From: Guenter Roeck <linux@roeck-us.net>
To: Hannes Reinecke <hare@suse.de>
Cc: linux-nvme@lists.infradead.org, Daniel Wagner <dwagner@suse.de>,
Christoph Hellwig <hch@lst.de>, Keith Busch <keith.busch@wdc.com>,
Sagi Grimberg <sagi@grimberg.me>
Subject: Re: [PATCHv2] nvme/hwmon: rework to avoid devm allocation
Date: Tue, 19 Jan 2021 21:54:30 -0800 [thread overview]
Message-ID: <efddf566-a5a1-cda0-5fec-5e8a1d6bffb3@roeck-us.net> (raw)
In-Reply-To: <1093bedb-9b6d-b365-85d0-de8ef7eceb95@suse.de>
On 1/19/21 11:07 AM, Hannes Reinecke wrote:
> On 1/19/21 3:56 PM, Guenter Roeck wrote:
>> On Tue, Jan 19, 2021 at 07:43:18AM +0100, Hannes Reinecke wrote:
>>> The original design to use device-managed resource allocation
>>> doesn't really work as the NVMe controller has a vastly different
>>> lifetime than the hwmon sysfs attributes, causing warning about
>>> duplicate sysfs entries upon reconnection.
>>> This patch reworks the hwmon allocation to avoid device-managed
>>> resource allocation, and uses the NVMe controller as parent for
>>> the sysfs attributes.
>>
>> I don't really know enough about the nvme infrastructure to understand
>> this part of the change. Couple of questions: Why is the parent change
>> needed, and does the "sensors" command still work after this change ?
>>
> Problem is that it's not really a 'new' infrastructure, it's NVMe-over-fabrics, which behaves slightly different from the PCI-based NVMe devices.
> In particular we can and will have connectivity failures, requiring the controller to be reset or recreated.
> And as the hwmon sysfs attributes were never removed correctly in the first place we're seeing these errors.
> It isn't easily recreated on PCI devices as the sysfs attributes will only ever be removed on shutdown (or module unload).
> So I fear the issue was with us since day-1.
>
I understand; that is why I suggested to add a Fixes: tag.
> As for the parent change: for fabrics the '->dev' device points to a static nvmf_device, which is identical for every fabrics controller.
> So you really need to use the actual device in '->device' to have a different parent device for different controllers.
> So for PCI that means that the 'hwmon' device moved one element down (from the PCI device to the nvme controller).
> But shouldn't make much of a difference; I'll check on if 'sensors' continues to work.
>
It needs lm-sensors version 3.5.0 or later. Older versions
don't support a device hierarchy.
Guenter
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next prev parent reply other threads:[~2021-01-20 5:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-19 6:43 [PATCHv2] nvme/hwmon: rework to avoid devm allocation Hannes Reinecke
2021-01-19 8:03 ` Daniel Wagner
2021-01-19 14:56 ` Guenter Roeck
2021-01-19 19:07 ` Hannes Reinecke
2021-01-20 5:54 ` Guenter Roeck [this message]
2021-01-27 16:35 ` Christoph Hellwig
2021-02-09 12:37 ` Daniel Wagner
2021-01-19 22:18 ` Enzo Matsumiya
2021-02-10 8:11 ` Christoph Hellwig
2021-02-10 12:10 ` Minwoo Im
2021-02-10 13:11 ` Christoph Hellwig
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