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

On Wed, Mar 10, 2021 at 07:16:26AM -0800, Richard Cochran wrote:

On Wed, Mar 10, 2021 at 04:50:44PM +0200, Vladimir Oltean wrote:

quoted

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

Bikeshedding about the name: "consumed" suggests much more to me than
what is going on.

How about this?   skb_reset_txtime();

Not really a native speaker, but what more does it suggest? As far as
the Ethernet driver is concerned, it needs to consume the TX time (by
putting it into the TX buffer descriptor or whatever) and say it did
that. From the perspective of a driver writer I think it is intuitive to
have it called that way.