Re: [PATCH] dracut-module-setup.sh: passing correct addr configuration options when using ipv6

[piliu]

On 03/01/2018 10:36 AM, Dave Young wrote:
> On 01/18/18 at 12:32pm, Pingfan Liu wrote:
> > If ssh-dump with ipv6-target-addr, kdump should wait until the ipv6 addr
> > is ready. Since dracut has implemented this function, we can pass dhcp6
> > or auto6 in cmdline to activate it.
> > But in 1st kernel, we can not know whether the ipv6 addr is got by dhcp6 or by
> > auto6 without causing side-effect (dhclient -6 will realloc addr). To
> > address it, we take the assumption that if
> > /proc/sys/net/ipv6/conf/$netdev/autoconf is enabled, then the host uses
> > auto6.
> > Signed-off-by: Pingfan Liu
> >
> > dracut-module-setup.sh |  6 ++++++
> >  kdump-lib.sh           | 12 ++++++++++++
> >  2 files changed, 18 insertions(+)
> >
> > diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> > index c0f1a88..d1dd673 100755
> > --- a/dracut-module-setup.sh
> > +++ b/dracut-module-setup.sh
> > @@ -293,6 +293,12 @@ kdump_setup_netdev() {
> >      _static=$(kdump_static_ip $_netdev $_srcaddr)
> >      if [ -n "$_static" ]; then
> >          _proto=none
> > elif is_ipv6_address $_srcaddr; then
> >    if is_ipv6_auto $_netdev; then
> >        _proto=auto6
> >    else
> >        _proto=dhcp6
> >    fi
> > else
> >        _proto=dhcp
> >    fi
> >
> > diff --git a/kdump-lib.sh b/kdump-lib.sh
> > index d981c4f..ac4dc67 100755
> > --- a/kdump-lib.sh
> > +++ b/kdump-lib.sh
> > @@ -310,6 +310,18 @@ is_atomic()
> >      grep -q "ostree" /proc/cmdline
> >  }
> >
> > +# fixme, try the best to decide whether the ipv6 addr is allocated by slaac or dhcp6
> > +is_ipv6_auto()
> > +{
> > local _netdev=$1
> > local _auto=$(cat /proc/sys/net/ipv6/conf/$_netdev/autoconf)
> > if [ $_auto -eq 1 ]; then
> >    return 0
> > else
> >    return 1
> > fi
> >
> > +}
> >
> > is_ipv6_address()
> >  {
> >      echo $1 | grep -q ":"
> > -- 
> > 2.7.4
> > _______________________________________________
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>
> Pingfan, why we did not see this problem before during test?  I remember
> we talked about this, but I can not recall the reason now.

since auto6, a kernel thread decides ipv6 addr. Usually, this kernel
thread runs and decides before the kdump service.
> BTW, does this address the 3 cases we talked about dhcp?  Just be
> curious but with auto first may be fine enough for now.

3 cases: dhcpv6/ auto6=SLAAC + dns-by-dhcp/ totally configured by Router
Advertisement. Since the last method has defect of not fully supporting
all of the dhcp functions, it is rarely used. I can not find it in
dracut param. So auto6 is enough for present. Later I can test dhcpv6 if
we have the test env.

Regards,
Pingfan