From: Jiri Pirko <jiri@resnulli.us>
To: Leon Romanovsky <leon@kernel.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
Jakub Kicinski <kuba@kernel.org>, Jiri Pirko <jiri@nvidia.com>,
Ido Schimmel <idosch@idosch.org>,
"David S . Miller" <davem@davemloft.net>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
edwin.peer@broadcom.com
Subject: Re: [PATCH net-next] devlink: Require devlink lock during device reload
Date: Mon, 15 Nov 2021 12:20:21 +0100 [thread overview]
Message-ID: <YZJCdSy+wzqlwrE2@nanopsycho> (raw)
In-Reply-To: <YZCqVig9GQi/o1iz@unreal>
Sun, Nov 14, 2021 at 07:19:02AM CET, leon@kernel.org wrote:
>On Fri, Nov 12, 2021 at 08:38:56AM +0100, Jiri Pirko wrote:
>> Thu, Nov 11, 2021 at 01:17:52PM CET, leon@kernel.org wrote:
>> >On Thu, Nov 11, 2021 at 01:05:11PM +0100, Jiri Pirko wrote:
>> >> Tue, Nov 09, 2021 at 07:24:27PM CET, jgg@nvidia.com wrote:
>> >> >On Tue, Nov 09, 2021 at 08:20:42AM -0800, Jakub Kicinski wrote:
>> >> >> On Tue, 9 Nov 2021 11:33:35 -0400 Jason Gunthorpe wrote:
>> >> >> > > > I once sketched out fixing this by removing the need to hold the
>> >> >> > > > per_net_rwsem just for list iteration, which in turn avoids holding it
>> >> >> > > > over the devlink reload paths. It seemed like a reasonable step toward
>> >> >> > > > finer grained locking.
>> >> >> > >
>> >> >> > > Seems to me the locking is just a symptom.
>> >> >> >
>> >> >> > My fear is this reload during net ns destruction is devlink uAPI now
>> >> >> > and, yes it may be only a symptom, but the root cause may be unfixable
>> >> >> > uAPI constraints.
>> >> >>
>> >> >> If I'm reading this right it locks up 100% of the time, what is a uAPI
>> >> >> for? DoS? ;)
>> >> >>
>> >> >> Hence my questions about the actual use cases.
>> >> >
>> >> >Removing namespace support from devlink would solve the crasher. I
>> >> >certainly didn't feel bold enough to suggest such a thing :)
>> >> >
>> >> >If no other devlink driver cares about this it is probably the best
>> >> >idea.
>> >>
>> >> Devlink namespace support is not generic, not related to any driver.
>> >
>> >What do you mean?
>> >
>> >devlink_pernet_pre_exit() calls to devlink reload, which means that only
>> >drivers that support reload care about it. The reload is driver thing.
>>
>> However, Jason was talking about "namespace support removal from
>> devlink"..
>
>The code that sparkles deadlocks is in devlink_pernet_pre_exit() and
>this will be nice to remove. I just don't know if it is possible to do
>without ripping whole namespace support from devlink.
As discussed offline, the non-standard mlx5/IB usage of network
namespaces requires non standard mlx5/IB workaround. Does not make any
sense to remove the devlink net namespace support removal.
>
>Thanks
>
>>
>>
>> >
>> >Thanks
>> >
>> >>
>> >> >
>> >> >Jason
next prev parent reply other threads:[~2021-11-15 11:20 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-31 17:35 [PATCH net-next] devlink: Require devlink lock during device reload Leon Romanovsky
2021-11-01 7:12 ` Ido Schimmel
2021-11-01 15:03 ` Jiri Pirko
2021-11-01 20:52 ` Ido Schimmel
2021-11-01 23:11 ` Jakub Kicinski
2021-11-07 17:16 ` Ido Schimmel
2021-11-07 17:54 ` Leon Romanovsky
2021-11-08 16:09 ` Jakub Kicinski
2021-11-08 17:32 ` Leon Romanovsky
2021-11-08 18:16 ` Jakub Kicinski
2021-11-08 18:24 ` Leon Romanovsky
2021-11-08 18:46 ` Jakub Kicinski
2021-11-08 19:58 ` Leon Romanovsky
2021-11-08 23:31 ` Jakub Kicinski
2021-11-09 14:12 ` Leon Romanovsky
2021-11-09 14:17 ` Jakub Kicinski
2021-11-09 14:30 ` Leon Romanovsky
2021-11-09 14:49 ` Jakub Kicinski
2021-11-09 16:29 ` Jiri Pirko
2021-11-09 14:43 ` Jason Gunthorpe
2021-11-09 15:07 ` Jakub Kicinski
2021-11-09 15:33 ` Jason Gunthorpe
2021-11-09 16:20 ` Jakub Kicinski
2021-11-09 18:24 ` Jason Gunthorpe
2021-11-11 12:05 ` Jiri Pirko
2021-11-11 12:17 ` Leon Romanovsky
2021-11-12 7:38 ` Jiri Pirko
2021-11-14 6:19 ` Leon Romanovsky
2021-11-15 11:20 ` Jiri Pirko [this message]
2021-11-15 12:53 ` Jason Gunthorpe
2021-11-15 14:42 ` Jiri Pirko
2021-11-15 15:09 ` Jason Gunthorpe
2021-11-15 15:22 ` Jakub Kicinski
2021-11-16 7:00 ` Jiri Pirko
2021-11-16 13:45 ` Jakub Kicinski
2021-11-16 6:57 ` Jiri Pirko
2021-11-16 12:44 ` Jason Gunthorpe
2021-11-17 14:15 ` Leon Romanovsky
2021-11-10 7:52 ` Leon Romanovsky
2021-11-09 16:15 ` Jiri Pirko
2021-11-09 16:26 ` Jakub Kicinski
2021-11-09 16:30 ` Jiri Pirko
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