> On 6/30/20 2:49 PM, Lorenzo Bianconi wrote:
> [...]
[...]
> > + prog = READ_ONCE(rcpu->prog);
>
> What purpose does the READ_ONCE() have here, also given you don't use it in above check?
> Since upon map update you realloc, repopulate and then xchg() the rcpu entry itself, there
> is never the case where you xchg() or WRITE_ONCE() the rcpu->prog, so what does READ_ONCE()
> serve in this context? Imho, it should probably just be deleted and plain rcpu->prog used
> to avoid confusion.
Hi Daniel,
ack, I will fix it in v6
>
> > + for (i = 0; i < n; i++) {
> > + struct xdp_frame *xdpf = frames[i];
> > + u32 act;
> > + int err;
> > +
> > + rxq.dev = xdpf->dev_rx;
> > + rxq.mem = xdpf->mem;
> > + /* TODO: report queue_index to xdp_rxq_info */
> > +
> > + xdp_convert_frame_to_buff(xdpf, &xdp);
> > +
> > + act = bpf_prog_run_xdp(prog, &xdp);
> > + switch (act) {
> > + case XDP_PASS:
> > + err = xdp_update_frame_from_buff(&xdp, xdpf);
> > + if (err < 0) {
> > + xdp_return_frame(xdpf);
> > + stats->drop++;
> > + } else {
> > + frames[nframes++] = xdpf;
> > + stats->pass++;
> > + }
> > + break;
> > + default:
> > + bpf_warn_invalid_xdp_action(act);
> > + /* fallthrough */
> > + case XDP_DROP:
> > + xdp_return_frame(xdpf);
> > + stats->drop++;
> > + break;
> > + }
> > + }
> > +
> > + xdp_clear_return_frame_no_direct();
> > +
> > + rcu_read_unlock();
> > +
> > + return nframes;
> > +}
> [...]
> > +bool cpu_map_prog_allowed(struct bpf_map *map)
> > +{
> > + return map->map_type == BPF_MAP_TYPE_CPUMAP &&
> > + map->value_size != offsetofend(struct bpf_cpumap_val, qsize);
> > +}
> > +
> > +static int __cpu_map_load_bpf_program(struct bpf_cpu_map_entry *rcpu, int fd)
> > +{
> > + struct bpf_prog *prog;
> > +
> > + prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP, false);
>
> Nit: why the _dev variant; just use bpf_prog_get_type()?
ack, I will fix in v6
Regards,
Lorenzo
>
> > + if (IS_ERR(prog))
> > + return PTR_ERR(prog);
> > +
> > + if (prog->expected_attach_type != BPF_XDP_CPUMAP) {
> > + bpf_prog_put(prog);
> > + return -EINVAL;
> > + }
> > +
> > + rcpu->value.bpf_prog.id = prog->aux->id;
> > + rcpu->prog = prog;
> > +
> > + return 0;
> > +}
> > +
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