Re: [PATCH bpf-next] selftests/bpf: Properly enable hwtstamp in xdp_hw_metadata

[Stanislav Fomichev <sdf@xxxxxxxxxx>]

On Wed, Jan 25, 2023 at 5:12 PM Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote:
>
> On 1/25/23 2:32 PM, Stanislav Fomichev wrote:
> > The existing timestamping_enable() is a no-op because it applies
> > to the socket-related path that we are not verifying here
> > anymore. (but still leaving the code around hoping we can
> > have xdp->skb path verified here as well)
> >
> >    poll: 1 (0)
> >    xsk_ring_cons__peek: 1
> >    0xf64788: rx_desc[0]->addr=100000000008000 addr=8100 comp_addr=8000
> >    rx_hash: 3697961069
> >    rx_timestamp:  1674657672142214773 (sec:1674657672.1422)
> >    XDP RX-time:   1674657709561774876 (sec:1674657709.5618) delta sec:37.4196
> >    AF_XDP time:   1674657709561871034 (sec:1674657709.5619) delta
> > sec:0.0001 (96.158 usec)
> >    0xf64788: complete idx=8 addr=8000
> >
> > Also, maybe something to archive here, see [0] for Jesper's note
> > about NIC vs host clock delta.
> >
> > 0: https://lore.kernel.org/bpf/f3a116dc-1b14-3432-ad20-a36179ef0608@xxxxxxxxxx/
> >
> > Fixes: 297a3f124155 ("selftests/bpf: Simple program to dump XDP RX metadata")
> > Reported-by: Jesper Dangaard Brouer <jbrouer@xxxxxxxxxx>
> > Tested-by: Jesper Dangaard Brouer <jbrouer@xxxxxxxxxx>
> > Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> > ---
> >   tools/testing/selftests/bpf/xdp_hw_metadata.c | 28 ++++++++++++++++++-
> >   1 file changed, 27 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> > index 0008f0f239e8..dc899c53db5e 100644
> > --- a/tools/testing/selftests/bpf/xdp_hw_metadata.c
> > +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> > @@ -24,6 +24,7 @@
> >   #include <linux/net_tstamp.h>
> >   #include <linux/udp.h>
> >   #include <linux/sockios.h>
> > +#include <linux/net_tstamp.h>
> >   #include <sys/mman.h>
> >   #include <net/if.h>
> >   #include <poll.h>
> > @@ -278,13 +279,36 @@ static int rxq_num(const char *ifname)
> >
> >       ret = ioctl(fd, SIOCETHTOOL, &ifr);
> >       if (ret < 0)
> > -             error(-1, errno, "socket");
> > +             error(-1, errno, "ioctl(SIOCETHTOOL)");
> >
> >       close(fd);
> >
> >       return ch.rx_count + ch.combined_count;
> >   }
> >
> > +static void hwtstamp_enable(const char *ifname)
> > +{
> > +     struct hwtstamp_config cfg = {
> > +             .rx_filter = HWTSTAMP_FILTER_ALL,
> > +     };
> > +
> > +     struct ifreq ifr = {
> > +             .ifr_data = (void *)&cfg,
> > +     };
> > +     strcpy(ifr.ifr_name, ifname);
> > +     int fd, ret;
> > +
> > +     fd = socket(AF_UNIX, SOCK_DGRAM, 0);
> > +     if (fd < 0)
> > +             error(-1, errno, "socket");
> > +
> > +     ret = ioctl(fd, SIOCSHWTSTAMP, &ifr);
> > +     if (ret < 0)
> > +             error(-1, errno, "ioctl(SIOCSHWTSTAMP)");
> > +
> > +     close(fd);
> > +}
> > +
> >   static void cleanup(void)
> >   {
> >       LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
> > @@ -341,6 +365,8 @@ int main(int argc, char *argv[])
> >
> >       printf("rxq: %d\n", rxq);
> >
> > +     hwtstamp_enable(ifname);
>
> Will it to restore to the earlier setting when the process exits?

Nope, do you think we should? Probably a good idea, let me add that...