[RFC PATCH v2 2/7] Revert "virtio_net: xsk: rx: support recv small mode"

["Michael S. Tsirkin" <mst@redhat.com>]

This reverts commit a4e7ba7027012f009f22a68bcfde670f9298d3a4.

leads to crashes with no ACCESS_PLATFORM when
sysctl net.core.high_order_alloc_disable=1

Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Reported-by: Si-Wei Liu <si-wei.liu@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/net/virtio_net.c | 198 ++++-----------------------------------
 1 file changed, 19 insertions(+), 179 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 15e202dd6964..041c483a06c5 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -498,12 +498,6 @@ struct virtio_net_common_hdr {
 };
 
 static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);
-static int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
-			       struct net_device *dev,
-			       unsigned int *xdp_xmit,
-			       struct virtnet_rq_stats *stats);
-static void virtnet_receive_done(struct virtnet_info *vi, struct receive_queue *rq,
-				 struct sk_buff *skb, u8 flags);
 
 static bool is_xdp_frame(void *ptr)
 {
@@ -1068,124 +1062,6 @@ static void sg_fill_dma(struct scatterlist *sg, dma_addr_t addr, u32 len)
 	sg->length = len;
 }
 
-static struct xdp_buff *buf_to_xdp(struct virtnet_info *vi,
-				   struct receive_queue *rq, void *buf, u32 len)
-{
-	struct xdp_buff *xdp;
-	u32 bufsize;
-
-	xdp = (struct xdp_buff *)buf;
-
-	bufsize = xsk_pool_get_rx_frame_size(rq->xsk_pool) + vi->hdr_len;
-
-	if (unlikely(len > bufsize)) {
-		pr_debug("%s: rx error: len %u exceeds truesize %u\n",
-			 vi->dev->name, len, bufsize);
-		DEV_STATS_INC(vi->dev, rx_length_errors);
-		xsk_buff_free(xdp);
-		return NULL;
-	}
-
-	xsk_buff_set_size(xdp, len);
-	xsk_buff_dma_sync_for_cpu(xdp);
-
-	return xdp;
-}
-
-static struct sk_buff *xsk_construct_skb(struct receive_queue *rq,
-					 struct xdp_buff *xdp)
-{
-	unsigned int metasize = xdp->data - xdp->data_meta;
-	struct sk_buff *skb;
-	unsigned int size;
-
-	size = xdp->data_end - xdp->data_hard_start;
-	skb = napi_alloc_skb(&rq->napi, size);
-	if (unlikely(!skb)) {
-		xsk_buff_free(xdp);
-		return NULL;
-	}
-
-	skb_reserve(skb, xdp->data_meta - xdp->data_hard_start);
-
-	size = xdp->data_end - xdp->data_meta;
-	memcpy(__skb_put(skb, size), xdp->data_meta, size);
-
-	if (metasize) {
-		__skb_pull(skb, metasize);
-		skb_metadata_set(skb, metasize);
-	}
-
-	xsk_buff_free(xdp);
-
-	return skb;
-}
-
-static struct sk_buff *virtnet_receive_xsk_small(struct net_device *dev, struct virtnet_info *vi,
-						 struct receive_queue *rq, struct xdp_buff *xdp,
-						 unsigned int *xdp_xmit,
-						 struct virtnet_rq_stats *stats)
-{
-	struct bpf_prog *prog;
-	u32 ret;
-
-	ret = XDP_PASS;
-	rcu_read_lock();
-	prog = rcu_dereference(rq->xdp_prog);
-	if (prog)
-		ret = virtnet_xdp_handler(prog, xdp, dev, xdp_xmit, stats);
-	rcu_read_unlock();
-
-	switch (ret) {
-	case XDP_PASS:
-		return xsk_construct_skb(rq, xdp);
-
-	case XDP_TX:
-	case XDP_REDIRECT:
-		return NULL;
-
-	default:
-		/* drop packet */
-		xsk_buff_free(xdp);
-		u64_stats_inc(&stats->drops);
-		return NULL;
-	}
-}
-
-static void virtnet_receive_xsk_buf(struct virtnet_info *vi, struct receive_queue *rq,
-				    void *buf, u32 len,
-				    unsigned int *xdp_xmit,
-				    struct virtnet_rq_stats *stats)
-{
-	struct net_device *dev = vi->dev;
-	struct sk_buff *skb = NULL;
-	struct xdp_buff *xdp;
-	u8 flags;
-
-	len -= vi->hdr_len;
-
-	u64_stats_add(&stats->bytes, len);
-
-	xdp = buf_to_xdp(vi, rq, buf, len);
-	if (!xdp)
-		return;
-
-	if (unlikely(len < ETH_HLEN)) {
-		pr_debug("%s: short packet %i\n", dev->name, len);
-		DEV_STATS_INC(dev, rx_length_errors);
-		xsk_buff_free(xdp);
-		return;
-	}
-
-	flags = ((struct virtio_net_common_hdr *)(xdp->data - vi->hdr_len))->hdr.flags;
-
-	if (!vi->mergeable_rx_bufs)
-		skb = virtnet_receive_xsk_small(dev, vi, rq, xdp, xdp_xmit, stats);
-
-	if (skb)
-		virtnet_receive_done(vi, rq, skb, flags);
-}
-
 static int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct receive_queue *rq,
 				   struct xsk_buff_pool *pool, gfp_t gfp)
 {
@@ -2516,67 +2392,31 @@ static void refill_work(struct work_struct *work)
 	}
 }
 
