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Date: Thu, 8 Mar 2012 07:45:25 -0800
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: Yinghai Lu <yinghai@kernel.org>, Jesse Barnes <jbarnes@virtuousgeek.org>,
        x86 <x86@kernel.org>, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org, Randy Dunlap <rdunlap@xenotime.net>,
        linux-doc@vger.kernel.org, Matthew Garrett <mjg@redhat.com>,
        linux-acpi@vger.kernel.org
Subject: Re: [PATCH 16/23] PCI: add pci bus removal through
 /sys/.../pci_bus/.../remove
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On Wed, Mar 07, 2012 at 09:45:18PM -0700, Bjorn Helgaas wrote:
> >> I'm not sure it makes sense to talk about removing a "bus" and leaving
> >> the upstream bridge (either a host bridge or a P2P bridge).  I think
> >> it'd make more sense to remove the bridge itself, which would of
> >> course have the consequence of removing the secondary bus.
> >
> > for root bus, that remove pci_host_bridge and pci root bus.
> >
> > for pci bus under pci bridge, will remove that pci bus, but will still
> > keep  that pci bridge.
> > that should be ok. just like some pci bridge is there, and later can
> > not create child bus for it.
> >
> > there is one case: during test busn_alloc, i need to remove all device
> > on one bus, and
> > use setpci to change bridge bus number register. then use rescan
> > bridge to create new bus.
> >
> > with this one, I just need to remove that bus, instead of remove
> > children devices one by one.
> 
> I don't think making it convenient for manual testing is an argument
> for this interface.  For sysfs interfaces it is more important to make
> something that fits well into the grand plan of how things Should
> Work.  If you need internal helper functions for convenience, I'm OK
> with that, because it's easier to change those than to change sysfs
> interfaces.

If it's "only" for testing, then put it in debugfs, not sysfs.

thanks,

greg k-h