Messages in this thread | | | Date | Mon, 28 Jul 2014 14:06:59 +0100 | From | David Vrabel <> | Subject | Re: [PATCH v5 2/6] xen/pciback: Don't deadlock when unbinding. |
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On 14/07/14 17:18, Konrad Rzeszutek Wilk wrote: > As commit 0a9fd0152929db372ff61b0d6c280fdd34ae8bdb > 'xen/pciback: Document the entry points for 'pcistub_put_pci_dev'' > explained there are four entry points in this function. > Two of them are when the user fiddles in the SysFS to > unbind a device which might be in use by a guest or not. > > Both 'unbind' states will cause a deadlock as the the PCI lock has > already been taken, which then pci_device_reset tries to take. > > We can simplify this by requiring that all callers of > pcistub_put_pci_dev MUST hold the device lock. And then > we can just call the lockless version of pci_device_reset. > > To make it even simpler we will modify xen_pcibk_release_pci_dev > to quality whether it should take a lock or not - as it ends > up calling xen_pcibk_release_pci_dev and needs to hold the lock. > > CC: stable@vger.kernel.org
This deadlock is for a rather specific and uncommon use case (manually unbinding a PCI while it is passed-through). Is this critical enough to warrant a stable backport?
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
David
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