[PATCH net-next v8 03/14] vsock: add netns to vsock skb cb

[Bobby Eshleman <bobbyeshleman@gmail.com>]

From: Bobby Eshleman <bobbyeshleman@meta.com>

Add a net pointer and net_mode to the vsock skb and helpers for
getting/setting them. When skbs are received the transport needs a way
to tell the vsock layer and/or virtio common layer which namespace and
what namespace mode the packet belongs to. This will be used by those
upper layers for finding the correct socket object. This patch stashes
these fields in the skb control buffer.

This extends virtio_vsock_skb_cb to 24 bytes:

struct virtio_vsock_skb_cb {
	struct net *               net;                  /*     0     8 */
	enum vsock_net_mode        net_mode;        /*     8     4 */
	u32                        offset;               /*    12     4 */
	bool                       reply;                /*    16     1 */
	bool                       tap_delivered;        /*    17     1 */

	/* size: 24, cachelines: 1, members: 5 */
	/* padding: 6 */
	/* last cacheline: 24 bytes */
};

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
Changes in v7:
- rename `orig_net_mode` to `net_mode`
- update commit message with a more complete explanation of changes

Changes in v5:
- some diff context change due to rebase to current net-next
---
 include/linux/virtio_vsock.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 87cf4dcac78a..7f334a32133c 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -10,6 +10,8 @@
 #define VIRTIO_VSOCK_SKB_HEADROOM (sizeof(struct virtio_vsock_hdr))
 
 struct virtio_vsock_skb_cb {
+	struct net *net;
+	enum vsock_net_mode net_mode;
 	u32 offset;
 	bool reply;
 	bool tap_delivered;
@@ -130,6 +132,27 @@ static inline size_t virtio_vsock_skb_len(struct sk_buff *skb)
 	return (size_t)(skb_end_pointer(skb) - skb->head);
 }
 
+static inline struct net *virtio_vsock_skb_net(struct sk_buff *skb)
+{
+	return VIRTIO_VSOCK_SKB_CB(skb)->net;
+}
+
+static inline void virtio_vsock_skb_set_net(struct sk_buff *skb, struct net *net)
+{
+	VIRTIO_VSOCK_SKB_CB(skb)->net = net;
+}
+
+static inline enum vsock_net_mode virtio_vsock_skb_net_mode(struct sk_buff *skb)
+{
+	return VIRTIO_VSOCK_SKB_CB(skb)->net_mode;
+}
+
+static inline void virtio_vsock_skb_set_net_mode(struct sk_buff *skb,
+						      enum vsock_net_mode net_mode)
+{
+	VIRTIO_VSOCK_SKB_CB(skb)->net_mode = net_mode;
+}
+
 /* Dimension the RX SKB so that the entire thing fits exactly into
  * a single 4KiB page. This avoids wasting memory due to alloc_skb()
  * rounding up to the next page order and also means that we

-- 
2.47.3