linux-kernel - Re: [PATCH blktests v1 2/3] nvme/rc: Avoid triggering host nvme-cli autoconnect

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Message-ID: <39f9977e-b34c-f2dd-d356-8c78414a60d1@nvidia.com>
Date:   Mon, 10 Jul 2023 12:53:17 +0300
From:   Max Gurtovoy <mgurtovoy@...dia.com>
To:     Daniel Wagner <dwagner@...e.de>
Cc:     linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, Chaitanya Kulkarni <kch@...dia.com>,
        Shin'ichiro Kawasaki <shinichiro@...tmail.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Hannes Reinecke <hare@...e.de>,
        James Smart <jsmart2021@...il.com>,
        Martin Belanger <Martin.Belanger@...l.com>
Subject: Re: [PATCH blktests v1 2/3] nvme/rc: Avoid triggering host nvme-cli
 autoconnect



On 10/07/2023 11:27, Daniel Wagner wrote:
> On Thu, Jul 06, 2023 at 07:11:58PM +0300, Max Gurtovoy wrote:
>>
>>
>> On 20/06/2023 16:27, Daniel Wagner wrote:
>>> When the host has enabled the udev/systemd autoconnect services for the
>>> fc transport it interacts with blktests and make tests break.
>>>
>>> nvme-cli learned to ignore connects attemps when using the
>>> --context command line option paired with a volatile configuration. Thus
>>> we can mark all the resources created by blktests and avoid any
>>> interaction with the systemd autoconnect scripts.
>>
>> why would we like to ignore connect attempts during blktests ?
> 
> The problem I observed is that there were two connect attempts (one triggered
> via udev and one via the test itself) which disturbed the test. The interference
> resulted into a complete hang of the test case:
> 
> https://lore.kernel.org/linux-nvme/6g53yj5afhhonwf2psf7ft2gkakkwewy7klkix3y3u6uclpa5w@tt2yfzigyxgg/
> 
>> We define unique nqn/ids/etc. So we never should disturb other running
>> services, unless it uses the same parameters, which shouldn't happen.
> 
> Yes, that should do the decoupling between udev and blktests.
> 
>> Agree on setting the hard coded values for hostnqn and hostid instead of
>> reading the /etc/nvme/* files. This should do the work IMO, isn't it ?
> 
> Do you mean that nvme-cli will ignore the udev trigger when a different hostnqn
> is invovled? At least for the well-known discover controller the hostqnq
> doesn't work. Though not sure if I understood you correctly here.

All I was saying is that your issue would have been fixed easily by 2-3 
LOC by removing the usage of /etc/nvme/* files that are usually 
configured by system administrator and use a default values for blktests 
hostnqn and hostid.
The usage of --context in blktests is redundant IMO.