> On Thu, Sep 03, 2020 at 10:58:51PM +0200, Lorenzo Bianconi wrote: > > From: Sameeh Jubran <same...@amazon.com> > > > > The implementation is based on this [0] draft by Jesper D. Brouer. > > > > Provided two new helpers: > > > > * bpf_xdp_get_frag_count() > > * bpf_xdp_get_frags_total_size() > > > > [0] xdp mb design - > > https://github.com/xdp-project/xdp-project/blob/master/areas/core/xdp-multi-buffer01-design.org > > Signed-off-by: Sameeh Jubran <same...@amazon.com> > > Signed-off-by: Lorenzo Bianconi <lore...@kernel.org> > > --- > > include/uapi/linux/bpf.h | 14 ++++++++++++ > > net/core/filter.c | 39 ++++++++++++++++++++++++++++++++++ > > tools/include/uapi/linux/bpf.h | 14 ++++++++++++ > > 3 files changed, 67 insertions(+) > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > > index c4a6d245619c..53db75095306 100644 > > --- a/include/uapi/linux/bpf.h > > +++ b/include/uapi/linux/bpf.h > > @@ -3590,6 +3590,18 @@ union bpf_attr { > > * > > * Return > > * 0 on success, or a negative error in case of failure.
[...]
> > +
>
> I only quickly jumped through series and IMHO this helper should be
> rewritten/optimized in a way that we bail out as early as possible if
> !xdp->mb as the rest of the code on that condition will do nothing and i'm
> not sure if compiler would optimize it.
>
>
> struct skb_shared_info *sinfo;
> int nfrags, i;
> int size = 0;
>
> if (!xdp->mb)
> return 0;
>
> sinfo = xdp_get_shared_info_from_buff(xdp);
>
> nfrags = min(sinfo->nr_frags, MAX_SKB_FRAGS);
>
> for (i = 0; i < nfrags; i++)
> size += skb_frag_size(&sinfo->frags[i]);
>
> return size;
>
> Thoughts?
I agree.
Regards,
Lorenzo
>
>
> > + return size;
> > +}
> > +
> > +const struct bpf_func_proto bpf_xdp_get_frags_total_size_proto = {
> > + .func = bpf_xdp_get_frags_total_size,
> > + .gpl_only = false,
> > + .ret_type = RET_INTEGER,
> > + .arg1_type = ARG_PTR_TO_CTX,
> > +};
> > +
> > BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset)
> > {
> > void *data_hard_end = xdp_data_hard_end(xdp); /* use xdp->frame_sz */
> > @@ -6889,6 +6924,10 @@ xdp_func_proto(enum bpf_func_id func_id, const
> > struct bpf_prog *prog)
> > return &bpf_xdp_adjust_tail_proto;
> > case BPF_FUNC_xdp_adjust_mb_header:
> > return &bpf_xdp_adjust_mb_header_proto;
> > + case BPF_FUNC_xdp_get_frag_count:
> > + return &bpf_xdp_get_frag_count_proto;
> > + case BPF_FUNC_xdp_get_frags_total_size:
> > + return &bpf_xdp_get_frags_total_size_proto;
> > case BPF_FUNC_fib_lookup:
> > return &bpf_xdp_fib_lookup_proto;
> > #ifdef CONFIG_INET
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index 392d52a2ecef..dd4669096cbb 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -3591,6 +3591,18 @@ union bpf_attr {
> > *
> > * Return
> > * 0 on success, or a negative error in case of failure.
> > + *
> > + * int bpf_xdp_get_frag_count(struct xdp_buff *xdp_md)
> > + * Description
> > + * Get the total number of frags for a given packet.
> > + * Return
> > + * The number of frags
> > + *
> > + * int bpf_xdp_get_frags_total_size(struct xdp_buff *xdp_md)
> > + * Description
> > + * Get the total size of frags for a given packet.
> > + * Return
> > + * The total size of frags for a given packet.
> > */
> > #define __BPF_FUNC_MAPPER(FN) \
> > FN(unspec), \
> > @@ -3743,6 +3755,8 @@ union bpf_attr {
> > FN(d_path), \
> > FN(copy_from_user), \
> > FN(xdp_adjust_mb_header), \
> > + FN(xdp_get_frag_count), \
> > + FN(xdp_get_frags_total_size), \
> > /* */
> >
> > /* integer value in 'imm' field of BPF_CALL instruction selects which
> > helper
> > --
> > 2.26.2
> >
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