From: "Pearson, Robert B" <robert.pearson2@hpe.com>
To: Jason Gunthorpe <jgg@nvidia.com>, Bob Pearson <rpearsonhpe@gmail.com>
Cc: Leon Romanovsky <leon@kernel.org>,
"zyjzyj2000@gmail.com" <zyjzyj2000@gmail.com>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"Zago, Frank" <frank.zago@hpe.com>
Subject: RE: [PATCH for-next] RDMA/rxe: Fix ib_device reference counting (again)
Date: Mon, 1 Mar 2021 18:20:06 +0000 [thread overview]
Message-ID: <CS1PR8401MB08218976C89D1C7B20394B4DBC9A9@CS1PR8401MB0821.NAMPRD84.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20210301173540.GN4247@nvidia.com>
> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Monday, March 1, 2021 11:36 AM
> To: Bob Pearson <rpearsonhpe@gmail.com>
> Cc: Leon Romanovsky <leon@kernel.org>; zyjzyj2000@gmail.com; linux-rdma@vger.kernel.org; Zago, Frank <frank.zago@hpe.com>
> Subject: Re: [PATCH for-next] RDMA/rxe: Fix ib_device reference counting (again)
> On Mon, Mar 01, 2021 at 10:54:21AM -0600, Bob Pearson wrote:
>> I agree that ib_device_get/put is attempting to solve a problem that
>> it not really very critical since ib_device is very unlikely to be
>> shut down in the middle of a data transfer. The driver never worried about this for years.
>> But now that it's been put on the table it should be done right. A
>> data packet arriving is completely independent of the verbs API which
>> *could* delete all the QPs and shut down the HCA while it was
>> wondering around the universe or worse yet while the packet is being processed.
> If driver shutdown can guarentee that all pointers involved in multicast are revoked before shutdown can finish then you don't need this
> refcounting.
> It was only brought up because the API that returns the ib_device from the netdev requires the refcounts as it is general purpose
> Jason
Unfortunately what you ask for is exactly what the refcounting code accomplishes and I don't see a simpler way to get there.
This also applies to the non-multicast packets as well but all the debate has been about the code in rxe_rcv_mcast_pkt()
because it is more blatant there or because I haven't been able to explain how it works well enough.
Bob
next prev parent reply other threads:[~2021-03-01 18:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-14 22:26 [PATCH for-next] RDMA/rxe: Fix ib_device reference counting (again) Bob Pearson
2021-02-15 3:46 ` Zhu Yanjun
2021-02-15 5:59 ` Leon Romanovsky
2021-02-26 23:28 ` Bob Pearson
2021-02-26 23:33 ` Jason Gunthorpe
2021-02-27 0:02 ` Bob Pearson
2021-02-27 8:43 ` Leon Romanovsky
2021-02-28 17:04 ` Bob Pearson
2021-03-01 7:24 ` Leon Romanovsky
2021-03-01 16:54 ` Bob Pearson
2021-03-01 17:35 ` Jason Gunthorpe
2021-03-01 18:20 ` Pearson, Robert B [this message]
2021-03-01 18:27 ` Jason Gunthorpe
2021-03-02 8:11 ` Leon Romanovsky
2021-03-01 7:42 ` Zhu Yanjun
2021-03-02 5:19 ` Zhu Yanjun
2021-03-02 7:26 ` Robert Pearson
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