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[libvirt] [PATCH 22/24] hostdev: Streamline device ownership tracking



After this patch, ownership of virPCIDevice instances is very easy
to keep track of: for each host PCI device, the only instance that
actually matters is the one inside one of the bookkeeping list.

Whenever some operation needs to be performed on a PCI device, the
actual device is looked up first; when this is not the case, a
comment explains the reason.
---
 src/util/virhostdev.c | 118 +++++++++++++++++++++++++++-----------------------
 1 file changed, 65 insertions(+), 53 deletions(-)

diff --git a/src/util/virhostdev.c b/src/util/virhostdev.c
index d1529c5..b2f54cd 100644
--- a/src/util/virhostdev.c
+++ b/src/util/virhostdev.c
@@ -618,28 +618,22 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr mgr,
          last_processed_hostdev_vf = i;
     }
 
-    /* Step 5: Now mark all the devices as active */
+    /* Step 5: Move devices from the inactive list to the active list */
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr pci = virPCIDeviceListGet(pcidevs, i);
+        virPCIDevicePtr actual;
 
-        VIR_DEBUG("Adding PCI device %s to active list",
+        VIR_DEBUG("Removing PCI device %s from inactive list",
                   virPCIDeviceGetName(pci));
-        if (virPCIDeviceListAdd(mgr->activePCIHostdevs, pci) < 0)
-            goto inactivedevs;
-    }
-
-    /* Step 6: Now remove the devices from inactive list. */
-    for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
-        virPCIDevicePtr pci = virPCIDeviceListGet(pcidevs, i);
+        actual = virPCIDeviceListSteal(mgr->inactivePCIHostdevs, pci);
 
-        VIR_DEBUG("Removing PCI device %s from inactive list",
+        VIR_DEBUG("Adding PCI device %s to active list",
                   virPCIDeviceGetName(pci));
-        virPCIDeviceListDel(mgr->inactivePCIHostdevs, pci);
+        if (!actual || virPCIDeviceListAdd(mgr->activePCIHostdevs, actual) < 0)
+            goto inactivedevs;
     }
 
-    /* Step 7: Now set the used_by_domain of the device in
-     * activePCIHostdevs as domain name.
-     */
+    /* Step 6: Set driver and domain information */
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr pci, actual;
 
@@ -655,7 +649,7 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr mgr,
             virPCIDeviceSetUsedBy(actual, drv_name, dom_name);
     }
 
-    /* Step 8: Now set the original states for hostdev def */
+    /* Step 7: Now set the original states for hostdev def */
     for (i = 0; i < nhostdevs; i++) {
         virPCIDevicePtr actual;
         virDomainHostdevDefPtr hostdev = hostdevs[i];
@@ -690,23 +684,25 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr mgr,
         }
     }
 
-    /* Step 9: Now steal all the devices from pcidevs */
-    while (virPCIDeviceListCount(pcidevs) > 0)
-        virPCIDeviceListStealIndex(pcidevs, 0);
-
     ret = 0;
     goto cleanup;
 
  inactivedevs:
-    /* Only steal all the devices from activePCIHostdevs. We will
-     * free them in virObjectUnref().
-     */
+    /* Move devices back to the inactive list so that they can be
+     * processed properly below (reattachdevs label) */
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr pci = virPCIDeviceListGet(pcidevs, i);
+        virPCIDevicePtr actual;
 
         VIR_DEBUG("Removing PCI device %s from active list",
                   virPCIDeviceGetName(pci));
-        virPCIDeviceListSteal(mgr->activePCIHostdevs, pci);
+        if (!(actual = virPCIDeviceListSteal(mgr->activePCIHostdevs, pci)))
+            continue;
+
+        VIR_DEBUG("Adding PCI device %s to inactive list",
+                  virPCIDeviceGetName(pci));
+        if (virPCIDeviceListAdd(mgr->inactivePCIHostdevs, actual) < 0)
+            continue;
     }
 
  resetvfnetconfig:
@@ -716,16 +712,22 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr mgr,
  reattachdevs:
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr pci = virPCIDeviceListGet(pcidevs, i);
+        virPCIDevicePtr actual;
 
-        if (virPCIDeviceGetManaged(pci)) {
+        /* We need to look up the actual device because that's what
+         * virPCIDeviceReattach() exepects as its argument */
+        if (!(actual = virPCIDeviceListFind(mgr->inactivePCIHostdevs, pci)))
+            continue;
+
+        if (virPCIDeviceGetManaged(actual)) {
             VIR_DEBUG("Reattaching managed PCI device %s",
-                      virPCIDeviceGetName(pci));
-            ignore_value(virPCIDeviceReattach(pci,
+                      virPCIDeviceGetName(actual));
+            ignore_value(virPCIDeviceReattach(actual,
                                               mgr->activePCIHostdevs,
                                               mgr->inactivePCIHostdevs));
         } else {
             VIR_DEBUG("Not reattaching unmanaged PCI device %s",
-                      virPCIDeviceGetName(pci));
+                      virPCIDeviceGetName(actual));
         }
     }
 
