On Wed, Apr 26, 2017 at 08:00:02PM -0400, Willem de Bruijn wrote:
> > + if (!hwtstamps && !(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW)
> > &&
> > + skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)
> > + return;
> > +
>
> This check should only happen for software transmit timestamps, so simpler to
> revise the check in sw_tx_timestamp above to
>
> if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
> - !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
> + (!(skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)) ||
> + (skb->sk && skb->sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW)
Good point. This will avoid unnecessary calls of skb_tstamp_tx() in
the common case when SOF_TIMESTAMPING_OPT_TX_SWHW will not be enabled.
> > @@ -720,6 +720,7 @@ void __sock_recv_timestamp(struct msghdr *msg, struct
> > sock *sk,
> > empty = 0;
> > if (shhwtstamps &&
> > (sk->sk_tsflags & SOF_TIMESTAMPING_RAW_HARDWARE) &&
> > + (empty || !skb_is_err_queue(skb)) &&
> > ktime_to_timespec_cond(shhwtstamps->hwtstamp, tss.ts + 2)) {
>
> I find skb->tstamp == 0 easier to understand than the condition on empty.
>
> Indeed, this is so non-obvious that I would suggest another helper function
> skb_is_hwtx_tstamp with a concise comment about the race condition
> between tx software and hardware timestamps (as in the last sentence of
> the commit message).
Should it include also the skb_is_err_queue() check? If it returned
true for both TX and RX HW timestamps, maybe it could be called
skb_has_hw_tstamp?
--
Miroslav Lichvar
