[PATCH] xen: reuse the same pirq allocated when driver load first time

[Zhenzhong Duan <zhenzhong.duan@oracle.com>]

When driver load and unload in a loop, pirq will exhaust finally.
Try to use the same pirq which was already mapped and binded at first time
when driver loaded.

Read pirq from msix entry and test if data is XEN_PIRQ_MSI_DATA
xen_irq_from_pirq(pirq) < 0 checking is wrong as irq will be freed
when driver unload, it's always true in second load.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Tested-by: Yuval Shaia <yuval.shaia@oracle.com>
---
 arch/x86/pci/xen.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 94e7662..4289eef 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -230,8 +230,7 @@ static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 		__read_msi_msg(msidesc, &msg);
 		pirq = MSI_ADDR_EXT_DEST_ID(msg.address_hi) |
 			((msg.address_lo >> MSI_ADDR_DEST_ID_SHIFT) & 0xff);
-		if (msg.data != XEN_PIRQ_MSI_DATA ||
-		    xen_irq_from_pirq(pirq) < 0) {
+		if (msg.data != XEN_PIRQ_MSI_DATA) {
 			pirq = xen_allocate_pirq_msi(dev, msidesc);
 			if (pirq < 0) {
 				irq = -ENODEV;
-- 
1.7.3