Re: [PATCH bpf-next v8 06/12] bpf: support SCM_TSTAMP_SCHED of SO_TIMESTAMPING

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Jason Xing wrote:
> Introducing SKBTX_BPF is used as an indicator telling us whether
> the skb should be traced by the bpf prog.

Should this say support the SCM_TSTAMP_SCHED case?

Also: imperative mood: Introduce instead of Introducing.

 
> Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
> ---
>  include/linux/skbuff.h         |  6 +++++-
>  include/uapi/linux/bpf.h       |  4 ++++
>  net/core/dev.c                 |  3 ++-
>  net/core/skbuff.c              | 20 ++++++++++++++++++++
>  tools/include/uapi/linux/bpf.h |  4 ++++
>  5 files changed, 35 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index dfc419281cc9..35c2e864dd4b 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -490,10 +490,14 @@ enum {
>  
>  	/* generate software time stamp when entering packet scheduling */
>  	SKBTX_SCHED_TSTAMP = 1 << 6,
> +
> +	/* used for bpf extension when a bpf program is loaded */
> +	SKBTX_BPF = 1 << 7,
>  };
>  
>  #define SKBTX_ANY_SW_TSTAMP	(SKBTX_SW_TSTAMP    | \
> -				 SKBTX_SCHED_TSTAMP)
> +				 SKBTX_SCHED_TSTAMP | \
> +				 SKBTX_BPF)
>  #define SKBTX_ANY_TSTAMP	(SKBTX_HW_TSTAMP | \
>  				 SKBTX_HW_TSTAMP_USE_CYCLES | \
>  				 SKBTX_ANY_SW_TSTAMP)
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 6116eb3d1515..30d2c078966b 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -7032,6 +7032,10 @@ enum {
>  					 * by the kernel or the
>  					 * earlier bpf-progs.
>  					 */
> +	BPF_SOCK_OPS_TS_SCHED_OPT_CB,	/* Called when skb is passing through
> +					 * dev layer 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/dev.c b/net/core/dev.c
> index d77b8389753e..4f291459d6b1 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -4500,7 +4500,8 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
>  	skb_reset_mac_header(skb);
>  	skb_assert_len(skb);
>  
> -	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
> +	if (unlikely(skb_shinfo(skb)->tx_flags &
> +		     (SKBTX_SCHED_TSTAMP | SKBTX_BPF)))
>  		__skb_tstamp_tx(skb, NULL, NULL, skb->sk, true, SCM_TSTAMP_SCHED);
>  
>  	/* Disable soft irqs for various locks below. Also
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 6042961dfc02..b7261e886529 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -5564,6 +5564,21 @@ static bool skb_enable_app_tstamp(struct sk_buff *skb, int tstype, bool sw)
>  	return false;
>  }
>  
> +static void skb_tstamp_tx_bpf(struct sk_buff *skb, struct sock *sk, int tstype)
> +{
> +	int op;
> +
> +	switch (tstype) {
> +	case SCM_TSTAMP_SCHED:
> +		op = BPF_SOCK_OPS_TS_SCHED_OPT_CB;
> +		break;
> +	default:
> +		return;
> +	}
> +
> +	bpf_skops_tx_timestamping(sk, skb, op);
> +}
> +
>  void __skb_tstamp_tx(struct sk_buff *orig_skb,
>  		     const struct sk_buff *ack_skb,
>  		     struct skb_shared_hwtstamps *hwtstamps,
> @@ -5576,6 +5591,11 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
>  	if (!sk)
>  		return;
>  
> +	/* bpf extension feature entry */
> +	if (skb_shinfo(orig_skb)->tx_flags & SKBTX_BPF)
> +		skb_tstamp_tx_bpf(orig_skb, sk, tstype);
> +
> +	/* application feature entry */
>  	if (!skb_enable_app_tstamp(orig_skb, tstype, sw))
>  		return;
>  
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 70366f74ef4e..eed91b7296b7 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -7025,6 +7025,10 @@ enum {
>  					 * by the kernel or the
>  					 * earlier bpf-progs.
>  					 */
> +	BPF_SOCK_OPS_TS_SCHED_OPT_CB,	/* Called when skb is passing through
> +					 * dev layer 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
> -- 
> 2.43.5
>