Re: [PATCH bpf-next v12 01/12] bpf: add networking timestamping support to bpf_get/setsockopt()

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

Jason Xing wrote:
> The new SK_BPF_CB_FLAGS and new SK_BPF_CB_TX_TIMESTAMPING are
> added to bpf_get/setsockopt. The later patches will implement the
> BPF networking timestamping. The BPF program will use
> bpf_setsockopt(SK_BPF_CB_FLAGS, SK_BPF_CB_TX_TIMESTAMPING) to
> enable the BPF networking timestamping on a socket.
> 
> Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
> ---
>  include/net/sock.h             |  3 +++
>  include/uapi/linux/bpf.h       |  8 ++++++++
>  net/core/filter.c              | 23 +++++++++++++++++++++++
>  tools/include/uapi/linux/bpf.h |  1 +
>  4 files changed, 35 insertions(+)
> 
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 8036b3b79cd8..7916982343c6 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -303,6 +303,7 @@ struct sk_filter;
>    *	@sk_stamp: time stamp of last packet received
>    *	@sk_stamp_seq: lock for accessing sk_stamp on 32 bit architectures only
>    *	@sk_tsflags: SO_TIMESTAMPING flags
> +  *	@sk_bpf_cb_flags: used in bpf_setsockopt()
>    *	@sk_use_task_frag: allow sk_page_frag() to use current->task_frag.
>    *			   Sockets that can be used under memory reclaim should
>    *			   set this to false.
> @@ -445,6 +446,8 @@ struct sock {
>  	u32			sk_reserved_mem;
>  	int			sk_forward_alloc;
>  	u32			sk_tsflags;
> +#define SK_BPF_CB_FLAG_TEST(SK, FLAG) ((SK)->sk_bpf_cb_flags & (FLAG))
> +	u32			sk_bpf_cb_flags;
>  	__cacheline_group_end(sock_write_rxtx);

So far only one bit is defined. Does this have to be a 32-bit field in
every socket?

Sorry for the late notice. I had not followed the BPF part closely, as
that is not my expertise.