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Commit 2f18c2d1 authored by Tiwei Bie's avatar Tiwei Bie Committed by David S. Miller
Browse files

virtio_ring: introduce helper for indirect feature 



Introduce a helper to check whether we will use indirect
feature. It will be used by packed ring too.

Signed-off-by: default avatarTiwei Bie <tiwei.bie@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4d6a105e

drivers/virtio/virtio_ring.c

+13 −3
Original line number Diff line number Diff line
@@ -145,6 +145,18 @@ struct vring_virtqueue { 


#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)



static inline bool virtqueue_use_indirect(struct virtqueue *_vq,

					  unsigned int total_sg)

{

	struct vring_virtqueue *vq = to_vvq(_vq);



	/*

	 * If the host supports indirect descriptor tables, and we have multiple

	 * buffers, then go indirect. FIXME: tune this threshold

	 */

	return (vq->indirect && total_sg > 1 && vq->vq.num_free);

}



/*

 * Modern virtio devices have feature bits to specify whether they need a

 * quirk and bypass the IOMMU. If not there, just use the DMA API.
@@ -324,9 +336,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, 


	head = vq->free_head;



	/* If the host supports indirect descriptor tables, and we have multiple

	 * buffers, then go indirect. FIXME: tune this threshold */

	if (vq->indirect && total_sg > 1 && vq->vq.num_free)

	if (virtqueue_use_indirect(_vq, total_sg))

		desc = alloc_indirect_split(_vq, total_sg, gfp);

	else {

		desc = NULL;