From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
markb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org,
majd-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org,
matanb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org
Subject: Re: [PATCH rdma-next 4/4] IB/core: Add IP to GID netlink offload
Date: Wed, 4 May 2016 12:52:41 -0600 [thread overview]
Message-ID: <20160504185241.GD20554@obsidianresearch.com> (raw)
In-Reply-To: <1462376518-6725-5-git-send-email-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
On Wed, May 04, 2016 at 06:41:58PM +0300, Leon Romanovsky wrote:
> From: Mark Bloch <markb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
>
> There is an assumption that rdmacm is used only between nodes
> in the same IB subnet, this why ARP resolution can be used to turn
> IP to GID in rdmacm.
>
> When dealing with IB communication between subnets this assumption
> is no longer valid. ARP resolution will get us the next hop device
> address and not the peer node's device address.
>
> To overcome this limitation, let's check user space if it can
> provide the GID of the peer node, and fail if not.
>
> We add a sequence number to identify each request and fill in the GID
> upon answer from user space.
This description doesn't describe what this patch is trying to do.
This patch is delegating IP to GID translation to user space if there
is a route table entry for the destination.
I have to say, I really don't like this at all. If we want to have
proper routing support then the translation needs to be done somehow
in-band. What is user space supposed to do?
Jason
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next prev parent reply other threads:[~2016-05-04 18:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-04 15:41 [PATCH rdma-next 0/4] IB/core: Add InfiniBand router support Leon Romanovsky
[not found] ` <1462376518-6725-1-git-send-email-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-05-04 15:41 ` [PATCH rdma-next 1/4] IB/netlink: Make ib_netlink a standalone module Leon Romanovsky
[not found] ` <1462376518-6725-2-git-send-email-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-05-04 18:46 ` Jason Gunthorpe
[not found] ` <20160504184652.GC20554-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2016-05-04 20:53 ` Ira Weiny
[not found] ` <20160504205324.GA10115-f85VyEmKvEatqXYlAKuG4QC/G2K4zDHf@public.gmane.org>
2016-05-05 6:41 ` Leon Romanovsky
2016-05-04 15:41 ` [PATCH rdma-next 2/4] IB/netlink: Allow multiple clients to register under the same family Leon Romanovsky
[not found] ` <1462376518-6725-3-git-send-email-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-05-04 18:14 ` Dennis Dalessandro
2016-05-04 15:41 ` [PATCH rdma-next 3/4] IB/netlink: Add new local service operation Leon Romanovsky
2016-05-04 15:41 ` [PATCH rdma-next 4/4] IB/core: Add IP to GID netlink offload Leon Romanovsky
[not found] ` <1462376518-6725-5-git-send-email-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-05-04 18:52 ` Jason Gunthorpe [this message]
[not found] ` <20160504185241.GD20554-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2016-05-10 10:57 ` Mark Bloch
2016-05-04 21:32 ` Ira Weiny
[not found] ` <20160504213211.GB10115-f85VyEmKvEatqXYlAKuG4QC/G2K4zDHf@public.gmane.org>
2016-05-04 21:33 ` Jason Gunthorpe
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