@@ -745,17 +747,6 @@ static void
 virHostdevReattachPCIDevice(virHostdevManagerPtr mgr,
                             virPCIDevicePtr actual)
 {
-    /* If the device is not managed and was attached to guest
-     * successfully, it must have been inactive.
-     */
-    if (!virPCIDeviceGetManaged(actual)) {
-        VIR_DEBUG("Adding unmanaged PCI device %s to inactive list",
-                  virPCIDeviceGetName(actual));
-        if (virPCIDeviceListAdd(mgr->inactivePCIHostdevs, actual) < 0)
-            virPCIDeviceFree(actual);
-        return;
-    }
-
     /* Wait for device cleanup if it is qemu/kvm */
     if (virPCIDeviceGetStubDriver(actual) == VIR_PCI_STUB_DRIVER_KVM) {
         int retries = 100;
@@ -774,7 +765,6 @@ virHostdevReattachPCIDevice(virHostdevManagerPtr mgr,
                   err ? err->message : _("unknown error"));
         virResetError(err);
     }
-    virPCIDeviceFree(actual);
 }
 
 /* @oldStateDir:
@@ -836,17 +826,29 @@ virHostdevReAttachPCIDevices(virHostdevManagerPtr mgr,
             continue;
         }
 
+        i++;
+    }
+
+    /* Step 2: Move devices from the active list to the inactive list */
+    for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
+        virPCIDevicePtr pci = virPCIDeviceListGet(pcidevs, i);
+        virPCIDevicePtr actual;
+
         VIR_DEBUG("Removing PCI device %s from active list",
                   virPCIDeviceGetName(pci));
-        virPCIDeviceListDel(mgr->activePCIHostdevs, pci);
-        i++;
+        actual = virPCIDeviceListSteal(mgr->activePCIHostdevs, pci);
+
+        if (actual) {
+            VIR_DEBUG("Adding PCI device %s to inactive list",
+                      virPCIDeviceGetName(pci));
+            virPCIDeviceListAdd(mgr->inactivePCIHostdevs, actual);
+        }
     }
 
-    /* At this point, any device that had been used by the guest is in
-     * pcidevs, but has been removed from activePCIHostdevs.
-     */
+    /* At this point, any device that had been used by the guest has been
+     * moved to the inactive list */
 
-    /* Step 2: restore original network config of hostdevs that used
+    /* Step 3: restore original network config of hostdevs that used
      * <interface type='hostdev'>
      */
     for (i = 0; i < nhostdevs; i++) {
@@ -871,7 +873,7 @@ virHostdevReAttachPCIDevices(virHostdevManagerPtr mgr,
         }
     }
 
-    /* Step 3: perform a PCI Reset on all devices */
+    /* Step 4: perform a PCI Reset on all devices */
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr pci = virPCIDeviceListGet(pcidevs, i);
 
@@ -888,16 +890,26 @@ virHostdevReAttachPCIDevices(virHostdevManagerPtr mgr,
         }
     }
 
-    /* Step 4: reattach devices to their host drivers (if managed) or place
-     * them on the inactive list (if not managed)
-     */
-    while (virPCIDeviceListCount(pcidevs) > 0) {
-        virPCIDevicePtr pci = virPCIDeviceListStealIndex(pcidevs, 0);
-        virHostdevReattachPCIDevice(mgr, pci);
+    /* Step 5: Reattach managed devices to their host drivers; unmanaged
+     *         devices don't need to be processed further */
+    for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
+        virPCIDevicePtr pci = virPCIDeviceListGet(pcidevs, i);
+        virPCIDevicePtr actual;
+
+        /* We need to look up the actual device because that's what
+         * virHostdevReattachPCIDevice() expects as its argument */
+        if (!(actual = virPCIDeviceListFind(mgr->inactivePCIHostdevs, pci)))
+            continue;
+
+        if (virPCIDeviceGetManaged(actual))
+            virHostdevReattachPCIDevice(mgr, actual);
+        else
+            VIR_DEBUG("Not reattaching unmanaged PCI device %s",
+                      virPCIDeviceGetName(actual));
     }
 
-    virObjectUnref(pcidevs);
  cleanup:
+    virObjectUnref(pcidevs);
     virObjectUnlock(mgr->activePCIHostdevs);
     virObjectUnlock(mgr->inactivePCIHostdevs);
 }
-- 
2.5.0


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