Subject: Re: [PATCH net-next v5 08/15] net-timestamp: support sw SCM_TSTAMP_SND for bpf extension

From: Martin KaFai Lau <[email-masked]>
Date: Wed, 15 Jan 2025 14:48:36 -0800

On 1/12/25 3:37 AM, Jason Xing wrote:
> Support SCM_TSTAMP_SND case. Then we will get the software
> timestamp when the driver is about to send the skb. Later, I
> will support the hardware timestamp.

> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 169c6d03d698..0fb31df4ed95 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -5578,6 +5578,9 @@ static void __skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk, int tstype
>   	case SCM_TSTAMP_SCHED:
>   		op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
>   		break;
> +	case SCM_TSTAMP_SND:
> +		op = BPF_SOCK_OPS_TS_SW_OPT_CB;

For the hwtstamps case, is skb_hwtstamps(skb) set? From looking at a few 
drivers, it does not look like it. I don't see the hwtstamps support in patch 10 
either. What did I miss ?

> +		break;
>   	default:
>   		return;
>   	}