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Re: [PATCH] xfrm: dst_entries_init() per-net dst_ops

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On Wed, Oct 28, 2015 at 9:42 AM, Hannes Frederic Sowa
<hannes@stressinduktion.org> wrote:
> Hello,
>
> On Wed, Oct 28, 2015, at 14:32, Dan Streetman wrote:
>> On Tue, Oct 27, 2015 at 12:15 PM,  <dan.streetman@canonical.com> wrote:
>> > From: Dan Streetman <dan.streetman@canonical.com>
>> >
>> > The ipv4 and ipv6 xfrms each create a template dst_ops object, and
>> > perform dst_entries_init() on the template objects.  Then each net
>> > namespace has its net.xfrm.xfrm[46]_dst_ops field set to the template
>> > values.  The problem with that is the dst_ops.pcpuc_entries field is
>> > a percpu counter and cannot be used correctly by simply copying it to
>> > another object.
>
> How hard would it be to split of the counters from the dst_ops struct?
> We could make dst_ops instances const and have normal pointers to them
> and keep the dst_entries as a small array in net namespace?

Well, the dst_ops->pcpuc_entries counter is used in dst.c which just
gets a struct dst_ops *, so it doesn't have access to the owning net
namespace.  And, not all dst_ops users have a per-net-namespace
dst_ops; ipv4/route.c for example uses a global "ipv4_dst_ops" object.
So it probably does need to stay owned by dst_ops.


>
> Bye,
> Hannes
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Thread

[PATCH] xfrm: dst_entries_init() per-net dst_ops dan.streetman@canonical.com - 2015-10-27 17:20 +0100
  Re: [PATCH] xfrm: dst_entries_init() per-net dst_ops Dan Streetman <dan.streetman@canonical.com> - 2015-10-28 14:40 +0100
    Re: [PATCH] xfrm: dst_entries_init() per-net dst_ops Hannes Frederic Sowa <hannes@stressinduktion.org> - 2015-10-28 14:50 +0100
      Re: [PATCH] xfrm: dst_entries_init() per-net dst_ops Dan Streetman <dan.streetman@canonical.com> - 2015-10-28 16:10 +0100
    Re: [PATCH] xfrm: dst_entries_init() per-net dst_ops David Miller <davem@davemloft.net> - 2015-10-28 15:00 +0100
  [PATCHv2] xfrm: dst_entries_init() per-net dst_ops Dan Streetman <dan.streetman@canonical.com> - 2015-10-29 12:40 +0100
    Re: [PATCHv2] xfrm: dst_entries_init() per-net dst_ops kbuild test robot <lkp@intel.com> - 2015-10-29 13:00 +0100
      Re: [PATCHv2] xfrm: dst_entries_init() per-net dst_ops Dan Streetman <dan.streetman@canonical.com> - 2015-10-29 14:50 +0100
    [PATCHv3] xfrm: dst_entries_init() per-net dst_ops Dan Streetman <dan.streetman@canonical.com> - 2015-10-29 15:00 +0100

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