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

Stefano Garzarella
2026-01-29T08:42:18Z

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@redhat.com>
>Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>---
>
>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@redhat.com>

>
>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
>