From: Chris Lalancette <clalance@redhat.com>
Date: Wed, 28 Jul 2010 18:07:08 +0000 (-0400)
Subject: Fix a potential race in pciInitDevice.
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=56b408231a913f07d81e4a9c24f907efdae7dbf5;p=libvirt.git

Fix a potential race in pciInitDevice.

If detecting the FLR flag of a pci device fails, then we
could run into the situation of trying to close a file
descriptor twice, once in pciInitDevice() and once in pciFreeDevice().
Fix that by removing the pciCloseConfig() in pciInitDevice() and
just letting pciFreeDevice() handle it.

Thanks to Chris Wright for pointing out this problem.

While we are at it, fix an error check.  While it would actually
work as-is (since success returns 0), it's still more clear to
check for < 0 (as the rest of the code does).

Signed-off-by: Chris Lalancette <clalance@redhat.com>
---

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 767265d7a5..098f4daec0 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -8018,7 +8018,7 @@ static int qemudDomainAttachHostPciDevice(struct qemud_driver *driver,
         return -1;
     }
 
-    if (qemuPrepareHostdevPCIDevices(driver, &hostdev, 1))
+    if (qemuPrepareHostdevPCIDevices(driver, &hostdev, 1) < 0)
         return -1;
 
     if (qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE) {
diff --git a/src/util/pci.c b/src/util/pci.c
index 02d88df55f..53f9ded02f 100644
--- a/src/util/pci.c
+++ b/src/util/pci.c
@@ -188,8 +188,10 @@ pciCloseConfig(pciDevice *dev)
     if (!dev)
         return;
 
-    if (dev->fd >= 0)
+    if (dev->fd >= 0) {
         close(dev->fd);
+        dev->fd = -1;
+    }
 }
 
 static int
@@ -672,10 +674,8 @@ pciInitDevice(pciDevice *dev)
     dev->pcie_cap_pos   = pciFindCapabilityOffset(dev, PCI_CAP_ID_EXP);
     dev->pci_pm_cap_pos = pciFindCapabilityOffset(dev, PCI_CAP_ID_PM);
     flr = pciDetectFunctionLevelReset(dev);
-    if (flr < 0) {
-        pciCloseConfig(dev);
+    if (flr < 0)
         return flr;
-    }
     dev->has_flr        = flr;
     dev->has_pm_reset   = pciDetectPowerManagementReset(dev);
     dev->initted        = 1;