Re: [PATCH net-next] net: add a helper to avoid issues with HW TX timestamping and SO_TXTIME

Vladimir Oltean [off-list ref] writes:

As explained in commit 29d98f54a4fe ("net: enetc: allow hardware
timestamping on TX queues with tc-etf enabled"), hardware TX
timestamping requires an skb with skb->tstamp = 0. When a packet is sent
with SO_TXTIME, the skb->skb_mstamp_ns corrupts the value of skb->tstamp,
so the drivers need to explicitly reset skb->tstamp to zero after
consuming the TX time.

Create a helper named skb_txtime_consumed() which does just that. All
drivers which offload TC_SETUP_QDISC_ETF should implement it, and it

nitpick: to my ears, it seems that you meant "call"/"use" instead of
"implement".

would make it easier to assess during review whether they do the right
thing in order to be compatible with hardware timestamping or not.

Suggested-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
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Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>


Cheers,
-- 
Vinicius