From: "Michael S. Tsirkin" <mst@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Jakub Kicinski <kuba@kernel.org>,
Jason Wang <jasowang@redhat.com>, Wei Wang <weiwan@google.com>,
David Miller <davem@davemloft.net>,
netdev@vger.kernel.org, Willem de Bruijn <willemb@google.com>,
virtualization@lists.linux-foundation.org
Subject: [PATCH RFC v2 3/4] virtio_net: move tx vq operation under tx queue lock
Date: Tue, 13 Apr 2021 01:47:52 -0400 [thread overview]
Message-ID: <20210413054733.36363-4-mst@redhat.com> (raw)
In-Reply-To: <20210413054733.36363-1-mst@redhat.com>
It's unsafe to operate a vq from multiple threads.
Unfortunately this is exactly what we do when invoking
clean tx poll from rx napi.
As a fix move everything that deals with the vq to under tx lock.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/net/virtio_net.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 16d5abed582c..460ccdbb840e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1505,6 +1505,8 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget)
struct virtnet_info *vi = sq->vq->vdev->priv;
unsigned int index = vq2txq(sq->vq);
struct netdev_queue *txq;
+ int opaque;
+ bool done;
if (unlikely(is_xdp_raw_buffer_queue(vi, index))) {
/* We don't need to enable cb for XDP */
@@ -1514,10 +1516,28 @@ 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);
+
+ opaque = virtqueue_enable_cb_prepare(sq->vq);
+
+ done = napi_complete_done(napi, 0);
+
+ if (!done)
+ virtqueue_disable_cb(sq->vq);
+
__netif_tx_unlock(txq);
- virtqueue_napi_complete(napi, sq->vq, 0);
+ if (done) {
+ if (unlikely(virtqueue_poll(sq->vq, opaque))) {
+ if (napi_schedule_prep(napi)) {
+ __netif_tx_lock(txq, raw_smp_processor_id());
+ virtqueue_disable_cb(sq->vq);
+ __netif_tx_unlock(txq);
+ __napi_schedule(napi);
+ }
+ }
+ }
if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS)
netif_tx_wake_queue(txq);
--
MST
next prev parent reply other threads:[~2021-04-13 5:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-13 5:47 [PATCH RFC v2 0/4] virtio net: spurious interrupt related fixes Michael S. Tsirkin
2021-04-13 5:47 ` [PATCH RFC v2 1/4] virtio: fix up virtio_disable_cb Michael S. Tsirkin
2021-04-13 8:51 ` Jason Wang
2021-04-13 14:01 ` Willem de Bruijn
2021-04-13 19:53 ` Michael S. Tsirkin
2021-04-13 21:44 ` Willem de Bruijn
2021-04-13 22:11 ` Michael S. Tsirkin
2021-04-14 0:24 ` Willem de Bruijn
2021-04-13 5:47 ` [PATCH RFC v2 2/4] virtio_net: disable cb aggressively Michael S. Tsirkin
2021-04-13 8:53 ` Jason Wang
2021-04-13 14:08 ` Willem de Bruijn
2021-04-13 14:33 ` Michael S. Tsirkin
2021-04-13 5:47 ` Michael S. Tsirkin [this message]
2021-04-13 8:54 ` [PATCH RFC v2 3/4] virtio_net: move tx vq operation under tx queue lock Jason Wang
2021-04-13 14:02 ` Michael S. Tsirkin
2021-04-13 14:20 ` Willem de Bruijn
2021-04-13 19:38 ` Michael S. Tsirkin
2021-04-13 5:47 ` [PATCH RFC v2 4/4] virtio_net: move txq wakeups under tx q lock Michael S. Tsirkin
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