RE: [PATCH for-next V1 5/9] IB/core: Add rdma_network_type to wc

From: Liran Liss <liranl-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
To: Jason Gunthorpe
	<jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>,
	Matan Barak
	<matanb-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
Cc: Matan Barak <matanb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-rdma <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Or Gerlitz <ogerlitz-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Eran Ben Elisha <eranbe-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Somnath Kotur
	<Somnath.Kotur-1wcpHE2jlwO1Z/+hSey0Gg@public.gmane.org>
Subject: RE: [PATCH for-next V1 5/9] IB/core: Add rdma_network_type to wc
Date: Mon, 30 Nov 2015 20:56:15 +0000	[thread overview]
Message-ID: <HE1PR05MB1418F62E731D463F2A63A899B1000@HE1PR05MB1418.eurprd05.prod.outlook.com> (raw)
In-Reply-To: <20151124181415.GC10391-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>

> From: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org [mailto:linux-rdma-

> 
> The abstraction at the gid cache is making it too easy to make this mistake. It
> is enabling callers to do direct gid lookups without a route lookup, which is
> unconditionally wrong. Every call site into the gid cache I looked at appears to
> have this problem.
> 
> The simplest fix is to have a new gid cache api for rocve2 that somehow
> forces/includes the necessary route lookup. The existing API cannot simply
> be extended for rocev2.
> 

I think that the GID cache should remain just that: a cache.
We shouldn't bloat it.
The CMA is the proper place to handle IP resolution.

> > roce_gid_mgmt, is the part that populates this "dumb" database.
> > IMHO, adding such a "smart" layer to the GID cache is wrong, as this
> > should be part of RDMACM which does the translation. No need to get
> > the gid cache involved.
> 
> OK. Change the gid cache so only a RDMA CM private API can return
> rocev2 gids.
> 

The same cache is also used in IB and thus by other components, so it cannot
be a private CM API.
RoCE ULPs use the CMA for establishing connections, so route lookups should
be done from there.
 --Liran

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