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On Wed, Dec 24, 2008 at 02:51:18PM +1100, Simon Horman wrote:
> On Mon, Dec 08, 2008 at 09:40:12PM +0000, Daniel Drown wrote:
> > I have a need for multiple local nodes in LVS. I started from the patch
> > from
> > 2005:
> > http://archive.linuxvirtualserver.org/html/lvs-users/2005-06/msg00113.html
> >
> > I found three problems with it:
> > 1. packet checksums were not calculated correctly
> > 2. having stats enabled would deadlock the kernel in the stats update
> > function
> > (ip_vs_in_stats/ip_vs_out_stats)
> > 3. the kernel would deadlock in the packet recieve function (ip_vs_in)
> >
> > For #1, I believe this was because the existing code assumes the TCP/UDP
> > checksums are correct (which is not true for locally generated packets with
> > hardware checksum). I just used the same code that the tcp and udp
> > functions
> > use.
> >
> > For #2 and #3, the problem was that the majority of the code runs as a
> > bottom
> > handler. Locally generated packets are run as a normal kernel context. If
> > a
> > network interrupt happens while the kernel is holding a IPVS lock for
> > sending
> > a local packet, it can schedule the bottom handler. The bottom handler can
> > then try to acquire the same lock, and this is a deadlock. To prevent this
> > from happening, I've disabled bottom handlers (local_bh_disable) in the
> > local
> > packet output function I created (ip_vs_out_nobh).
> >
> > I've tested this and it works on a RH5/CentOS5 2.6.18.92.1.17.el5 kernel:
> > http://dan.drown.org/software/ipvs-2.6.18-92.1.17.el5-multiple-local-nodes.patch
> >
> > I've ported it to a stock 2.6.27.7 kernel, but I haven't had time to test it
> > out yet:
> > http://dan.drown.org/software/ipvs-2.6.27.7-multiple-local-nodes.patch
> >
> > I welcome any comments or criticism on the code.
>
> Hi Daniel,
>
> sorry to take so long to respond, I have been meaning to do so.
>
> Your patch seems good to me (though I am somewhat biases as I wrote
> the patch you based your patch on). Would it be possible for you to
>
> a) update the code to either DaveM's net-next-2.6 tree on git.kernel.org,
> or at the very least one of the 2.6.29-rc releases? In particular
Sorry, that should be one of the 2.6.28-rc releases.
> please note that the lvs code has moved from net/ipv4/ipvs/ to
> net/netfilter/ipvs/ . Also, I think that you will need to rework
> your checksum code changes a little to accomodate IPv6, which
> has been merged into IPVS recently.
>
> b) Provide a Signed-off-by line, an explanation of which can be found at
> http://linux.yyz.us/patch-format.html
>
> --
> Simon Horman
> VA Linux Systems Japan K.K., Sydney, Australia Satellite Office
> H: www.vergenet.net/~horms/ W: www.valinux.co.jp/en
>
--
Simon Horman
VA Linux Systems Japan K.K., Sydney, Australia Satellite Office
H: www.vergenet.net/~horms/ W: www.valinux.co.jp/en
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