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? _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
