On Tue, Apr 19, 2016 at 01:32:14AM -0400, Soheil Hassas Yeganeh wrote:
> > + TCP_SKB_CB(skb)->txstamp_ack =
> > + !!(shinfo->tx_flags & SKBTX_ACK_TSTAMP);
>
> Maybe we can skip a conditional jump here (because of !!), by simply
> using the cached bit in next_skb:
> TCP_SKB_CB(skb)->txstamp_ack = TCP_SKB_CB(next_skb)->txstamp_ack;
Recall the tx_flags are merged/combined (and so should be the txstamp_ack).
Would there be a case that TCP_SKB_CB(skb)->txstamp_ack is 1 and
TCP_SKB_CB(next_skb)->txstamp_ack is 0?
I can change it like the following which may help in showing the intention:
if (TCP_SKB_CB(next_skb)->txstamp_ack)
TCP_SKB_CB(skb)->txstamp_ack = 1;
A bit off topic, I feel like the SKBTX_ACK_TSTAMP and txstamp_ack are sort
of redundant but I have not look into the details yet, so not completely
sure. It wwould be a separate cleanup patch if it is the case.
