From e8801a7418dda995a70f30874aef77e6d064828e Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Wed, 3 Dec 2014 16:40:26 -0500 Subject: xen/pciback: Don't deadlock when unbinding. 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. Reviewed-by: Boris Ostrovsky Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: David Vrabel --- drivers/xen/xen-pciback/xenbus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/xen/xen-pciback/xenbus.c') diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c index ad8d30c088fe..eeee499d4b3c 100644 --- a/drivers/xen/xen-pciback/xenbus.c +++ b/drivers/xen/xen-pciback/xenbus.c @@ -291,7 +291,7 @@ static int xen_pcibk_remove_device(struct xen_pcibk_device *pdev, /* N.B. This ends up calling pcistub_put_pci_dev which ends up * doing the FLR. */ - xen_pcibk_release_pci_dev(pdev, dev); + xen_pcibk_release_pci_dev(pdev, dev, true /* use the lock. */); out: return err; -- cgit v1.2.3-59-g8ed1b