Re: [PATCH v3 15/15] vsock/virtio: reorder fields to reduce padding

[Stefano Garzarella]

On Wed, Jan 28, 2026 at 03:31:21PM -0500, Michael S. Tsirkin wrote:
> Reorder struct virtio_vsock fields to place the DMA buffer (event_list)
> last. This eliminates the padding from aligning the struct size on
> ARCH_DMA_MINALIGN.
>
> Suggested-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
>
> changes from v2:
> 	move event_lock and event_run too, to keep
> 	event things logically together, as suggested by
> 	Stefano Garzarella.

Thanks for that!

Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>

> Note: this is the only change in v3 and it's cosmetic, so I am
> not reposting the whole patchset.
>
>
> net/vmw_vsock/virtio_transport.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> index 999a0839726a..b333a7591b26 100644
> --- a/net/vmw_vsock/virtio_transport.c
> +++ b/net/vmw_vsock/virtio_transport.c
> @@ -55,15 +55,6 @@ struct virtio_vsock {
> 	int rx_buf_nr;
> 	int rx_buf_max_nr;
>
> -	/* The following fields are protected by event_lock.
> -	 * vqs[VSOCK_VQ_EVENT] must be accessed with event_lock held.
> -	 */
> -	struct mutex event_lock;
> -	bool event_run;
> -	__dma_from_device_group_begin();
> -	struct virtio_vsock_event event_list[8];
> -	__dma_from_device_group_end();
> -
> 	u32 guest_cid;
> 	bool seqpacket_allow;
>
> @@ -77,6 +68,15 @@ struct virtio_vsock {
> 	 */
> 	struct scatterlist *out_sgs[MAX_SKB_FRAGS + 1];
> 	struct scatterlist out_bufs[MAX_SKB_FRAGS + 1];
> +
> +	/* The following fields are protected by event_lock.
> +	 * vqs[VSOCK_VQ_EVENT] must be accessed with event_lock held.
> +	 */
> +	struct mutex event_lock;
> +	bool event_run;
> +	__dma_from_device_group_begin();
> +	struct virtio_vsock_event event_list[8];
> +	__dma_from_device_group_end();
> };
>
> static u32 virtio_transport_get_local_cid(void)
> --
> MST