linux-kernel - Re: [PATCH v2 5/8] vsock/virtio: Add vsock helper for linear SKB allocation

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Message-ID: <vaq3g5wtt657w532itcpdwsvf742cglvuckiqcyueg7y72wtko@yg7swar2xnwh>
Date: Wed, 2 Jul 2025 18:40:17 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Will Deacon <will@...nel.org>
Cc: linux-kernel@...r.kernel.org, Keir Fraser <keirf@...gle.com>, 
	Steven Moreland <smoreland@...gle.com>, Frederick Mayle <fmayle@...gle.com>, 
	Stefan Hajnoczi <stefanha@...hat.com>, "Michael S. Tsirkin" <mst@...hat.com>, 
	Jason Wang <jasowang@...hat.com>, Eugenio Pérez <eperezma@...hat.com>, 
	netdev@...r.kernel.org, virtualization@...ts.linux.dev
Subject: Re: [PATCH v2 5/8] vsock/virtio: Add vsock helper for linear SKB
 allocation

On Tue, Jul 01, 2025 at 05:45:04PM +0100, Will Deacon wrote:
>In preparation for nonlinear allocations for large SKBs, introduce a
>new virtio_vsock_alloc_linear_skb() helper to return linear SKBs
>unconditionally and switch all callers over to this new interface for
>now.
>
>No functional change.
>
>Signed-off-by: Will Deacon <will@...nel.org>
>---
> drivers/vhost/vsock.c                   | 2 +-
> include/linux/virtio_vsock.h            | 6 ++++++
> net/vmw_vsock/virtio_transport.c        | 2 +-
> net/vmw_vsock/virtio_transport_common.c | 2 +-
> 4 files changed, 9 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index 66a0f060770e..b13f6be452ba 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -348,7 +348,7 @@ vhost_vsock_alloc_skb(struct vhost_virtqueue *vq,
> 		return NULL;
>
> 	/* len contains both payload and hdr */
>-	skb = virtio_vsock_alloc_skb(len, GFP_KERNEL);
>+	skb = virtio_vsock_alloc_linear_skb(len, GFP_KERNEL);
> 	if (!skb)
> 		return NULL;
>
>diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
>index 1b5731186095..6d4a933c895a 100644
>--- a/include/linux/virtio_vsock.h
>+++ b/include/linux/virtio_vsock.h
>@@ -70,6 +70,12 @@ static inline struct sk_buff *virtio_vsock_alloc_skb(unsigned int size, gfp_t ma
> 	return skb;
> }
>
>+static inline struct sk_buff *
>+virtio_vsock_alloc_linear_skb(unsigned int size, gfp_t mask)
>+{
>+	return virtio_vsock_alloc_skb(size, mask);

Why not just renaming virtio_vsock_alloc_skb in this patch?

In that way we are sure when building this patch we don't leave any 
"old" virtio_vsock_alloc_skb() around.

Thanks,
Stefano

>+}
>+
> static inline void
> virtio_vsock_skb_queue_head(struct sk_buff_head *list, struct sk_buff *skb)
> {
>diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>index 3daba06ed499..2959db0404ed 100644
>--- a/net/vmw_vsock/virtio_transport.c
>+++ b/net/vmw_vsock/virtio_transport.c
>@@ -321,7 +321,7 @@ static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
> 	vq = vsock->vqs[VSOCK_VQ_RX];
>
> 	do {
>-		skb = virtio_vsock_alloc_skb(total_len, GFP_KERNEL);
>+		skb = virtio_vsock_alloc_linear_skb(total_len, GFP_KERNEL);
> 		if (!skb)
> 			break;
>
>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>index 1b5d9896edae..c9eb7f7ac00d 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -261,7 +261,7 @@ static struct sk_buff *virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *
> 	if (!zcopy)
> 		skb_len += payload_len;
>
>-	skb = virtio_vsock_alloc_skb(skb_len, GFP_KERNEL);
>+	skb = virtio_vsock_alloc_linear_skb(skb_len, GFP_KERNEL);
> 	if (!skb)
> 		return NULL;
>
>-- 
>2.50.0.727.gbf7dc18ff4-goog
>