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Commit cbe12e74 authored by Thomas Hellstrom's avatar Thomas Hellstrom
Browse files

drm/ttm: Allow vm fault retries 



Make use of the FAULT_FLAG_ALLOW_RETRY flag to allow dropping the
mmap_sem while waiting for bo idle.

FAULT_FLAG_ALLOW_RETRY appears to be primarily designed for disk waits
but should work just as fine for GPU waits..

Signed-off-by: default avatarThomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: default avatarJakob Bornecrantz <jakob@vmware.com>
parent 4695b039

drivers/gpu/drm/ttm/ttm_bo_vm.c

+50 −12
Original line number Diff line number Diff line
@@ -41,6 +41,51 @@ 


#define TTM_BO_VM_NUM_PREFAULT 16



static int ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,

				struct vm_area_struct *vma,

				struct vm_fault *vmf)

{

	struct ttm_bo_device *bdev = bo->bdev;

	int ret = 0;



	spin_lock(&bdev->fence_lock);

	if (likely(!test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)))

		goto out_unlock;



	/*

	 * Quick non-stalling check for idle.

	 */

	ret = ttm_bo_wait(bo, false, false, true);

	if (likely(ret == 0))

		goto out_unlock;



	/*

	 * If possible, avoid waiting for GPU with mmap_sem

	 * held.

	 */

	if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {

		ret = VM_FAULT_RETRY;

		if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)

			goto out_unlock;



		up_read(&vma->vm_mm->mmap_sem);

		(void) ttm_bo_wait(bo, false, true, false);

		goto out_unlock;

	}



	/*

	 * Ordinary wait.

	 */

	ret = ttm_bo_wait(bo, false, true, false);

	if (unlikely(ret != 0))

		ret = (ret != -ERESTARTSYS) ? VM_FAULT_SIGBUS :

			VM_FAULT_NOPAGE;



out_unlock:

	spin_unlock(&bdev->fence_lock);

	return ret;

}



static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)

{

	struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
@@ -91,18 +136,11 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 
	 * Wait for buffer data in transit, due to a pipelined

	 * move.

	 */



	spin_lock(&bdev->fence_lock);

	if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {

		ret = ttm_bo_wait(bo, false, true, false);

		spin_unlock(&bdev->fence_lock);

	ret = ttm_bo_vm_fault_idle(bo, vma, vmf);

	if (unlikely(ret != 0)) {

			retval = (ret != -ERESTARTSYS) ?

			    VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;

		retval = ret;

		goto out_unlock;

	}

	} else

		spin_unlock(&bdev->fence_lock);



	ret = ttm_mem_io_lock(man, true);

	if (unlikely(ret != 0)) {