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    SubjectRe: [PATCH v4 3/5] vsock/virtio: fix locking in virtio_transport_inc_tx_pkt()
    On Wed, Jul 17, 2019 at 01:30:28PM +0200, Stefano Garzarella wrote:
    > fwd_cnt and last_fwd_cnt are protected by rx_lock, so we should use
    > the same spinlock also if we are in the TX path.
    >
    > Move also buf_alloc under the same lock.
    >
    > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

    Wait a second is this a bugfix?
    If it's used under the wrong lock won't values get corrupted?
    Won't traffic then stall or more data get to sent than
    credits?

    > ---
    > include/linux/virtio_vsock.h | 2 +-
    > net/vmw_vsock/virtio_transport_common.c | 4 ++--
    > 2 files changed, 3 insertions(+), 3 deletions(-)
    >
    > diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
    > index 49fc9d20bc43..4c7781f4b29b 100644
    > --- a/include/linux/virtio_vsock.h
    > +++ b/include/linux/virtio_vsock.h
    > @@ -35,7 +35,6 @@ struct virtio_vsock_sock {
    >
    > /* Protected by tx_lock */
    > u32 tx_cnt;
    > - u32 buf_alloc;
    > u32 peer_fwd_cnt;
    > u32 peer_buf_alloc;
    >
    > @@ -43,6 +42,7 @@ struct virtio_vsock_sock {
    > u32 fwd_cnt;
    > u32 last_fwd_cnt;
    > u32 rx_bytes;
    > + u32 buf_alloc;
    > struct list_head rx_queue;
    > };
    >
    > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
    > index a85559d4d974..34a2b42313b7 100644
    > --- a/net/vmw_vsock/virtio_transport_common.c
    > +++ b/net/vmw_vsock/virtio_transport_common.c
    > @@ -210,11 +210,11 @@ static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
    >
    > 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);
    > vvs->last_fwd_cnt = vvs->fwd_cnt;
    > 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);
    >
    > --
    > 2.20.1

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