[0], | ||||
| 			  i915_gem_object_get_stride(obj)); | ||||
| 			  mode_cmd->pitches[0], stride); | ||||
| 		goto err; | ||||
| 	} | ||||
| 
 | ||||
| @ -14424,7 +14429,9 @@ static int intel_framebuffer_init(struct intel_framebuffer *intel_fb, | ||||
| 	return 0; | ||||
| 
 | ||||
| err: | ||||
| 	atomic_dec(&obj->framebuffer_references); | ||||
| 	i915_gem_object_lock(obj); | ||||
| 	obj->framebuffer_references--; | ||||
| 	i915_gem_object_unlock(obj); | ||||
| 	return ret; | ||||
| } | ||||
| 
 | ||||
|  | ||||
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