[PATCH v2 3/8] vsock/virtio: fix locking for fwd_cnt and buf_alloc

Stefano Garzarella
2019-05-10T13:00:04Z

fwd_cnt is written with rx_lock, so we should read it using
the same spinlock also if we are in the TX path.

Move also buf_alloc under rx_lock and add a missing locking
when we modify it.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
include/linux/virtio_vsock.h | 2 +-
net/vmw_vsock/virtio_transport_common.c | 6 ++++--
2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 345f04ee9193..fb5954fc85c8 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -35,11 +35,11 @@ struct virtio_vsock_sock {

/* Protected by tx_lock */
u32 tx_cnt;
- u32 buf_alloc;
u32 peer_fwd_cnt;
u32 peer_buf_alloc;

/* Protected by rx_lock */
+ u32 buf_alloc;
u32 fwd_cnt;
u32 rx_bytes;
struct list_head rx_queue;
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 65c8b4a23f2b..f2e4e128bc86 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -246,10 +246,10 @@ static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs, u32 len)

void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt)
{
- spin_lock_bh(&vvs->tx_lock);
+ spin_lock_bh(&vvs->rx_lock);
pkt->hdr.fwd_cnt = cpu_to_le32(vvs->fwd_cnt);
pkt->hdr.buf_alloc = cpu_to_le32(vvs->buf_alloc);
- spin_unlock_bh(&vvs->tx_lock);
+ spin_unlock_bh(&vvs->rx_lock);
}
EXPORT_SYMBOL_GPL(virtio_transport_inc_tx_pkt);

@@ -469,7 +469,9 @@ void virtio_transport_set_buffer_size(struct vsock_sock *vsk, u64 val)
if (val > vvs->buf_size_max)
vvs->buf_size_max = val;
vvs->buf_size = val;
+ spin_lock_bh(&vvs->rx_lock);
vvs->buf_alloc = val;
+ spin_unlock_bh(&vvs->rx_lock);
}
EXPORT_SYMBOL_GPL(virtio_transport_set_buffer_size);

--
2.20.1