Re: [PATCH net-next v4 3/6] vhost/vsock: support MSG_EOR bit processing

[Stefano Garzarella]

On Fri, Sep 03, 2021 at 09:15:38AM +0300, Arseny Krasnov wrote:
> 'MSG_EOR' handling has similar logic as 'MSG_EOM' - if bit present
> in packet's header, reset it to 0. Then restore it back if packet
> processing wasn't completed. Instead of bool variable for each
> flag, bit mask variable was added: it has logical OR of 'MSG_EOR'
> and 'MSG_EOM' if needed, to restore flags, this variable is ORed
> with flags field of packet.
>
> Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
> ---
> drivers/vhost/vsock.c | 22 +++++++++++++---------
> 1 file changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index feaf650affbe..93e8d635e18f 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;
> +		u32 flags_to_restore = 0;
>
> 		spin_lock_bh(&vsock->send_pkt_list_lock);
> 		if (list_empty(&vsock->send_pkt_list)) {
> @@ -179,15 +179,20 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 			 * created dynamically and are initialized with header
> 			 * of current packet(except length). But in case of
> 			 * SOCK_SEQPACKET, we also must clear message delimeter
> -			 * bit(VIRTIO_VSOCK_SEQ_EOM). Otherwise, instead of one
> -			 * packet with delimeter(which marks end of message),
> -			 * there will be sequence of packets with delimeter
> -			 * bit set. After initialized header will be copied to
> -			 * rx buffer, this bit will be restored.
> +			 * bit (VIRTIO_VSOCK_SEQ_EOM) and MSG_EOR bit
> +			 * (VIRTIO_VSOCK_SEQ_EOR) if set. Otherwise,
> +			 * there will be sequence of packets with these
> +			 * bits set. After initialized header will be copied to
> +			 * rx buffer, these required bits will be restored.
> 			 */
> 			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 |= 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 |= VIRTIO_VSOCK_SEQ_EOR;
> +				}
> 			}
> 		}
>
> @@ -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

Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>