[PATCH net-next v3 5/6] virtio_net: Add a lock for per queue RX coalesce

[Daniel Jurgens]

Once the RTNL locking around the control buffer is removed there can be
contention on the per queue RX interrupt coalescing data. Use a spin
lock per queue.

Signed-off-by: Daniel Jurgens <dani...@nvidia.com>
---
 drivers/net/virtio_net.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index b3aa4d2a15e9..8724caa7c2ed 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -190,6 +190,7 @@ struct receive_queue {
        u32 packets_in_napi;
 
        struct virtnet_interrupt_coalesce intr_coal;
+       spinlock_t intr_coal_lock;
 
        /* Chain pages by the private ptr. */
        struct page *pages;
@@ -3087,11 +3088,13 @@ static int virtnet_set_ringparam(struct net_device *dev,
                                return err;
 
                        /* The reason is same as the transmit virtqueue reset */
-                       err = virtnet_send_rx_ctrl_coal_vq_cmd(vi, i,
-                                                              
vi->intr_coal_rx.max_usecs,
-                                                              
vi->intr_coal_rx.max_packets);
-                       if (err)
-                               return err;
+                       scoped_guard(spinlock, &vi->rq[i].intr_coal_lock) {
+                               err = virtnet_send_rx_ctrl_coal_vq_cmd(vi, i,
+                                                                      
vi->intr_coal_rx.max_usecs,
+                                                                      
vi->intr_coal_rx.max_packets);
+                               if (err)
+                                       return err;
+                       }
                }
        }
 
@@ -3510,8 +3513,10 @@ static int virtnet_send_rx_notf_coal_cmds(struct 
virtnet_info *vi,
        vi->intr_coal_rx.max_usecs = ec->rx_coalesce_usecs;
        vi->intr_coal_rx.max_packets = ec->rx_max_coalesced_frames;
        for (i = 0; i < vi->max_queue_pairs; i++) {
-               vi->rq[i].intr_coal.max_usecs = ec->rx_coalesce_usecs;
-               vi->rq[i].intr_coal.max_packets = ec->rx_max_coalesced_frames;
+               scoped_guard(spinlock, &vi->rq[i].intr_coal_lock) {
+                       vi->rq[i].intr_coal.max_usecs = ec->rx_coalesce_usecs;
+                       vi->rq[i].intr_coal.max_packets = 
ec->rx_max_coalesced_frames;
+               }
        }
 
        return 0;
@@ -3542,6 +3547,7 @@ static int virtnet_send_rx_notf_coal_vq_cmds(struct 
virtnet_info *vi,
        u32 max_usecs, max_packets;
        int err;
 
+       guard(spinlock)(&vi->rq[queue].intr_coal_lock);
        max_usecs = vi->rq[queue].intr_coal.max_usecs;
        max_packets = vi->rq[queue].intr_coal.max_packets;
 
@@ -3606,6 +3612,7 @@ static void virtnet_rx_dim_work(struct work_struct *work)
        if (!rq->dim_enabled)
                goto out;
 
+       guard(spinlock)(&rq->intr_coal_lock);
        update_moder = net_dim_get_rx_moderation(dim->mode, dim->profile_ix);
        if (update_moder.usec != rq->intr_coal.max_usecs ||
            update_moder.pkts != rq->intr_coal.max_packets) {
@@ -3756,6 +3763,7 @@ static int virtnet_get_per_queue_coalesce(struct 
net_device *dev,
                return -EINVAL;
 
        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
+               guard(spinlock)(&vi->rq[queue].intr_coal_lock);
                ec->rx_coalesce_usecs = vi->rq[queue].intr_coal.max_usecs;
                ec->tx_coalesce_usecs = vi->sq[queue].intr_coal.max_usecs;
                ec->tx_max_coalesced_frames = 
vi->sq[queue].intr_coal.max_packets;
@@ -4501,6 +4509,7 @@ static int virtnet_alloc_queues(struct virtnet_info *vi)
 
                u64_stats_init(&vi->rq[i].stats.syncp);
                u64_stats_init(&vi->sq[i].stats.syncp);
+               spin_lock_init(&vi->rq[i].intr_coal_lock);
        }
 
        return 0;
-- 
2.42.0