drm/qxl: Move main reference counter to GEM object instead of TTM ones

qxl_bo structure has two reference counters, one in the GEM object and
another in the TTM object. The GEM object keep a counter to the TTM object
so when GEM counter reached zero the TTM counter (using qxl_bo_unref) was
decremented. The qxl object is fully freed (both GEM and TTM part are cleaned)
when the TTM counter reach zero.
One issue was that surface idr structure has no owning on qxl_bo objects however
it contains a pointer to qxl_bo object. This caused some nasty race condition
for instance qxl_bo object was reaped even after counter was already zero.
This patch fix these races moving main counter (the one used by qxl_bo_(un)ref)
to GEM object which cleanup routine (qxl_gem_object_free) remove the idr pointer
(using qxl_surface_evict) when the counters are still valid.

Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/qxl/qxl_gem.c b/drivers/gpu/drm/qxl/qxl_gem.c
index b96f0c9d89b2d717b552d59c19e26d4828214f66..d9746e904ef13c4f2805185010aacf7ca5feb222 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_gem.c
+++ b/drivers/gpu/drm/qxl/qxl_gem.c
@@ -31,9 +31,15 @@
 void qxl_gem_object_free(struct drm_gem_object *gobj)
 {
        struct qxl_bo *qobj = gem_to_qxl_bo(gobj);
+       struct qxl_device *qdev;
+       struct ttm_buffer_object *tbo;
 
-       if (qobj)
-               qxl_bo_unref(&qobj);
+       qdev = (struct qxl_device *)gobj->dev->dev_private;
+
+       qxl_surface_evict(qdev, qobj, false);
+
+       tbo = &qobj->tbo;
+       ttm_bo_unref(&tbo);
 }
 
 int qxl_gem_object_create(struct qxl_device *qdev, int size,

diff --git a/drivers/gpu/drm/qxl/qxl_object.c b/drivers/gpu/drm/qxl/qxl_object.c
index cdeaf08fdc745a9b27600e78edc200e97e53c620..6d6f33de48f48a93da1a0eadf681c5ac46874b4a 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_object.c
+++ b/drivers/gpu/drm/qxl/qxl_object.c
@@ -208,19 +208,16 @@ void qxl_bo_kunmap_atomic_page(struct qxl_device *qdev,
 
 void qxl_bo_unref(struct qxl_bo **bo)
 {
-       struct ttm_buffer_object *tbo;
-
        if ((*bo) == NULL)
                return;
-       tbo = &((*bo)->tbo);
-       ttm_bo_unref(&tbo);
-       if (tbo == NULL)
-               *bo = NULL;
+
+       drm_gem_object_unreference_unlocked(&(*bo)->gem_base);
+       *bo = NULL;
 }
 
 struct qxl_bo *qxl_bo_ref(struct qxl_bo *bo)
 {
-       ttm_bo_reference(&bo->tbo);
+       drm_gem_object_reference(&bo->gem_base);
        return bo;
 }