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| author |   Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2014-12-03 16:40:26 -0500 |
|---|---|---|
| committer |   David Vrabel <david.vrabel@citrix.com> | 2014-12-04 12:41:58 +0000 |
| commit | e8801a7418dda995a70f30874aef77e6d064828e (patch) | |
| tree | ee4e691009b468c5397216b9e5776c6c239cc51e /drivers/xen/xen-pciback/passthrough.c | |
| parent | swiotlb-xen: pass dev_addr to swiotlb_tbl_unmap_single (diff) | |
| download | linux-dev-e8801a7418dda995a70f30874aef77e6d064828e.tar.xz linux-dev-e8801a7418dda995a70f30874aef77e6d064828e.zip | |
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 <boris.ostrovsky@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Diffstat (limited to 'drivers/xen/xen-pciback/passthrough.c')
| -rw-r--r-- | drivers/xen/xen-pciback/passthrough.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/xen/xen-pciback/passthrough.c b/drivers/xen/xen-pciback/passthrough.c index 828dddc360df..f16a30e2a110 100644 --- a/drivers/xen/xen-pciback/passthrough.c +++ b/drivers/xen/xen-pciback/passthrough.c @@ -69,7 +69,7 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev, } static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev, - struct pci_dev *dev) + struct pci_dev *dev, bool lock) { struct passthrough_dev_data *dev_data = pdev->pci_dev_data; struct pci_dev_entry *dev_entry, *t; @@ -87,8 +87,13 @@ static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev, mutex_unlock(&dev_data->lock); - if (found_dev) + if (found_dev) { + if (lock) + device_lock(&found_dev->dev); pcistub_put_pci_dev(found_dev); + if (lock) + device_unlock(&found_dev->dev); + } } static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev) @@ -156,8 +161,11 @@ static void __xen_pcibk_release_devices(struct xen_pcibk_device *pdev) struct pci_dev_entry *dev_entry, *t; list_for_each_entry_safe(dev_entry, t, &dev_data->dev_list, list) { + struct pci_dev *dev = dev_entry->dev; list_del(&dev_entry->list); - pcistub_put_pci_dev(dev_entry->dev); + device_lock(&dev->dev); + pcistub_put_pci_dev(dev); + device_unlock(&dev->dev); kfree(dev_entry); } |