[PATCH 3/3] drm/ttm: remove ttm_bo_wait_unreserved

[Daniel Vetter]

With nouveau fixed all ttm-using drives have the correct nesting of
mmap_sem vs dma_resv, and we can just lock the buffer.

Assuming I didn't screw up anything with my audit of course.

Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Cc: Christian Koenig <christian.koenig at amd.com>
Cc: Huang Rui <ray.huang at amd.com>
Cc: Gerd Hoffmann <kraxel at redhat.com>
Cc: "VMware Graphics" <linux-graphics-maintainer at vmware.com>
Cc: Thomas Hellstrom <thellstrom at vmware.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c    | 34 ---------------------------------
 drivers/gpu/drm/ttm/ttm_bo_vm.c | 26 +------------------------
 include/drm/ttm/ttm_bo_api.h    |  1 -
 3 files changed, 1 insertion(+), 60 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 20ff56f27aa4..a952dd624b06 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1954,37 +1954,3 @@ void ttm_bo_swapout_all(struct ttm_bo_device *bdev)
 		;
 }
 EXPORT_SYMBOL(ttm_bo_swapout_all);
-
-/**
- * ttm_bo_wait_unreserved - interruptible wait for a buffer object to become
- * unreserved
- *
- * @bo: Pointer to buffer
- */
-int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo)
-{
-	int ret;
-
-	/*
-	 * In the absense of a wait_unlocked API,
-	 * Use the bo::wu_mutex to avoid triggering livelocks due to
-	 * concurrent use of this function. Note that this use of
-	 * bo::wu_mutex can go away if we change locking order to
-	 * mmap_sem -> bo::reserve.
-	 */
-	ret = mutex_lock_interruptible(&bo->wu_mutex);
-	if (unlikely(ret != 0))
-		return -ERESTARTSYS;
-	if (!dma_resv_is_locked(bo->base.resv))
-		goto out_unlock;
-	ret = dma_resv_lock_interruptible(bo->base.resv, NULL);
-	if (ret == -EINTR)
-		ret = -ERESTARTSYS;
-	if (unlikely(ret != 0))
-		goto out_unlock;
-	dma_resv_unlock(bo->base.resv);
-
-out_unlock:
-	mutex_unlock(&bo->wu_mutex);
-	return ret;
-}
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 76eedb963693..505e1787aeea 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -125,31 +125,7 @@ static vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
 		&bdev->man[bo->mem.mem_type];
 	struct vm_area_struct cvma;
 
-	/*
-	 * Work around locking order reversal in fault / nopfn
-	 * between mmap_sem and bo_reserve: Perform a trylock operation
-	 * for reserve, and if it fails, retry the fault after waiting
-	 * for the buffer to become unreserved.
-	 */
-	if (unlikely(!dma_resv_trylock(bo->base.resv))) {
-		if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {
-			if (!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
-				ttm_bo_get(bo);
-				up_read(&vmf->vma->vm_mm->mmap_sem);
-				(void) ttm_bo_wait_unreserved(bo);
-				ttm_bo_put(bo);
-			}
-
-			return VM_FAULT_RETRY;
-		}
-
-		/*
-		 * If we'd want to change locking order to
-		 * mmap_sem -> bo::reserve, we'd use a blocking reserve here
-		 * instead of retrying the fault...
-		 */
-		return VM_FAULT_NOPAGE;
-	}
+	dma_resv_lock(bo->base.resv, NULL);
 
 	/*
 	 * Refuse to fault imported pages. This should be handled
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 43c4929a2171..6b50e624e3e2 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -765,7 +765,6 @@ ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp,
 int ttm_bo_swapout(struct ttm_bo_global *glob,
 			struct ttm_operation_ctx *ctx);
 void ttm_bo_swapout_all(struct ttm_bo_device *bdev);
-int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo);
 
 /**
  * ttm_bo_uses_embedded_gem_object - check if the given bo uses the
-- 
2.23.0.rc1