[PATCH 14/27] drm/vc4: Use drm_gem_object_unreference_unlocked

[Daniel Vetter]

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 at anholt.net>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 drivers/gpu/drm/vc4/vc4_bo.c  |  2 --
 drivers/gpu/drm/vc4/vc4_gem.c | 11 +++--------
 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)
-- 
2.8.1