From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Keith Busch <keith.busch@intel.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,
Jens Axboe <axboe@fb.com>, Logan Gunthorpe <logang@deltatee.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] nvme-core: Fix subsystem instance mismatches
Date: Wed, 4 Sep 2019 17:42:15 +0200 [thread overview]
Message-ID: <20190904154215.GA20422@lst.de> (raw)
In-Reply-To: <20190904144426.GB21302@localhost.localdomain>
On Wed, Sep 04, 2019 at 08:44:27AM -0600, Keith Busch wrote:
> Let me step through an example:
>
> Ctrl A gets instance 0.
>
> Its subsystem gets the same instance, and takes ref count on it:
> all namespaces in this subsystem will use '0'.
>
> Ctrl B gets instance 1, and it's in the same subsystem as Ctrl A so
> no new subsytem is allocated.
>
> Ctrl A is disconnected, dropping its ref on instance 0, but the
> subsystem still has its refcount, making it unavailable.
>
> Ctrl A is reconnected, and allocates instance 2 because 0 is still in
> use.
>
> Now all the namespaces in this subsystem are prefixed with nvme0, but no
> controller exists with the same prefix. We still have inevitable naming
> mismatch, right?
I think th major confusion was that we can use the same handle for
and unrelated subsystem vs controller, and that would avoid it.
I don't see how we can avoid the controller is entirely different
from namespace problem ever.
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next prev parent reply other threads:[~2019-09-04 15:42 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
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 [this message]
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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