4.20-stable review patch. If anyone has any objections, please let me know.
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From: Toshiaki Makita makita.toshiaki@lab.ntt.co.jp
[ Upstream commit 5050471d35d1316ba32dfcbb409978337eb9e75e
I had to fold commit df133f3f9625 ("virtio_net: bulk free tx skbs") into this to make it work. ]
We do not reset or free up unused buffers when enabling/disabling XDP, so it can happen that xdp_frames are freed after disabling XDP or sk_buffs are freed after enabling XDP on xdp tx queues. Thus we need to handle both forms (xdp_frames and sk_buffs) regardless of XDP setting. One way to trigger this problem is to disable XDP when napi_tx is enabled. In that case, virtnet_xdp_set() calls virtnet_napi_enable() which kicks NAPI. The NAPI handler will call virtnet_poll_cleantx() which invokes free_old_xmit_skbs() for queues which have been used by XDP.
Note that even with this change we need to keep skipping free_old_xmit_skbs() from NAPI handlers when XDP is enabled, because XDP tx queues do not aquire queue locks.
- v2: Use napi_consume_skb() instead of dev_consume_skb_any()
Fixes: 4941d472bf95 ("virtio-net: do not reset during XDP set") Signed-off-by: Toshiaki Makita makita.toshiaki@lab.ntt.co.jp Acked-by: Jason Wang jasowang@redhat.com Acked-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/virtio_net.c | 64 ++++++++++++++++++++++++++++++++++------------- 1 file changed, 47 insertions(+), 17 deletions(-)
--- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -57,6 +57,8 @@ module_param(napi_tx, bool, 0644); #define VIRTIO_XDP_TX BIT(0) #define VIRTIO_XDP_REDIR BIT(1)
+#define VIRTIO_XDP_FLAG BIT(0) + /* RX packet size EWMA. The average packet size is used to determine the packet * buffer size when refilling RX rings. As the entire RX ring may be refilled * at once, the weight is chosen so that the EWMA will be insensitive to short- @@ -251,6 +253,21 @@ struct padded_vnet_hdr { char padding[4]; };
+static bool is_xdp_frame(void *ptr) +{ + return (unsigned long)ptr & VIRTIO_XDP_FLAG; +} + +static void *xdp_to_ptr(struct xdp_frame *ptr) +{ + return (void *)((unsigned long)ptr | VIRTIO_XDP_FLAG); +} + +static struct xdp_frame *ptr_to_xdp(void *ptr) +{ + return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG); +} + /* Converting between virtqueue no. and kernel tx/rx queue no. * 0:rx0 1:tx0 2:rx1 3:tx1 ... 2N:rxN 2N+1:txN 2N+2:cvq */ @@ -461,7 +478,8 @@ static int __virtnet_xdp_xmit_one(struct
sg_init_one(sq->sg, xdpf->data, xdpf->len);
- err = virtqueue_add_outbuf(sq->vq, sq->sg, 1, xdpf, GFP_ATOMIC); + err = virtqueue_add_outbuf(sq->vq, sq->sg, 1, xdp_to_ptr(xdpf), + GFP_ATOMIC); if (unlikely(err)) return -ENOSPC; /* Caller handle free/refcnt */
@@ -481,13 +499,13 @@ static int virtnet_xdp_xmit(struct net_d { struct virtnet_info *vi = netdev_priv(dev); struct receive_queue *rq = vi->rq; - struct xdp_frame *xdpf_sent; struct bpf_prog *xdp_prog; struct send_queue *sq; unsigned int len; int drops = 0; int kicks = 0; int ret, err; + void *ptr; int i;
/* Only allow ndo_xdp_xmit if XDP is loaded on dev, as this @@ -506,8 +524,12 @@ static int virtnet_xdp_xmit(struct net_d }
/* Free up any pending old buffers before queueing new ones. */ - while ((xdpf_sent = virtqueue_get_buf(sq->vq, &len)) != NULL) - xdp_return_frame(xdpf_sent); + while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) { + if (likely(is_xdp_frame(ptr))) + xdp_return_frame(ptr_to_xdp(ptr)); + else + napi_consume_skb(ptr, false); + }
for (i = 0; i < n; i++) { struct xdp_frame *xdpf = frames[i]; @@ -1326,20 +1348,28 @@ static int virtnet_receive(struct receiv return stats.packets; }
-static void free_old_xmit_skbs(struct send_queue *sq) +static void free_old_xmit_skbs(struct send_queue *sq, bool in_napi) { - struct sk_buff *skb; unsigned int len; unsigned int packets = 0; unsigned int bytes = 0; + void *ptr;
- while ((skb = virtqueue_get_buf(sq->vq, &len)) != NULL) { - pr_debug("Sent skb %p\n", skb); + while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) { + if (likely(!is_xdp_frame(ptr))) { + struct sk_buff *skb = ptr;
- bytes += skb->len; - packets++; + pr_debug("Sent skb %p\n", skb);
- dev_consume_skb_any(skb); + bytes += skb->len; + napi_consume_skb(skb, in_napi); + } else { + struct xdp_frame *frame = ptr_to_xdp(ptr); + + bytes += frame->len; + xdp_return_frame(frame); + } + packets++; }
/* Avoid overhead when no packets have been processed @@ -1375,7 +1405,7 @@ static void virtnet_poll_cleantx(struct return;
if (__netif_tx_trylock(txq)) { - free_old_xmit_skbs(sq); + free_old_xmit_skbs(sq, true); __netif_tx_unlock(txq); }
@@ -1459,7 +1489,7 @@ static int virtnet_poll_tx(struct napi_s
txq = netdev_get_tx_queue(vi->dev, index); __netif_tx_lock(txq, raw_smp_processor_id()); - free_old_xmit_skbs(sq); + free_old_xmit_skbs(sq, true); __netif_tx_unlock(txq);
virtqueue_napi_complete(napi, sq->vq, 0); @@ -1528,7 +1558,7 @@ static netdev_tx_t start_xmit(struct sk_ bool use_napi = sq->napi.weight;
/* Free up any pending old buffers before queueing new ones. */ - free_old_xmit_skbs(sq); + free_old_xmit_skbs(sq, false);
if (use_napi && kick) virtqueue_enable_cb_delayed(sq->vq); @@ -1571,7 +1601,7 @@ static netdev_tx_t start_xmit(struct sk_ if (!use_napi && unlikely(!virtqueue_enable_cb_delayed(sq->vq))) { /* More just got used, free them then recheck. */ - free_old_xmit_skbs(sq); + free_old_xmit_skbs(sq, false); if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) { netif_start_subqueue(dev, qnum); virtqueue_disable_cb(sq->vq); @@ -2639,10 +2669,10 @@ static void free_unused_bufs(struct virt for (i = 0; i < vi->max_queue_pairs; i++) { struct virtqueue *vq = vi->sq[i].vq; while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) { - if (!is_xdp_raw_buffer_queue(vi, i)) + if (!is_xdp_frame(buf)) dev_kfree_skb(buf); else - xdp_return_frame(buf); + xdp_return_frame(ptr_to_xdp(buf)); } }