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From: Jason Gunthorpe <jgg@nvidia.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Jiri Pirko <jiri@nvidia.com>, Leon Romanovsky <leon@kernel.org>,
	Ido Schimmel <idosch@idosch.org>, Jiri Pirko <jiri@resnulli.us>,
	"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: Tue, 9 Nov 2021 14:24:27 -0400	[thread overview]
Message-ID: <20211109182427.GJ1740502@nvidia.com> (raw)
In-Reply-To: <20211109082042.31cf29c3@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>

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.

Jason

  reply	other threads:[~2021-11-09 18:24 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 [this message]
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
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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