Re: [Xenomai] Kernel oops during rtnet loopback usage on x86_64 (e1000e)

[Pintu Kumar <pintu.ping@gmail.com>]

> As a workaround, run the kernel with nosmap.
OK, I guessed it correctly and tried with kernel commandline "nosmap".
Because it works normally on virtual box.

With "nosmap" I don't see any kernel oops, but there are no prints either.
I mean in my rtnet-server/client, I have given some print statement.
But I am not seeing those print statement coming on the console now.
The print statements are coming for normal "xeno_task" application.

Is there any clue for this ?


Thanks,
Pintu





On Thu, Jun 21, 2018 at 8:27 PM Jan Kiszka <jan.kiszka@siemens.com> wrote:
>
> On 2018-06-21 15:41, Jan Kiszka wrote:
> > On 2018-06-21 13:55, Jan Kiszka wrote:
> >> On 2018-06-21 13:20, Pintu Kumar wrote:
> >>> Dear Jan, Greg,
> >>>
> >>> Is there any pointer about this issue?
> >>> This is blocking my next work..
> >>
> >> Does this solve the issue AND still generate valid UDP checksums (please
> >> check with wireshark or against a normal networking stack?
> >>
> >> diff --git a/kernel/drivers/net/stack/ipv4/udp/udp.c b/kernel/drivers/net/stack/ipv4/udp/udp.c
> >> index 8e80d3e0b..bb0b0fc12 100644
> >> --- a/kernel/drivers/net/stack/ipv4/udp/udp.c
> >> +++ b/kernel/drivers/net/stack/ipv4/udp/udp.c
> >> @@ -556,18 +556,17 @@ static int rt_udp_getfrag(const void *p, unsigned char *to,
> >>      if (offset)
> >>          return rtnet_read_from_iov(ufh->fd, ufh->iov, ufh->iovlen, to, fraglen);
> >>
> >> -    /* Checksum of the complete data part of the UDP message: */
> >> -    for (i = 0; i < ufh->iovlen; i++) {
> >> -            ufh->wcheck = csum_partial(ufh->iov[i].iov_base, ufh->iov[i].iov_len,
> >> -                                       ufh->wcheck);
> >> -    }
> >> -
> >>      ret = rtnet_read_from_iov(ufh->fd, ufh->iov, ufh->iovlen,
> >>                            to + sizeof(struct udphdr),
> >>                            fraglen - sizeof(struct udphdr));
> >>      if (ret)
> >>          return ret;
> >>
> >> +    /* Checksum of the complete data part of the UDP message: */
> >> +    ufh->wcheck = csum_partial(to + sizeof(struct udphdr),
> >> +                           fraglen - sizeof(struct udphdr),
> >> +                           ufh->wcheck);
> >> +
> >>      /* Checksum of the udp header: */
> >>      ufh->wcheck = csum_partial((unsigned char *)ufh,
> >>                             sizeof(struct udphdr), ufh->wcheck);
> >>
> >
> > This was definitely wrong. Here is another try:
> >
> > diff --git a/kernel/drivers/net/stack/ipv4/udp/udp.c b/kernel/drivers/net/stack/ipv4/udp/udp.c
> > index 8e80d3e0b..6cf1d369e 100644
> > --- a/kernel/drivers/net/stack/ipv4/udp/udp.c
> > +++ b/kernel/drivers/net/stack/ipv4/udp/udp.c
> > @@ -549,6 +549,7 @@ static int rt_udp_getfrag(const void *p, unsigned char *to,
> >                            unsigned int offset, unsigned int fraglen)
> >  {
> >      struct udpfakehdr *ufh = (struct udpfakehdr *)p;
> > +    unsigned int datalen = 0;
> >      int i, ret;
> >
> >
> > @@ -556,18 +557,18 @@ static int rt_udp_getfrag(const void *p, unsigned char *to,
> >      if (offset)
> >           return rtnet_read_from_iov(ufh->fd, ufh->iov, ufh->iovlen, to, fraglen);
> >
> > -    /* Checksum of the complete data part of the UDP message: */
> > -    for (i = 0; i < ufh->iovlen; i++) {
> > -            ufh->wcheck = csum_partial(ufh->iov[i].iov_base, ufh->iov[i].iov_len,
> > -                                       ufh->wcheck);
> > -    }
> > -
> >      ret = rtnet_read_from_iov(ufh->fd, ufh->iov, ufh->iovlen,
> >                             to + sizeof(struct udphdr),
> >                             fraglen - sizeof(struct udphdr));
> >      if (ret)
> >           return ret;
> >
> > +    /* Checksum of the complete data part of the UDP message: */
> > +    for (i = 0; i < ufh->iovlen; i++)
> > +         datalen += ufh->iov[i].iov_len;
> > +    ufh->wcheck = csum_partial(to + sizeof(struct udphdr), datalen,
> > +                            ufh->wcheck);
> > +
> >      /* Checksum of the udp header: */
> >      ufh->wcheck = csum_partial((unsigned char *)ufh,
> >                              sizeof(struct udphdr), ufh->wcheck);
> >
>
> OK, this won't work either if fraglen < datalen. We have to rework this
> more fundamentally.
>
> As a workaround, run the kernel with nosmap.
>
> Jan