So this is a typical case where a NO_WAIT can indeed become a WAIT because of the use of a reservation instead of a spinlock.

(See the remove_fence_lock discussion)

/Thomas

On 10/12/2012 05:06 PM, Maarten Lankhorst wrote:

Apart from some code inside ttm itself and nouveau_bo_vma_del, this is the only place where ttm_bo_wait is used without a reservation. Fix this so we can remove the fence_lock later on.

Signed-off-by: Maarten Lankhorst maarten.lankhorst@canonical.com

drivers/gpu/drm/nouveau/nouveau_gem.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c index 5e2f521..18342b0 100644 --- a/drivers/gpu/drm/nouveau/nouveau_gem.c +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c @@ -837,17 +837,31 @@ nouveau_gem_ioctl_cpu_prep(struct drm_device *dev, void *data, struct drm_gem_object *gem; struct nouveau_bo *nvbo; bool no_wait = !!(req->flags & NOUVEAU_GEM_CPU_PREP_NOWAIT);

• int ret = -EINVAL;

• int ret;

• struct nouveau_fence *fence = NULL;

  gem = drm_gem_object_lookup(dev, file_priv, req->handle); if (!gem) return -ENOENT; nvbo = nouveau_gem_object(gem);

• spin_lock(&nvbo->bo.bdev->fence_lock);
• ret = ttm_bo_wait(&nvbo->bo, true, true, no_wait);
• spin_unlock(&nvbo->bo.bdev->fence_lock);

• ret = ttm_bo_reserve(&nvbo->bo, true, false, false, 0);
• if (!ret) {

• spin_lock(&nvbo->bo.bdev->fence_lock);
  

• ret = ttm_bo_wait(&nvbo->bo, true, true, true);
  

• if (!no_wait && ret)
  

• 	fence = nouveau_fence_ref(nvbo->bo.sync_obj);
  

• spin_unlock(&nvbo->bo.bdev->fence_lock);
  

• ttm_bo_unreserve(&nvbo->bo);
  

• } drm_gem_object_unreference_unlocked(gem);
• if (fence) {

• ret = nouveau_fence_wait(fence, true, no_wait);
  

• nouveau_fence_unref(&fence);
  

• }
• return ret; }

---

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