From: Patrick Ohly <redacted>
Date: Mon, 01 Jun 2009 21:47:22 +0200

On Fri, 2009-05-29 at 23:44 +0930, Rusty Russell wrote:

quoted

This patch adds skb_orphan to the start of dev_hard_start_xmit(): it
can be premature in the NETDEV_TX_BUSY case, but that's uncommon.

Would it be possible to make the new skb_orphan() at the start of
dev_hard_start_xmit() conditionally so that it is not executed for
packets that are to be time stamped?

As discussed before
(http://article.gmane.org/gmane.linux.network/121378/), the skb->sk
socket pointer is required for sending back the send time stamp from
inside the device driver. Calling skb_orphan() unconditionally as in
this patch would break the hardware time stamping of outgoing packets.

Indeed, we need to check that case, at a minimum.

And there are other potentially other problems.  For example, I
wonder how this interacts with the new TX MMAP af_packet support
in net-next-2.6 :-/