From: Keith Busch <kbusch@kernel.org>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: Jens Axboe <axboe@fb.com>, Hannes Reinecke <hare@suse.com>,
Sagi Grimberg <sagi@grimberg.me>,
"Martin K . Petersen" <martin.petersen@oracle.com>,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
Keith Busch <keith.busch@intel.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] nvme-core: Fix subsystem instance mismatches
Date: Tue, 3 Sep 2019 10:46:20 -0600 [thread overview]
Message-ID: <20190903164620.GA20847@localhost.localdomain> (raw)
In-Reply-To: <33af4d94-9f6d-9baa-01fa-0f75ccee263e@deltatee.com>
On Tue, Sep 03, 2019 at 10:08:01AM -0600, Logan Gunthorpe wrote:
> On 2019-08-31 9:29 a.m., Keith Busch wrote:
> > On Fri, Aug 30, 2019 at 06:01:39PM -0600, Logan Gunthorpe wrote:
> >> To fix this, assign the subsystem's instance based on the instance
> >> number of the controller's instance that first created it. There should
> >> always be fewer subsystems than controllers so the should not be a need
> >> to create extra subsystems that overlap existing controllers.
> >
> > The subsystem's lifetime is not tied to the controller's. When the
> > controller is removed and releases its instance, the next controller
> > to take that available instance will create naming collisions with the
> > subsystem still using it.
> >
>
> Hmm, yes, ok.
>
> So perhaps we can just make the subsystem prefer the ctrl's instance
> when allocating the ID? Then at least, in the common case, the
> controller numbers will match the subsystem numbers. Only when there's
> random hot-plugs would the numbers get out of sync.
I really don't know about a patch that works only on static
configurations. Connects and disconnects do happen on live systems,
so the numerals will inevitably get out of sync.
Could we possibly make /dev/nvmeX be a subsystem handle without causing
trouble for anyone? This would essentially be the same thing as today
for non-CMIC controllers with a device-per-controller and only affects
the CMIC ones.
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next prev parent reply other threads:[~2019-09-03 16:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-31 0:01 [PATCH] nvme-core: Fix subsystem instance mismatches Logan Gunthorpe
2019-08-31 15:29 ` Keith Busch
2019-09-03 16:08 ` Logan Gunthorpe
2019-09-03 16:46 ` Keith Busch [this message]
2019-09-03 18:13 ` Logan Gunthorpe
2019-09-04 6:05 ` Christoph Hellwig
2019-09-04 14:44 ` Keith Busch
2019-09-04 15:42 ` Christoph Hellwig
2019-09-04 15:54 ` Keith Busch
2019-09-04 16:02 ` Christoph Hellwig
2019-09-04 16:07 ` Logan Gunthorpe
2019-09-04 16:35 ` Keith Busch
2019-09-04 17:01 ` Logan Gunthorpe
2019-09-04 17:14 ` Keith Busch
2019-09-04 17:29 ` Logan Gunthorpe
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