On 12/13/24 4:02 PM, Jason Xing wrote:
On Sat, Dec 14, 2024 at 7:15 AM Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote:
On 12/13/24 7:13 AM, Jason Xing wrote:
-static void __skb_tstamp_tx_bpf(struct sock *sk, struct sk_buff *skb, int tstype)
+static void __skb_tstamp_tx_bpf(struct sock *sk, struct sk_buff *skb,
+ struct skb_shared_hwtstamps *hwtstamps,
+ int tstype)
{
+ struct timespec64 tstamp;
+ u32 args[2] = {0, 0};
int op;
if (!sk)
@@ -5552,6 +5556,11 @@ static void __skb_tstamp_tx_bpf(struct sock *sk, struct sk_buff *skb, int tstype
break;
case SCM_TSTAMP_SND:
op = BPF_SOCK_OPS_TS_SW_OPT_CB;
+ if (hwtstamps) {
+ tstamp = ktime_to_timespec64(hwtstamps->hwtstamp);
Avoid this conversion which is likely not useful to the bpf prog. Directly pass
hwtstamps->hwtstamp (in ns?) to the bpf prog. Put lower 32bits in args[0] and
higher 32bits in args[1].
It makes sense.
When replying the patch 2 thread, I noticed it may not even have to pass the
hwtstamps in args here.
Can "*skb_hwtstamps(skb) = *hwtstamps;" be done before calling the bpf prog?
Then the bpf prog can directly get it from skb_shinfo(skb)->hwtstamps.
It is like reading other fields in skb_shinfo(skb), e.g. the
skb_shinfo(skb)->tskey discussed in patch 10. The bpf prog will have a more
consistent experience in reading different fields of the skb_shinfo(skb).
skb_shinfo(skb)->hwtstamps is a more intuitive place to obtain the hwtstamp than
the broken up args[0] and args[1]. On top of that, there is also an older
"skb_hwtstamp" field in "struct bpf_sock_ops".
Right, right, last night, fortunately, I also spotted it. Let the bpf
prog parse the shared info from skb then. A new callback for hwtstamp
is needed, I suppose.
Why a new callback is needed? "*skb_hwtstamps(skb) = *hwtstamps;" cannot be done
in __skb_tstamp_tx_bpf?
