[lkml]   [2015]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH] x86/PCI: Fully disable devices before releasing IRQ resource
The IRQ resource for a device is established when pci_enabled_device()
is called on a fully disabled device (ie. enable_cnt == 0). With
commit b4b55cda5874 ("x86/PCI: Refine the way to release PCI IRQ
resources") this same IRQ resource is released when the driver is
unbound from the device, regardless of the enable_cnt. This presents
the situation that an ill-behaved driver can now make a device
unusable to subsequent drivers by an imbalance in their use of
pci_enable/disable_device(). It's one thing to break your own device
if you're one of these ill-behaved drivers, but it's a serious
regression for secondary drivers like vfio-pci, which are innocent
of the transgressions of the previous driver.

Resolve by pushing the device to a fully disabled state before
releasing the IRQ resource.

Fixes: b4b55cda5874 ("x86/PCI: Refine the way to release PCI IRQ resources")
Signed-off-by: Alex Williamson <>
Cc: Jiang Liu <>
arch/x86/pci/common.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 3d2612b..4810194 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -527,8 +527,19 @@ static int pci_irq_notifier(struct notifier_block *nb, unsigned long action,

- if (pcibios_disable_irq)
+ if (pcibios_disable_irq) {
+ /*
+ * Broken drivers may allow a device to be .remove()'d while
+ * still enabled. pci_enable_device() will only re-establish
+ * dev->irq if the devices is fully disabled. So if we want
+ * to release the IRQ, we need to make sure the next driver
+ * can re-establish it using pci_enable_device().
+ */
+ while (pci_is_enabled(dev))
+ pci_disable_device(dev);
+ }

return NOTIFY_OK;

 \ /
  Last update: 2015-03-05 22:21    [W:0.186 / U:0.048 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site