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From: Jason Gunthorpe <jgg@nvidia.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Leon Romanovsky <leon@kernel.org>,
	Bart Van Assche <bvanassche@acm.org>,
	Doug Ledford <dledford@redhat.com>,
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	Zhu Yanjun <zyjzyj2000@gmail.com>
Subject: Re: [PATCH rdma-next 01/10] RDMA: Add access flags to ib_alloc_mr() and ib_mr_pool_init()
Date: Tue, 6 Apr 2021 11:04:37 -0300
Message-ID: <20210406140437.GR7405@nvidia.com> (raw)
In-Reply-To: <20210406123034.GA28930@lst.de>

On Tue, Apr 06, 2021 at 02:30:34PM +0200, Christoph Hellwig wrote:
> On Tue, Apr 06, 2021 at 09:13:12AM -0300, Jason Gunthorpe wrote:
> > So we broadly have two choice
> >  1) Diverge the kernel and user interfaces and make the RDMA drivers
> >     special case all the kernel stuff to force
> >     ACCESS_RELAXED_ORDERING when they are building MRs and processing
> >     FMR WQE's
> >  2) Keep the two interfaces the same and push the
> >     ACCESS_RELAXED_ORDERING to a couple of places in the ULPs so the
> >     drivers see a consistent API
> > 
> > They are both poor choices, but I think #2 has a greater chance of
> > everyone doing their parts correctly.
> 
> No, 1 is the only sensible choice.  The userspace verbs interface is
> a mess and should not inflict pain on the kernel in any way.  We've moved
> away from a lot of the idiotic "Verbs API" concepts with things like
> how we handle the global lkey, the new CQ API and the RDMA R/W
> abstraction and that massively helped the kernel ecosystem.

It might be idiodic, but I have to keep the uverbs thing working
too.

There is a lot of assumption baked in to all the drivers that
user/kernel is the same thing, we'd have to go in and break this.

Essentially #2 ends up as deleting IB_ACCESS_RELAXED_ORDERING kernel
side and instead doing some IB_ACCESS_DISABLE_RO in kernel,
translating uverbs IBV_ACCESS_* to this then finding and inverting all
the driver logic and also finding and unblocking all the places that
enforce valid access flags in the drivers. It is complicated enough

Maybe Avihai will give it a try

Jason

  reply index

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-05  5:23 [PATCH rdma-next 00/10] Enable relaxed ordering for ULPs Leon Romanovsky
2021-04-05  5:23 ` [PATCH rdma-next 01/10] RDMA: Add access flags to ib_alloc_mr() and ib_mr_pool_init() Leon Romanovsky
2021-04-05 13:46   ` Christoph Hellwig
2021-04-06  5:24     ` Leon Romanovsky
2021-04-05 15:27   ` Bart Van Assche
2021-04-06  5:23     ` Leon Romanovsky
2021-04-06  5:27       ` Christoph Hellwig
2021-04-06  5:58         ` Leon Romanovsky
2021-04-06 12:13           ` Jason Gunthorpe
2021-04-06 12:30             ` Christoph Hellwig
2021-04-06 14:04               ` Jason Gunthorpe [this message]
2021-04-06 14:15                 ` Christoph Hellwig
2021-04-06 14:40                   ` Jason Gunthorpe
2021-04-06 14:54                     ` Christoph Hellwig
2021-04-06 15:03                       ` Christoph Hellwig
2021-04-07 18:28                       ` Jason Gunthorpe
2021-04-05  5:23 ` [PATCH rdma-next 02/10] RDMA/core: Enable Relaxed Ordering in __ib_alloc_pd() Leon Romanovsky
2021-04-05 18:01   ` Tom Talpey
2021-04-05 20:40     ` Adit Ranadive
2021-04-06  6:28     ` Leon Romanovsky
2021-04-05  5:23 ` [PATCH rdma-next 03/10] RDMA/iser: Enable Relaxed Ordering Leon Romanovsky
2021-04-05  5:23 ` [PATCH rdma-next 04/10] RDMA/rtrs: " Leon Romanovsky
2021-04-05  5:23 ` [PATCH rdma-next 05/10] RDMA/srp: " Leon Romanovsky
2021-04-05  5:24 ` [PATCH rdma-next 06/10] nvme-rdma: " Leon Romanovsky
2021-04-05  5:24 ` [PATCH rdma-next 07/10] cifs: smbd: " Leon Romanovsky
2021-04-05  5:24 ` [PATCH rdma-next 08/10] net/rds: " Leon Romanovsky
2021-04-05  5:24 ` [PATCH rdma-next 09/10] net/smc: " Leon Romanovsky
2021-04-05  5:24 ` [PATCH rdma-next 10/10] xprtrdma: " Leon Romanovsky
2021-04-05 13:41 ` [PATCH rdma-next 00/10] Enable relaxed ordering for ULPs Christoph Hellwig
2021-04-05 14:08   ` Leon Romanovsky
2021-04-05 16:11     ` Santosh Shilimkar
2021-04-05 17:54     ` Tom Talpey
2021-04-05 20:07   ` Jason Gunthorpe
2021-04-05 23:42     ` Chuck Lever III
2021-04-05 23:50       ` Keith Busch
2021-04-06  5:12       ` Leon Romanovsky
2021-04-06 11:49       ` Jason Gunthorpe
2021-04-09 14:26         ` Tom Talpey
2021-04-09 14:45           ` Chuck Lever III
2021-04-09 15:32             ` Tom Talpey
2021-04-09 16:27               ` Haakon Bugge
2021-04-09 17:49                 ` Tom Talpey
2021-04-10 13:30                   ` David Laight
2021-04-12 18:32                     ` Haakon Bugge
2021-04-12 20:20                       ` Tom Talpey
2021-04-12 22:48                         ` Jason Gunthorpe
2021-04-14 14:16                           ` Tom Talpey
2021-04-14 14:41                             ` David Laight
2021-04-14 14:49                               ` Jason Gunthorpe
2021-04-14 14:44                             ` Jason Gunthorpe
2021-04-09 16:40           ` Jason Gunthorpe
2021-04-09 17:44             ` Tom Talpey
2021-04-06  2:37 ` Honggang LI
2021-04-06  5:09   ` Leon Romanovsky
2021-04-06 11:53     ` Jason Gunthorpe
2021-04-11 10:09       ` Max Gurtovoy

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