On Mon, Jul 28, 2014 at 02:06:59PM +0100, David Vrabel wrote: > 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@xxxxxxxxxxxxxxx > > 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? We seem to trip over it frequently when rebooting a server. That is the VF's end up being unbinded while the guests are being shutdown. And depending on the timing we end up in a deadlock. > > > Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> > > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > > Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx> > > David -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html