Re: [PATCH -v3 40/47] PCI: Add pci bus removal through /sys/.../pci_bus/.../remove

[Bjorn Helgaas <bhelgaas@xxxxxxxxxx>]

On Fri, Apr 6, 2012 at 10:01 AM, Yinghai Lu <yhlu.kernel@xxxxxxxxx> wrote:
> On Fri, Apr 6, 2012 at 8:50 AM, Jiang Liu <liuj97@xxxxxxxxx> wrote:
>> Hi Yinghai,
>>        I found many other drivers assume that a pci bus won't disappear if
>> the corresponding PCI bridge device still exists. The sysfs interface proposed
>> here breaks that assumption and may cause many access-after-free issues.
>> So what's the purpose of this interface? Should we remove this interface or
>> enhance other drivers to avoid invalid memory access issues?

Can you point out some of the specifics about drivers making this
assumption?  I'm not thrilled about the idea of removing a pci_bus
while the upstream bridge pci_dev still exists either.

> ok, will make it only show up on root bus.

OK.  I'm still interested in the specifics because I don't like the
way the pci_bus is exposed, even inside the kernel.  The bus itself is
not an active entity, and we can't really do anything with it except
by touching a device connected to it.

Bjorn
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