netdev - Re: [PATCH bpf-next v8 08/12] bpf: support hw SCM_TSTAMP_SND of SO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAL+tcoBMVfcmdvwAOe5QROweKnMQw4NrrBwtQZ6RZYD4xEX_3g@mail.gmail.com>
Date: Tue, 11 Feb 2025 08:00:29 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>, davem@...emloft.net, 
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, dsahern@...nel.org, 
	willemb@...gle.com, ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	eddyz87@...il.com, song@...nel.org, yonghong.song@...ux.dev, 
	john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me, 
	haoluo@...gle.com, jolsa@...nel.org, horms@...nel.org, bpf@...r.kernel.org, 
	netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next v8 08/12] bpf: support hw SCM_TSTAMP_SND of SO_TIMESTAMPING

On Tue, Feb 11, 2025 at 6:40 AM Martin KaFai Lau <martin.lau@...ux.dev> wrote:
>
> On 2/5/25 8:03 AM, Jason Xing wrote:
> >>> @@ -5574,9 +5575,9 @@ static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk,
> >>>                op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
> >>>                break;
> >>>        case SCM_TSTAMP_SND:
> >>> -             if (!sw)
> >>> -                     return;
> >>> -             op = BPF_SOCK_OPS_TS_SW_OPT_CB;
> >>> +             op = sw ? BPF_SOCK_OPS_TS_SW_OPT_CB : BPF_SOCK_OPS_TS_HW_OPT_CB;
> >>> +             if (!sw && hwtstamps)
> >>> +                     *skb_hwtstamps(skb) = *hwtstamps;
> >> Isn't this called by drivers that have actually set skb_hwtstamps?
> > Oops, somehow my mind has gone blank 🙁 Will remove it. Thanks for
> > correcting me!
>
> I just noticed I missed this thread when reviewing v9.
>
> I looked at a few drivers, e.g. the mlx5e_consume_skb(). It does not necessarily

There are indeed many drivers behaving like you said:
1. xgbe_tx_tstamp()
2. aq_ptp_tx_hwtstamp()
3. bnx2x_ptp_task
4. i40e_ptp_tx_hwtstamp
...

I really doubt that I've checked this a long time ago and then left
this memory behind in V9, after all we've discussed this a lot of
times...

> set the skb_hwtstamps(skb) before calling skb_tstamp_tx(). The __skb_tstamp_tx()
> is also setting skb_hwtstamps(skb) after testing "if (hwtstamps)", so I think

This assignment is used to assign a cloned or newly allocated skb
instead of the orig_skb passing from the driver side.

> this assignment is still needed here?

Right.

Thanks,
Jason