net-timestamp: no-payload option

Add timestamping option SOF_TIMESTAMPING_OPT_TSONLY. For transmit timestamps, this loops timestamps on top of empty packets. Doing so reduces the pressure on SO_RCVBUF. Payload inspection and cmsg reception (aside from timestamps) are no longer possible. This works together with a follow on patch that allows administrators to only allow tx timestamping if it does not loop payload or metadata. Signed-off-by: Willem de Bruijn <willemb@google.com> ---- Changes (rfc -> v1) - add documentation - remove unnecessary skb->len test (thanks to Richard Cochran) Signed-off-by: David S. Miller <davem@davemloft.net>

Willem de Bruijn committed 11 years ago

Commit 49ca0d81 parent 9766e976 files · +48 −12Browse files

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include/uapi/linux/net_tstamp.h+2−1

@@ -24,8 +24,9 @@ enum { · 23 unmodified lines
24	24	SOF_TIMESTAMPING_TX_SCHED = (1<<8),
25	25	SOF_TIMESTAMPING_TX_ACK = (1<<9),
26	26	SOF_TIMESTAMPING_OPT_CMSG = (1<<10),
	27	+ SOF_TIMESTAMPING_OPT_TSONLY = (1<<11),
27	28
28		− SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_CMSG,
	29	+ SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_TSONLY,
29	30	SOF_TIMESTAMPING_MASK = (SOF_TIMESTAMPING_LAST - 1) \|
30	31	SOF_TIMESTAMPING_LAST
31	32	};