On Tue, May 28, 2024 at 03:52:26PM +0800, Heng Qi wrote:
> Refactored the handling of control_buf to be within the cvq_lock
> critical section, mitigating race conditions between reading device
> responses and new command submissions.
>
> Fixes: 6f45ab3e0409 ("virtio_net: Add a lock for the command VQ.")
> Signed-off-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>
I don't get what does this change. status can change immediately
after you drop the mutex, can it not? what exactly is the
race conditions you are worried about?
> ---
> drivers/net/virtio_net.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 6b0512a628e0..3d8407d9e3d2 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2686,6 +2686,7 @@ static bool virtnet_send_command_reply(struct virtnet_info *vi, u8 class, u8 cmd
> {
> struct scatterlist *sgs[5], hdr, stat;
> u32 out_num = 0, tmp, in_num = 0;
> + bool ret;
> int err;
>
> /* Caller should know better */
> @@ -2731,8 +2732,9 @@ static bool virtnet_send_command_reply(struct virtnet_info *vi, u8 class, u8 cmd
> }
>
> unlock:
> + ret = vi->ctrl->status == VIRTIO_NET_OK;
> mutex_unlock(&vi->cvq_lock);
> - return vi->ctrl->status == VIRTIO_NET_OK;
> + return ret;
> }
>
> static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> --
> 2.32.0.3.g01195cf9f
