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

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Date:   Mon, 10 Jul 2023 10:27:17 +0200
From:   Daniel Wagner <dwagner@...e.de>
To:     Max Gurtovoy <mgurtovoy@...dia.com>
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 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.