[PATCH net v2] net: orphan frags on stand-alone ptype in dev_queue_xmit_nit

[PATCH net v2] net: orphan frags on stand-alone ptype in dev_queue_xmit_nit

[Willem de Bruijn]

Zerocopy skbs frags are copied when the skb is looped to a local sock.
Commit 1080e512d44d ("net: orphan frags on receive") introduced calls
to skb_orphan_frags to deliver_skb and __netif_receive_skb for this.

With msg_zerocopy, these skbs can also exist in the tx path and thus
loop from dev_queue_xmit_nit. This already calls deliver_skb in its
loop. But it does not orphan before a separate pt_prev->func().

Add the missing skb_orphan_frags_rx.

Changes
  v1->v2: handle skb_orphan_frags_rx failure

Fixes: 1f8b977ab32d ("sock: enable MSG_ZEROCOPY")
Signed-off-by: Willem de Bruijn <willemb@google.com>
---
 net/core/dev.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 9a2254f9802f..588b473194a8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1948,8 +1948,12 @@ void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
 		goto again;
 	}
 out_unlock:
-	if (pt_prev)
-		pt_prev->func(skb2, skb->dev, pt_prev, skb->dev);
+	if (pt_prev) {
+		if (!skb_orphan_frags_rx(skb2, GFP_ATOMIC))
+			pt_prev->func(skb2, skb->dev, pt_prev, skb->dev);
+		else
+			kfree_skb(skb2);
+	}
 	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(dev_queue_xmit_nit);
-- 
2.14.1.821.g8fa685d3b7-goog

Re: [PATCH net v2] net: orphan frags on stand-alone ptype in dev_queue_xmit_nit

[Eric Dumazet]

On Fri, 2017-09-22 at 19:42 -0400, Willem de Bruijn wrote:
> Zerocopy skbs frags are copied when the skb is looped to a local sock.
> Commit 1080e512d44d ("net: orphan frags on receive") introduced calls
> to skb_orphan_frags to deliver_skb and __netif_receive_skb for this.
> 
> With msg_zerocopy, these skbs can also exist in the tx path and thus
> loop from dev_queue_xmit_nit. This already calls deliver_skb in its
> loop. But it does not orphan before a separate pt_prev->func().
> 
> Add the missing skb_orphan_frags_rx.
> 
> Changes
>   v1->v2: handle skb_orphan_frags_rx failure
> 
> Fixes: 1f8b977ab32d ("sock: enable MSG_ZEROCOPY")
> Signed-off-by: Willem de Bruijn <willemb@google.com>
> ---
>  net/core/dev.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)

Reviewed-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH net v2] net: orphan frags on stand-alone ptype in dev_queue_xmit_nit

[David Miller]

From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Sep 2017 19:42:37 -0400

> Zerocopy skbs frags are copied when the skb is looped to a local sock.
> Commit 1080e512d44d ("net: orphan frags on receive") introduced calls
> to skb_orphan_frags to deliver_skb and __netif_receive_skb for this.
> 
> With msg_zerocopy, these skbs can also exist in the tx path and thus
> loop from dev_queue_xmit_nit. This already calls deliver_skb in its
> loop. But it does not orphan before a separate pt_prev->func().
> 
> Add the missing skb_orphan_frags_rx.
> 
> Changes
>   v1->v2: handle skb_orphan_frags_rx failure
> 
> Fixes: 1f8b977ab32d ("sock: enable MSG_ZEROCOPY")
> Signed-off-by: Willem de Bruijn <willemb@google.com>

Applied and queued up for -stable, thanks.