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 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 -- To unsubscribe from this list: send the line "unsubscribe lvs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
