From: ebiederm@xmission•com (Eric W. Biederman)
To: Cong Wang <amwang@redhat•com>
Cc: netdev@vger•kernel.org, "David S. Miller" <davem@davemloft•net>
Subject: Re: [Patch net-next v2] pktgen: support net namespace
Date: Mon, 28 Jan 2013 20:17:10 -0800 [thread overview]
Message-ID: <87y5fchbcp.fsf@xmission.com> (raw)
In-Reply-To: <1359431677.20729.18.camel@cr0> (Cong Wang's message of "Tue, 29 Jan 2013 11:54:37 +0800")
Cong Wang <amwang@redhat•com> writes:
> On Mon, 2013-01-28 at 19:33 -0800, Eric W. Biederman wrote:
>> Cong Wang <amwang@redhat•com> writes:
>>
>> > On Mon, 2013-01-28 at 18:36 -0800, Eric W. Biederman wrote:
>> >> Cong Wang <amwang@redhat•com> writes:
>> >>
>> >> > From: Cong Wang <amwang@redhat•com>
>> >> >
>> >> > v2: remove a useless check
>> >> >
>> >> > This patch add net namespace to pktgen, so that
>> >> > we can use pktgen in different namespaces.
>> >> >
>> >> > Cc: Eric W. Biederman <ebiederm@xmission•com>
>> >> > Cc: David S. Miller <davem@davemloft•net>
>> >> > Signed-off-by: Cong Wang <amwang@redhat•com>
>> >> >
>> >> > ---
>> >> > net/core/pktgen.c | 123 +++++++++++++++++++++++++++++++++++------------------
>> >> > 1 files changed, 81 insertions(+), 42 deletions(-)
>> >>
>> >> Skiming through this again I have spotted what looks like a pretty
>> >> major bug. You are limiting yourself to one network device per network
>> >> namespace when the actual limit is one network device per thread.
>> >>
>> >> I think you can just kill the dev member of pktgen_net and the two or
>> >> three lines of code that touch it.
>> >
>> > Good point!
>> >
>> > It is used by pktgen_device_event() to check if the device generates the
>> > event is the one in our namespace.
>>
>> Which of course is trivial with dev_net()...;
>>
>> > It is safe to continue the search even if it is not in our namespace,
>> > but it is not efficient. Probably we need to make pktgen_threads list
>> > per-namespace.
>>
>> Having looked at the code a bit more I think the solution really is to
>> make the proc files per network namespace as you are doing, but to leave
>> the threads per cpu. Then it is just a matter of adding for_each_net
>> loops in the in the paths that add and remove the proc files.
>
> Hmm?
>
> pktgen creates each thread/proc file for each cpu, since proc files are
> per-namespace, we will have nr_cpu*nr_ns such proc files and threads.
I was thinking in pktgen_create_thread to do something like:
for_each_net(net) {
struct pktgen_net *pn = net_generic(net, pg_net_id);
pe = proc_create_data(t->tsk->comm, 0600, pn->proc_dir,
&pktgen_thread_fops, t);
if (!pe) {
....
}
}
And in pktgen_thread_write do something like:
struct pktgen_net *pn = net_generic(current->nsproxy->net_ns, pg_net_id);
pktgen_add_device(pn, t, f);
Using the seq_net infrastructure you can avoid using current but that
is not necessary to illustrate the basic idea.
> It hard to improve this due to this kind of design.
Whatever works but I don't think it looks that hard.
> I already finished v3 patch which makes pktgen_threads list per-ns, so
> far it works well. I am still testing it.
Fair enough. Working code is a good place to start.
Eric
prev parent reply other threads:[~2013-01-29 4:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-29 1:53 [Patch net-next v2] pktgen: support net namespace Cong Wang
2013-01-29 2:36 ` Eric W. Biederman
2013-01-29 3:02 ` Cong Wang
2013-01-29 3:33 ` Eric W. Biederman
2013-01-29 3:54 ` Cong Wang
2013-01-29 4:17 ` Eric W. Biederman [this message]
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