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From:   Rajat Jain <rajatja@google.com>
Date:   Thu, 29 Apr 2021 09:59:39 -0700
Message-ID: <CACK8Z6E_zbUguY2qUE5Jbgzj3fwcQ_xMVxHYs_VeY5Hm=S4zGQ@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] pci: Support "removable" attribute for PCI devices
To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     Oliver Neukum <oneukum@suse.com>,
        David Laight <David.Laight@aculab.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux PCI <linux-pci@vger.kernel.org>,
        "open list:ULTRA-WIDEBAND (UWB) SUBSYSTEM:" 
        <linux-usb@vger.kernel.org>, Bjorn Helgaas <helgaas@kernel.org>,
        Rajat Jain <rajatxjain@gmail.com>,
        Jesse Barnes <jsbarnes@google.com>,
        Dmitry Torokhov <dtor@google.com>
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On Thu, Apr 29, 2021 at 2:58 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Thu, Apr 29, 2021 at 11:03 AM Oliver Neukum <oneukum@suse.com> wrote:
> >
> > Am Mittwoch, den 28.04.2021, 14:21 +0200 schrieb Rafael J. Wysocki:
> >
> > > In principle, in the wake of Thunderbolt every PCI driver handling
> > > PCIe devices needs to be able to deal with a device that's gone away
> > > without notice, because in principle any PCIe device can be included
> > > into a Thunderbolt docking station which may go away as a whole
> > > without notice.
> >
> > Yes, but we are dealing with what we export to user space, don't we?
>
> Right, so it would be good to know why exporting this information to
> user space is desired.

For us, the driving motivation is to implement policies in userspace
for user removable devices. Eg:

* Tracking the statistics around usage of user removable devices (how
many users use such devices, how often etc).
* Removing user removable devices when a user logs out.
* Not allowing a new user removable device while the screen is locked.
* (perhaps additional such policies in future).

Thanks,

Rajat