Re: [RFC PATCH v2 2/5] vhost/vsock: support MSG_EOR bit processing

[Stefano Garzarella]

On Tue, Aug 10, 2021 at 02:40:15PM +0300, Arseny Krasnov wrote:
> It works in the same way as 'end-of-message' bit: if packet has
> 'EOM' bit, also check for 'EOR' bit.

Please describe all changes, e.g. the new variable to accumulate flags 
to restore.

> Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
> ---
> drivers/vhost/vsock.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index feaf650affbe..06fc132b13c8 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -114,7 +114,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 		size_t nbytes;
> 		size_t iov_len, payload_len;
> 		int head;
> -		bool restore_flag = false;
> +		uint32_t flags_to_restore = 0;
>
> 		spin_lock_bh(&vsock->send_pkt_list_lock);
> 		if (list_empty(&vsock->send_pkt_list)) {
> @@ -187,7 +187,12 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 			 */
> 			if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) {
> 				pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
> -				restore_flag = true;
> +				flags_to_restore |= le32_to_cpu(VIRTIO_VSOCK_SEQ_EOM);
> +
> +				if (le32_to_cpu(pkt->hdr.flags & VIRTIO_VSOCK_SEQ_EOR)) {
> +					pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> +					flags_to_restore |= le32_to_cpu(VIRTIO_VSOCK_SEQ_EOR);
                                                            ^
I'm not sure this is needed, VIRTIO_VSOCK_SEQ_EOR is represented in the 
cpu endianess.

I think here you can simpy do `flags_to_restore |= VIRTIO_VSOCK_SEQ_EOR` 
then use `pkt->hdr.flags |= cpu_to_le32(flags_to_restore);` as you 
already do.

> +				}
> 			}
> 		}
>
> @@ -224,8 +229,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 		 * to send it with the next available buffer.
> 		 */
> 		if (pkt->off < pkt->len) {
> -			if (restore_flag)
> -				pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
> +			pkt->hdr.flags |= cpu_to_le32(flags_to_restore);
>
> 			/* We are queueing the same virtio_vsock_pkt to handle
> 			 * the remaining bytes, and we want to deliver it
> --
> 2.25.1