From: Breno Leitao leitao@debian.org

[ Upstream commit f8321fa75102246d7415a6af441872f6637c93ab ]

After the commit bdacf3e34945 ("net: Use nested-BH locking for napi_alloc_cache.") was merged, the following warning began to appear:

WARNING: CPU: 5 PID: 1 at net/core/skbuff.c:1451 napi_skb_cache_put+0x82/0x4b0

__warn+0x12f/0x340 napi_skb_cache_put+0x82/0x4b0 napi_skb_cache_put+0x82/0x4b0 report_bug+0x165/0x370 handle_bug+0x3d/0x80 exc_invalid_op+0x1a/0x50 asm_exc_invalid_op+0x1a/0x20 __free_old_xmit+0x1c8/0x510 napi_skb_cache_put+0x82/0x4b0 __free_old_xmit+0x1c8/0x510 __free_old_xmit+0x1c8/0x510 __pfx___free_old_xmit+0x10/0x10

The issue arises because virtio is assuming it's running in NAPI context even when it's not, such as in the netpoll case.

To resolve this, modify virtnet_poll_tx() to only set NAPI when budget is available. Same for virtnet_poll_cleantx(), which always assumed that it was in a NAPI context.

Fixes: df133f3f9625 ("virtio_net: bulk free tx skbs") Suggested-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Breno Leitao leitao@debian.org Reviewed-by: Jakub Kicinski kuba@kernel.org Acked-by: Michael S. Tsirkin mst@redhat.com Acked-by: Jason Wang jasowang@redhat.com Reviewed-by: Heng Qi hengqi@linux.alibaba.com Link: https://patch.msgid.link/20240712115325.54175-1-leitao@debian.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org [Shivani: Modified to apply on v6.1.y] Signed-off-by: Shivani Agarwal shivani.agarwal@broadcom.com --- drivers/net/virtio_net.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 61cc0ed1ddc1..e3e5107adaca 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1638,7 +1638,7 @@ static bool is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q) return false; }

-static void virtnet_poll_cleantx(struct receive_queue *rq) +static void virtnet_poll_cleantx(struct receive_queue *rq, int budget) { struct virtnet_info *vi = rq->vq->vdev->priv; unsigned int index = vq2rxq(rq->vq); @@ -1656,7 +1656,7 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)

do { virtqueue_disable_cb(sq->vq); - free_old_xmit_skbs(sq, true); + free_old_xmit_skbs(sq, !!budget); } while (unlikely(!virtqueue_enable_cb_delayed(sq->vq)));

if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) @@ -1675,7 +1675,7 @@ static int virtnet_poll(struct napi_struct *napi, int budget) unsigned int received; unsigned int xdp_xmit = 0;

- virtnet_poll_cleantx(rq); + virtnet_poll_cleantx(rq, budget);

received = virtnet_receive(rq, budget, &xdp_xmit);

@@ -1778,7 +1778,7 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget) txq = netdev_get_tx_queue(vi->dev, index); __netif_tx_lock(txq, raw_smp_processor_id()); virtqueue_disable_cb(sq->vq); - free_old_xmit_skbs(sq, true); + free_old_xmit_skbs(sq, !!budget);

if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) netif_tx_wake_queue(txq);