drm/vc4: Use drm_gem_object_unreference_unlocked

Since my last struct_mutex crusade someone escaped!

This already has the advantage that for the common case when someone
else holds a ref the unref won't even acquire dev->struct_mutex. And
I'm working on code to allow drivers to completely opt-out of any and
all dev->struct_mutex usage, but that only works if they use the
_unlocked variants everywhere.

v2: Drop comment too.

v3: Drop the other comment too.

Cc: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1464630800-30786-15-git-send-email-daniel.vetter@ffwll.ch

2 files changed, 3 insertions, 10 deletions

diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index e5a9d3aaf45f..59adcf8532dd 100644
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -291,8 +291,6 @@ static void vc4_bo_cache_free_old(struct drm_device *dev)
 
 /* Called on the last userspace/kernel unreference of the BO.  Returns
  * it to the BO cache if possible, otherwise frees it.
- *
- * Note that this is called with the struct_mutex held.
  */
 void vc4_free_object(struct drm_gem_object *gem_bo)
 {
diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
index 46899d6de675..6155e8aca1c6 100644
--- a/drivers/gpu/drm/vc4/vc4_gem.c
+++ b/drivers/gpu/drm/vc4/vc4_gem.c
@@ -53,10 +53,8 @@ vc4_free_hang_state(struct drm_device *dev, struct vc4_hang_state *state)
 {
         unsigned int i;
 
-        mutex_lock(&dev->struct_mutex);
         for (i = 0; i < state->user_state.bo_count; i++)
-                drm_gem_object_unreference(state->bo[i]);
-        mutex_unlock(&dev->struct_mutex);
+                drm_gem_object_unreference_unlocked(state->bo[i]);
 
         kfree(state);
 }
@@ -687,11 +685,9 @@ vc4_complete_exec(struct drm_device *dev, struct vc4_exec_info *exec)
         struct vc4_dev *vc4 = to_vc4_dev(dev);
         unsigned i;
 
-        /* Need the struct lock for drm_gem_object_unreference(). */
-        mutex_lock(&dev->struct_mutex);
         if (exec->bo) {
                 for (i = 0; i < exec->bo_count; i++)
-                        drm_gem_object_unreference(&exec->bo[i]->base);
+                        drm_gem_object_unreference_unlocked(&exec->bo[i]->base);
                 kfree(exec->bo);
         }
 
@@ -699,9 +695,8 @@ vc4_complete_exec(struct drm_device *dev, struct vc4_exec_info *exec)
                 struct vc4_bo *bo = list_first_entry(&exec->unref_list,
                                                      struct vc4_bo, unref_head);
                 list_del(&bo->unref_head);
-                drm_gem_object_unreference(&bo->base.base);
+                drm_gem_object_unreference_unlocked(&bo->base.base);
         }
-        mutex_unlock(&dev->struct_mutex);
 
         mutex_lock(&vc4->power_lock);
         if (--vc4->power_refcount == 0)