[PATCH net-next V2 3/5] virtio-net: switch to use new ctx API for small buffer

[Jason Wang]

Use ctx API to store headroom for small buffers.
Following patches will retrieve this info and use it for XDP.

Signed-off-by: Jason Wang <jasow...@redhat.com>
---
 drivers/net/virtio_net.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8fae9a8..640f1de 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -410,7 +410,8 @@ static unsigned int virtnet_get_headroom(struct 
virtnet_info *vi)
 static struct sk_buff *receive_small(struct net_device *dev,
                                     struct virtnet_info *vi,
                                     struct receive_queue *rq,
-                                    void *buf, unsigned int len)
+                                    void *buf, void *ctx,
+                                    unsigned int len)
 {
        struct sk_buff *skb;
        struct bpf_prog *xdp_prog;
@@ -773,7 +774,7 @@ static int receive_buf(struct virtnet_info *vi, struct 
receive_queue *rq,
        else if (vi->big_packets)
                skb = receive_big(dev, vi, rq, buf, len);
        else
-               skb = receive_small(dev, vi, rq, buf, len);
+               skb = receive_small(dev, vi, rq, buf, ctx, len);
 
        if (unlikely(!skb))
                return 0;
@@ -806,12 +807,18 @@ static int receive_buf(struct virtnet_info *vi, struct 
receive_queue *rq,
        return 0;
 }
 
+/* Unlike mergeable buffers, all buffers are allocated to the
+ * same size, except for the headroom. For this reason we do
+ * not need to use  mergeable_len_to_ctx here - it is enough
+ * to store the headroom as the context ignoring the truesize.
+ */
 static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
                             gfp_t gfp)
 {
        struct page_frag *alloc_frag = &rq->alloc_frag;
        char *buf;
        unsigned int xdp_headroom = virtnet_get_headroom(vi);
+       void *ctx = (void *)(unsigned long)xdp_headroom;
        int len = vi->hdr_len + VIRTNET_RX_PAD + GOOD_PACKET_LEN + xdp_headroom;
        int err;
 
@@ -825,7 +832,7 @@ static int add_recvbuf_small(struct virtnet_info *vi, 
struct receive_queue *rq,
        alloc_frag->offset += len;
        sg_init_one(rq->sg, buf + VIRTNET_RX_PAD + xdp_headroom,
                    vi->hdr_len + GOOD_PACKET_LEN);
-       err = virtqueue_add_inbuf(rq->vq, rq->sg, 1, buf, gfp);
+       err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
        if (err < 0)
                put_page(virt_to_head_page(buf));
 
@@ -1034,7 +1041,7 @@ static int virtnet_receive(struct receive_queue *rq, int 
budget)
        void *buf;
        struct virtnet_stats *stats = this_cpu_ptr(vi->stats);
 
-       if (vi->mergeable_rx_bufs) {
+       if (!vi->big_packets || vi->mergeable_rx_bufs) {
                void *ctx;
 
                while (received < budget &&
@@ -2198,7 +2205,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
        names = kmalloc(total_vqs * sizeof(*names), GFP_KERNEL);
        if (!names)
                goto err_names;
-       if (vi->mergeable_rx_bufs) {
+       if (!vi->big_packets || vi->mergeable_rx_bufs) {
                ctx = kzalloc(total_vqs * sizeof(*ctx), GFP_KERNEL);
                if (!ctx)
                        goto err_ctx;
-- 
2.7.4