-static int virtnet_receive_xsk_bufs(struct virtnet_info *vi,
-				    struct receive_queue *rq,
-				    int budget,
-				    unsigned int *xdp_xmit,
-				    struct virtnet_rq_stats *stats)
-{
-	unsigned int len;
-	int packets = 0;
-	void *buf;
-
-	while (packets < budget) {
-		buf = virtqueue_get_buf(rq->vq, &len);
-		if (!buf)
-			break;
-
-		virtnet_receive_xsk_buf(vi, rq, buf, len, xdp_xmit, stats);
-		packets++;
-	}
-
-	return packets;
-}
-
-static int virtnet_receive_packets(struct virtnet_info *vi,
-				   struct receive_queue *rq,
-				   int budget,
-				   unsigned int *xdp_xmit,
-				   struct virtnet_rq_stats *stats)
-{
-	unsigned int len;
-	int packets = 0;
-	void *buf;
-
-	if (!vi->big_packets || vi->mergeable_rx_bufs) {
-		void *ctx;
-		while (packets < budget &&
-		       (buf = virtnet_rq_get_buf(rq, &len, &ctx))) {
-			receive_buf(vi, rq, buf, len, ctx, xdp_xmit, stats);
-			packets++;
-		}
-	} else {
-		while (packets < budget &&
-		       (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) {
-			receive_buf(vi, rq, buf, len, NULL, xdp_xmit, stats);
-			packets++;
-		}
-	}
-
-	return packets;
-}
-
 static int virtnet_receive(struct receive_queue *rq, int budget,
 			   unsigned int *xdp_xmit)
 {
 	struct virtnet_info *vi = rq->vq->vdev->priv;
 	struct virtnet_rq_stats stats = {};
-	int i, packets;
+	unsigned int len;
+	int packets = 0;
+	void *buf;
+	int i;
 
-	if (rq->xsk_pool)
-		packets = virtnet_receive_xsk_bufs(vi, rq, budget, xdp_xmit, &stats);
-	else
-		packets = virtnet_receive_packets(vi, rq, budget, xdp_xmit, &stats);
+	if (!vi->big_packets || vi->mergeable_rx_bufs) {
+		void *ctx;
+
+		while (packets < budget &&
+		       (buf = virtnet_rq_get_buf(rq, &len, &ctx))) {
+			receive_buf(vi, rq, buf, len, ctx, xdp_xmit, &stats);
+			packets++;
+		}
+	} else {
+		while (packets < budget &&
+		       (buf = virtqueue_get_buf(rq->vq, &len)) != NULL) {
+			receive_buf(vi, rq, buf, len, NULL, xdp_xmit, &stats);
+			packets++;
+		}
+	}
 
 	if (rq->vq->num_free > min((unsigned int)budget, virtqueue_get_vring_size(rq->vq)) / 2) {
 		if (!try_fill_recv(vi, rq, GFP_ATOMIC)) {
-- 
MST