> On Thu, 4 Nov 2021 18:35:33 +0100 Lorenzo Bianconi wrote:
> > -static unsigned long bpf_xdp_copy(void *dst_buff, const void *src_buff,
> > +static unsigned long bpf_xdp_copy(void *dst_buff, const void *ctx,
> > unsigned long off, unsigned long len)
> > {
> > - memcpy(dst_buff, src_buff + off, len);
> > + unsigned long base_len, copy_len, frag_off_total;
> > + struct xdp_buff *xdp = (struct xdp_buff *)ctx;
> > + struct skb_shared_info *sinfo;
> > + int i;
> > +
> > + if (likely(!xdp_buff_is_mb(xdp))) {
>
> Would it be better to do
>
> if (xdp->data_end - xdp->data >= off + len)
>
> ?
Hi Jakub,
I am fine with the patch (just a typo inline), thx :)
I will let Eelco to comment since he wrote the original code.
If there is no objections, I will integrate it in v18.
Regards,
Lorenzo
>
> > + memcpy(dst_buff, xdp->data + off, len);
> > + return 0;
> > + }
> > +
> > + base_len = xdp->data_end - xdp->data;
> > + frag_off_total = base_len;
> > + sinfo = xdp_get_shared_info_from_buff(xdp);
> > +
> > + /* If we need to copy data from the base buffer do it */
> > + if (off < base_len) {
> > + copy_len = min(len, base_len - off);
> > + memcpy(dst_buff, xdp->data + off, copy_len);
> > +
> > + off += copy_len;
> > + len -= copy_len;
> > + dst_buff += copy_len;
> > + }
> > +
> > + /* Copy any remaining data from the fragments */
> > + for (i = 0; len && i < sinfo->nr_frags; i++) {
> > + skb_frag_t *frag = &sinfo->frags[i];
> > + unsigned long frag_len, frag_off;
> > +
> > + frag_len = skb_frag_size(frag);
> > + frag_off = off - frag_off_total;
> > + if (frag_off < frag_len) {
> > + copy_len = min(len, frag_len - frag_off);
> > + memcpy(dst_buff,
> > + skb_frag_address(frag) + frag_off, copy_len);
> > +
> > + off += copy_len;
> > + len -= copy_len;
> > + dst_buff += copy_len;
> > + }
> > + frag_off_total += frag_len;
> > + }
> > +
>
> nit: can't help but feel that you can merge base copy and frag copy:
>
> sinfo = xdp_get_shared_info_from_buff(xdp);
> next_frag = &sinfo->frags[0];
> end_frag = &sinfo->frags[sinfo->nr_frags];
>
> ptr_off = 0;
> ptr_buf = xdp->data;
> ptr_len = xdp->data_end - xdp->data;
>
> while (true) {
> if (off < ptr_off + ptr_len) {
> copy_off = ptr_off - off;
I guess here should be:
copy_off = off - ptr_off;
> copy_len = min(len, ptr_len - copy_off);
> memcpy(dst_buff, ptr_buf + copy_off, copy_len);
>
> off += copy_len;
> len -= copy_len;
> dst_buff += copy_len;
> }
>
> if (!len || next_frag == end_frag)
> break;
>
> ptr_off += ptr_len;
> ptr_buf = skb_frag_address(next_frag);
> ptr_len = skb_frag_size(next_frag);
> next_frag++;
> }
>
> Up to you.
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