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drm/ttm: fix fence locking in ttm_buffer_object_transfer, 2nd try

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This fixes up

commit e8e89622ed
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Dec 18 22:25:11 2012 +0100

    drm/ttm: fix fence locking in ttm_buffer_object_transfer

which leaves behind a might_sleep in atomic context, since the
fence_lock spinlock is held over a kmalloc(GFP_KERNEL) call. The fix
is to revert the above commit and only take the lock where we need it,
around the call to ->sync_obj_ref.

v2: Fixup things noticed by Maarten Lankhorst:
- Brown paper bag locking bug.
- No need for kzalloc if we clear the entire thing on the next line.
- check for bo->sync_obj (totally unlikely race, but still someone
  else could have snuck in) and clear fbo->sync_obj if it's cleared
  already.

Reported-by: Dave Airlie <airlied@gmail.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Daniel Vetter 2013-01-14 15:08:14 +01:00 committed by Dave Airlie
parent 6bacaa9dda
commit ff7c60c580
1 changed files with 8 additions and 5 deletions
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13
drivers/gpu/drm/ttm/ttm_bo_util.c
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@ -429,7 +429,7 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
struct ttm_bo_device *bdev = bo->bdev;
struct ttm_bo_driver *driver = bdev->driver;
fbo = kzalloc(sizeof(*fbo), GFP_KERNEL);
fbo = kmalloc(sizeof(*fbo), GFP_KERNEL);
if (!fbo)
return -ENOMEM;
@ -448,7 +448,12 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
fbo->vm_node = NULL;
atomic_set(&fbo->cpu_writers, 0);
fbo->sync_obj = driver->sync_obj_ref(bo->sync_obj);
spin_lock(&bdev->fence_lock);
if (bo->sync_obj)
fbo->sync_obj = driver->sync_obj_ref(bo->sync_obj);
else
fbo->sync_obj = NULL;
spin_unlock(&bdev->fence_lock);
kref_init(&fbo->list_kref);
kref_init(&fbo->kref);
fbo->destroy = &ttm_transfered_destroy;
@ -661,13 +666,11 @@ int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
*/
set_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags);
/* ttm_buffer_object_transfer accesses bo->sync_obj */
ret = ttm_buffer_object_transfer(bo, &ghost_obj);
spin_unlock(&bdev->fence_lock);
if (tmp_obj)
driver->sync_obj_unref(&tmp_obj);
ret = ttm_buffer_object_transfer(bo, &ghost_obj);
if (ret)
return ret;