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Message-ID: <CAL+tcoC9Xc1-9ZJVQX+AcKaOQGPSaXhoLH7FOemsD1yNEP8ULw@mail.gmail.com>
Date: Thu, 13 Feb 2025 15:24:35 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, dsahern@...nel.org, willemdebruijn.kernel@...il.com,
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, shuah@...nel.org, ykolal@...com,
bpf@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next v10 08/12] bpf: add BPF_SOCK_OPS_TS_HW_OPT_CB callback
On Thu, Feb 13, 2025 at 7:20 AM Martin KaFai Lau <martin.lau@...ux.dev> wrote:
>
> On 2/11/25 10:18 PM, Jason Xing wrote:
> > Support hw SCM_TSTAMP_SND case for bpf timestamping.
> >
> > Add a new sock_ops callback, BPF_SOCK_OPS_TS_HW_OPT_CB. This
> > callback will occur at the same timestamping point as the user
> > space's hardware SCM_TSTAMP_SND. The BPF program can use it to
> > get the same SCM_TSTAMP_SND timestamp without modifying the
> > user-space application.
> >
> > To avoid increase the code complexity, replace SKBTX_HW_TSTAMP
> > with SKBTX_HW_TSTAMP_NOBPF instead of changing numerous callers
> > from driver side using SKBTX_HW_TSTAMP. The new definition of
> > SKBTX_HW_TSTAMP means the combination tests of socket timestamping
> > and bpf timestamping. After this patch, drivers can work under the
> > bpf timestamping.
> >
> > Considering some drivers doesn't assign the skb with hardware
> > timestamp, this patch do the assignment and then BPF program
> > can acquire the hwstamp from skb directly.
> >
> > Signed-off-by: Jason Xing <kerneljasonxing@...il.com>
> > ---
> > include/linux/skbuff.h | 4 +++-
> > include/uapi/linux/bpf.h | 4 ++++
> > net/core/skbuff.c | 6 +++---
> > tools/include/uapi/linux/bpf.h | 4 ++++
> > 4 files changed, 14 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> > index 76582500c5ea..0b4f1889500d 100644
> > --- a/include/linux/skbuff.h
> > +++ b/include/linux/skbuff.h
> > @@ -470,7 +470,7 @@ 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_NOBPF = 1 << 0,
> >
> > /* generate software time stamp when queueing packet to NIC */
> > SKBTX_SW_TSTAMP = 1 << 1,
> > @@ -494,6 +494,8 @@ enum {
> > SKBTX_BPF = 1 << 7,
> > };
> >
> > +#define SKBTX_HW_TSTAMP (SKBTX_HW_TSTAMP_NOBPF | 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 b3bd92281084..f70edd067edf 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -7043,6 +7043,10 @@ enum {
> > * to the nic when SK_BPF_CB_TX_TIMESTAMPING
> > * feature is on.
> > */
> > + BPF_SOCK_OPS_TS_HW_OPT_CB, /* Called in hardware phase when
> > + * SK_BPF_CB_TX_TIMESTAMPING feature
> > + * is on.
> > + */
> > };
> >
> > /* 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 d80d2137692f..4930c43ee77b 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -5547,7 +5547,7 @@ static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb,
> > case SCM_TSTAMP_SCHED:
> > return skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP;
> > case SCM_TSTAMP_SND:
> > - return skb_shinfo(skb)->tx_flags & (hwts ? SKBTX_HW_TSTAMP :
> > + return skb_shinfo(skb)->tx_flags & (hwts ? SKBTX_HW_TSTAMP_NOBPF :
> > SKBTX_SW_TSTAMP);
> > case SCM_TSTAMP_ACK:
> > return TCP_SKB_CB(skb)->txstamp_ack;
> > @@ -5568,9 +5568,9 @@ static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb,
> > op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
> > break;
> > case SCM_TSTAMP_SND:
> > + op = hwts ? BPF_SOCK_OPS_TS_HW_OPT_CB : BPF_SOCK_OPS_TS_SW_OPT_CB;
>
> Remove this "hwts" test.
>
> > if (hwts)
>
> Reuse this and do everything in this "if else" statement.
Will do it.
Thanks,
Jason
>
> > - return;
> > - op = BPF_SOCK_OPS_TS_SW_OPT_CB;
> > + *skb_hwtstamps(skb) = *hwts;
> > break;
> > default:
> > return;
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index 9bd1c7c77b17..7b9652ce7e3c 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -7033,6 +7033,10 @@ enum {
> > * to the nic when SK_BPF_CB_TX_TIMESTAMPING
> > * feature is on.
> > */
> > + BPF_SOCK_OPS_TS_HW_OPT_CB, /* Called in hardware phase when
> > + * SK_BPF_CB_TX_TIMESTAMPING feature
> > + * is on.
> > + */
> > };
> >
> > /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
>
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