On Sun, Jan 15, 2017 at 10:35:43AM +0200, Leon Romanovsky wrote: > On Fri, Jan 13, 2017 at 02:27:21PM -0700, Jason Gunthorpe wrote: > > On Fri, Jan 13, 2017 at 10:31:27PM +0200, Leon Romanovsky wrote: > > > > > > This is about what happens if the multicast MTU < unicast MTU - which > > > > is *exactly* the same case on RC and UD. > > > > > > > > IPoIB cannot send a 64k multicast MTU on RC either. > > > > > > Multicast is sent in datagram despite being in connected mode and for > > > datagram the MTU is limited by IB > > > > I am aware of that. Read you patch again: > > > > > + if (priv->mcast_mtu < priv->admin_mtu) > > > + ipoib_warn(priv, "MTU must be smaller than mcast_mtu (%u)\n", > > > > This check is fails in RC mode as well. > > > > And we already check if the requested MTU is beyond the port > > capability: > > > > + if (new_mtu > IPOIB_UD_MTU(priv->max_ib_mtu)) > > + return -EINVAL; > > > > So I have *no idea* why you'd want to check it against the multicast > > group too.. > > > > Port MTU capability can be higher than link MTU. In this flow, the user > can try to set manually MTU which will be higher than SM provided. > > Immediately after that print, we have a following piece of code: > 236 dev->mtu = min(priv->mcast_mtu, priv->admin_mtu); Maybe the better fix is to take that min out than generate a warning. Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
