PCI: Introduce INTx check & mask API

These new PCI services allow to probe for 2.3-compliant INTx masking
support and then use the feature from PCI interrupt handlers. The
services are properly synchronized with concurrent config space access
via sysfs or on device reset.

This enables generic PCI device drivers like uio_pci_generic or KVM's
device assignment to implement the necessary kernel-side IRQ handling
without any knowledge about device-specific interrupt status and control
registers.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index b74084e9ca12..3b6e4ed306b6 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -136,6 +136,8 @@ static inline void pci_remove_legacy_files(struct pci_bus *bus) { return; }
 /* Lock for read/write access to pci device and bus lists */
 extern struct rw_semaphore pci_bus_sem;
 
+extern raw_spinlock_t pci_lock;
+
 extern unsigned int pci_pm_d3_delay;
 
 #ifdef CONFIG_PCI_MSI