On Jun 12, 2013, at 5:34 PM, Simon Horman wrote: > On Wed, Jun 12, 2013 at 08:08:50AM -0700, Ben Pfaff wrote: >> On Wed, Jun 12, 2013 at 07:11:50AM -0700, Murphy McCauley wrote: >>> >>> On Jun 12, 2013, at 6:28 AM, Ed Maste wrote: >>> >>>> On 12 June 2013 07:04, Murphy McCauley <murphy.mccau...@gmail.com> wrote: >>>>> (Sorry this isn't an actual reply and is missing context -- I wasn't on >>>>> the list when it was originally posted.) >>>>> >>>>> Simon and I have been in touch about this, and I thought I'd share my >>>>> findings for what they're worth. >>>>> >>>>> The problem is from the commit Simon mentioned >>>>> (796223f5bc3a4896e6398733c798390158479400). Specifically, it's in >>>>> netdev-linux.c in netdev_linux_send(). >>>>> >>>>> The new version always sends using the "sender" socket made by >>>>> af_packet_sock() unless the interface is a tap, in which case it sends it >>>>> using the tap fd. This differs from the old version which sent using >>>>> whatever was in the fd field of the netdev if it was available. For tap >>>>> interfaces, this was the tap fd, so the result was the same as it is now. >>>>> But for other interfaces, this held the socket opened for receiving if >>>>> the interface was listening (which was maybe never "right" in some sense >>>>> and isn't convenient anymore since this socket descriptor is no longer >>>>> stored in the non-rx netdev). >>>>> >>>>> The comments indicate that the exception is made for tap interfaces since >>>>> writing to a tap interface with an AF_PACKET socket results in receiving >>>>> the packet you just wrote. However, I don't think this behavior is >>>>> limited to taps. Since the old version of the code sent and received >>>>> with the same socket descriptor, I think the loop was fixed by the check >>>>> in dev_queue_xmit_nit() in net/core/dev.c. Since they're two different >>>>> socket descriptors now, this no longer works and you get the loop. >>>> >>>> Ahh, it turns out Ben explained this to me when I ran into a related >>>> issue with the FreeBSD userspace implementation. Ben's message in the >>>> thread is at http://openvswitch.org/pipermail/dev/2012-July/018806.html >>>> . >>>> >>>>> I fixed it (I think) by adding a BPF packet filter on the rx socket so >>>>> that it only receives incoming packets. There's probably a better fix, >>>>> but you're welcome to the patch if you want it. >>>> >>>> I think it's worth taking a look. >>> >>> >>> I think this is more or less against master. >>> >>> diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c >>> index d73115b..cc47a6b 100644 >>> --- a/lib/netdev-linux.c >>> +++ b/lib/netdev-linux.c >>> @@ -744,6 +744,14 @@ netdev_linux_rx_open(struct netdev *netdev_, struct >>> netdev_rx **rxp) >>> } else { >>> struct sockaddr_ll sll; >>> int ifindex; >>> + /* Result of tcpdump -dd inbound */ >>> + static struct sock_filter filt[] = { >>> + { 0x28, 0, 0, 0xfffff004 }, >>> + { 0x15, 0, 1, 0x00000004 }, >>> + { 0x6, 0, 0, 0x00000000 }, >>> + { 0x6, 0, 0, 0x0000ffff } >>> + }; >>> + static struct sock_fprog fprog = {ARRAY_SIZE(filt), filt}; >>> >>> /* Create file descriptor. */ >>> fd = socket(PF_PACKET, SOCK_RAW, 0); >>> @@ -776,6 +784,16 @@ netdev_linux_rx_open(struct netdev *netdev_, struct >>> netdev_rx **rxp) >>> netdev_get_name(netdev_), strerror(error)); >>> goto error; >>> } >>> + >>> + /* Filter for only incoming packets. */ >>> + error = setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, >>> + sizeof fprog); >>> + if (error) { >>> + error = errno; >>> + VLOG_ERR("%s: failed attach filter (%s)", >>> + netdev_get_name(netdev_), strerror(error)); >>> + goto error; >>> + } >>> } >>> >>> rx = xmalloc(sizeof *rx); >> >> Thanks, Murphy. >> >> Simon, does this solve the problem you see? > > Hi Ben, Hi all, > > I have lightly tested this using the scenarios that I mentioned > in my initial post - multicast IPv6 and IPv6, broadcast ARP - and > yes, this seems to resolve the problem that I observed. > > Tested-by: Simon Horman <ho...@verge.net.au>
If you actually want this, I've submitted a slightly tweaked version: http://openvswitch.org/pipermail/dev/2013-June/028439.html _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
