[PATCH net-next v5 8/9] net: check for driver support in netmem TX

[Mina Almasry <almasrymina@google.com>]

We should not enable netmem TX for drivers that don't declare support.

Check for driver netmem TX support during devmem TX binding and fail if
the driver does not have the functionality.

Check for driver support in validate_xmit_skb as well.

Signed-off-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>

---

v4:
- New patch

---
 net/core/dev.c         | 3 +++
 net/core/netdev-genl.c | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index 8c7ee7ada6a3..ba83b18fa703 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3921,6 +3921,9 @@ static struct sk_buff *validate_xmit_skb(struct sk_buff *skb, struct net_device
 
 	skb = validate_xmit_xfrm(skb, features, again);
 
+	if (!skb_frags_readable(skb) && !dev->netmem_tx)
+		goto out_kfree_skb;
+
 	return skb;
 
 out_kfree_skb:
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 6e7cd6a5c177..6c5d62df0d65 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -972,6 +972,13 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
 		goto err_unlock;
 	}
 
+	if (!netdev->netmem_tx) {
+		err = -EOPNOTSUPP;
+		NL_SET_ERR_MSG(info->extack,
+			       "Driver does not support netmem TX");
+		goto err_unlock;
+	}
+
 	binding = net_devmem_bind_dmabuf(netdev, DMA_TO_DEVICE, dmabuf_fd,
 					 info->extack);
 	if (IS_ERR(binding)) {
-- 
2.48.1.601.g30ceb7b040-goog