On Sat, Jan 25, 2025 at 8:47 AM Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote:
>
> On 1/20/25 5:28 PM, Jason Xing wrote:
> > In this patch, we finish the hardware part. Then bpf program can
> > fetch the hwstamp from skb directly.
> >
> > To avoid changing so many callers using SKBTX_HW_TSTAMP from drivers,
> > use this simple modification like this patch does to support printing
> > hardware timestamp.
> >
> > Signed-off-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
> > ---
> > include/linux/skbuff.h | 4 +++-
> > include/uapi/linux/bpf.h | 5 +++++
> > net/core/skbuff.c | 11 ++++++-----
> > net/dsa/user.c | 2 +-
> > net/socket.c | 2 +-
> > tools/include/uapi/linux/bpf.h | 5 +++++
> > 6 files changed, 21 insertions(+), 8 deletions(-)
> >
> > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> > index de8d3bd311f5..df2d790ae36b 100644
> > --- a/include/linux/skbuff.h
> > +++ b/include/linux/skbuff.h
> > @@ -471,7 +471,7 @@ struct skb_shared_hwtstamps {
> > /* Definitions for tx_flags in struct skb_shared_info */
> > enum {
> > /* generate hardware time stamp */
> > - SKBTX_HW_TSTAMP = 1 << 0,
> > + __SKBTX_HW_TSTAMP = 1 << 0,
> >
> > /* generate software time stamp when queueing packet to NIC */
> > SKBTX_SW_TSTAMP = 1 << 1,
> > @@ -495,6 +495,8 @@ enum {
> > SKBTX_BPF = 1 << 7,
> > };
> >
> > +#define SKBTX_HW_TSTAMP (__SKBTX_HW_TSTAMP | SKBTX_BPF)
> > +
> > #define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \
> > SKBTX_SCHED_TSTAMP | \
> > SKBTX_BPF)
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index a6d761f07f67..8936e1061e71 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -7032,6 +7032,11 @@ enum {
> > * feature is on. It indicates the
> > * recorded timestamp.
> > */
> > + BPF_SOCK_OPS_TS_HW_OPT_CB, /* Called in hardware phase when
> > + * SO_TIMESTAMPING feature is on.
>
> Same comment on the "SO_TIMESTAMPING".
>
> It will be useful to elaborate more on "hardware phase", like exactly when it
> will be called,
Got it.
>
> > + * It indicates the recorded
> > + * timestamp.
>
> and the hwtstamps will be in the skb.
Right.
>
> > + */
> > };
> >
> > /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
> > diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> > index 288eb9869827..c769feae5162 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -5548,7 +5548,7 @@ static bool skb_enable_app_tstamp(struct sk_buff *skb, int tstype, bool sw)
> > flag = SKBTX_SCHED_TSTAMP;
> > break;
> > case SCM_TSTAMP_SND:
> > - flag = sw ? SKBTX_SW_TSTAMP : SKBTX_HW_TSTAMP;
> > + flag = sw ? SKBTX_SW_TSTAMP : __SKBTX_HW_TSTAMP;
> > break;
> > case SCM_TSTAMP_ACK:
> > if (TCP_SKB_CB(skb)->txstamp_ack)
> > @@ -5565,7 +5565,8 @@ static bool skb_enable_app_tstamp(struct sk_buff *skb, int tstype, bool sw)
> > }
> >
> > static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk,
> > - int tstype, bool sw)
> > + int tstype, bool sw,
> > + struct skb_shared_hwtstamps *hwtstamps)
> > {
> > int op;
> >
> > @@ -5577,9 +5578,9 @@ 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:
> > + op = sw ? BPF_SOCK_OPS_TS_SW_OPT_CB : BPF_SOCK_OPS_TS_HW_OPT_CB;
> > if (!sw)
> > - return;
> > - op = BPF_SOCK_OPS_TS_SW_OPT_CB;
> > + *skb_hwtstamps(skb) = *hwtstamps;
>
> hwtstamps may still be NULL, no?
Right, it can be zero if something wrong happens.
Thanks,
Jason
