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Re: [libvirt] [PATCH] xen: Use internal interfaces in xenDomainUsedCpus



On 16.07.2013 18:11, Stefan Bader wrote:
> Based on Daniel's feedback I did a split for public/private functions
> for those that cause the lockup when getting XML. Maybe not complete
> but at least seems to allow basic usage again (through virt-manager).
> 

As Jim hinted on "make syntax-check" I refreshed the patch with indentation
fixed up.

-Stefan

From 0df7a75cb777c2f616d5d0e16a6eb8b3db4b1f15 Mon Sep 17 00:00:00 2001
From: Stefan Bader <stefan bader canonical com>
Date: Mon, 15 Jul 2013 16:03:58 +0200
Subject: [PATCH] xen: Use internal interfaces in xenDomainUsedCpus

Since commit 95e18efd most public interfaces (xenUnified...) obtain
a virDomainDefPtr via xenGetDomainDefFor...() which take the unified
lock.
This is already taken before calling xenDomainUsedCpus(), so we get
a deadlock for active guests. Avoid this by splitting up
xenUnifiedDomainGetVcpusFlags() and xenUnifiedDomainGetVcpus() into
public and private function calls (which get the virDomainDefPtr passed)
and use those in xenDomainUsedCpus().

    xenDomainUsedCpus
      ...
      nb_vcpu = xenUnifiedDomainGetMaxVcpus(dom);
        return xenUnifiedDomainGetVcpusFlags(...)
          ...
          if (!(def = xenGetDomainDefForDom(dom)))
            return xenGetDomainDefForUUID(dom->conn, dom->uuid);
              ...
              ret = xenHypervisorLookupDomainByUUID(conn, uuid);
                ...
                xenUnifiedLock(priv);
                name = xenStoreDomainGetName(conn, id);
                xenUnifiedUnlock(priv);
      ...
      if ((ncpus = xenUnifiedDomainGetVcpus(dom, cpuinfo, nb_vcpu,
        ...
        if (!(def = xenGetDomainDefForDom(dom)))
          [again like above]

Signed-off-by: Stefan Bader <stefan bader canonical com>
---
 src/xen/xen_driver.c |   94 +++++++++++++++++++++++++++++++++-----------------
 src/xen/xen_driver.h |    2 +-
 2 files changed, 64 insertions(+), 32 deletions(-)

diff --git a/src/xen/xen_driver.c b/src/xen/xen_driver.c
index 39334b7..edd8447 100644
--- a/src/xen/xen_driver.c
+++ b/src/xen/xen_driver.c
@@ -73,12 +73,14 @@
 
 static int
 xenUnifiedNodeGetInfo(virConnectPtr conn, virNodeInfoPtr info);
+
 static int
-xenUnifiedDomainGetMaxVcpus(virDomainPtr dom);
+__xenUnifiedDomainGetVcpusFlags(virDomainPtr dom, virDomainDefPtr def,
+                                unsigned int flags);
 static int
-xenUnifiedDomainGetVcpus(virDomainPtr dom,
-                         virVcpuInfoPtr info, int maxinfo,
-                         unsigned char *cpumaps, int maplen);
+__xenUnifiedDomainGetVcpus(virDomainPtr dom, virDomainDefPtr def,
+                           virVcpuInfoPtr info, int maxinfo,
+                           unsigned char *cpumaps, int maplen);
 
 
 static bool is_privileged = false;
@@ -173,6 +175,7 @@ xenNumaInit(virConnectPtr conn) {
 /**
  * xenDomainUsedCpus:
  * @dom: the domain
+ * @def: the domain definition
  *
  * Analyze which set of CPUs are used by the domain and
  * return a string providing the ranges.
@@ -181,7 +184,7 @@ xenNumaInit(virConnectPtr conn) {
  *         NULL if the domain uses all CPU or in case of error.
  */
 char *
-xenDomainUsedCpus(virDomainPtr dom)
+xenDomainUsedCpus(virDomainPtr dom, virDomainDefPtr def)
 {
     char *res = NULL;
     int ncpus;
@@ -202,9 +205,14 @@ xenDomainUsedCpus(virDomainPtr dom)
 
     if (priv->nbNodeCpus <= 0)
         return NULL;
-    nb_vcpu = xenUnifiedDomainGetMaxVcpus(dom);
+    nb_vcpu = __xenUnifiedDomainGetVcpusFlags(dom, def,
+                                              (VIR_DOMAIN_VCPU_LIVE |
+                                               VIR_DOMAIN_VCPU_MAXIMUM));
     if (nb_vcpu <= 0)
         return NULL;
+    /* FIXME: To be consistent this should map to an internal interface, too.
+     * Currently it actually does map straight to xenDaemonNodeGetInfo().
+     */
     if (xenUnifiedNodeGetInfo(dom->conn, &nodeinfo) < 0)
         return NULL;
 
@@ -217,8 +225,8 @@ xenDomainUsedCpus(virDomainPtr dom)
         VIR_ALLOC_N(cpumap, nb_vcpu * cpumaplen) < 0)
         goto done;
 
-    if ((ncpus = xenUnifiedDomainGetVcpus(dom, cpuinfo, nb_vcpu,
-                                          cpumap, cpumaplen)) >= 0) {
+    if ((ncpus = __xenUnifiedDomainGetVcpus(dom, def, cpuinfo, nb_vcpu,
+                                            cpumap, cpumaplen)) >= 0) {
         for (n = 0; n < ncpus; n++) {
             for (m = 0; m < priv->nbNodeCpus; m++) {
                 bool used;
@@ -1410,54 +1418,57 @@ cleanup:
 }
 
 static int
-xenUnifiedDomainGetVcpus(virDomainPtr dom,
-                         virVcpuInfoPtr info, int maxinfo,
-                         unsigned char *cpumaps, int maplen)
+__xenUnifiedDomainGetVcpus(virDomainPtr dom, virDomainDefPtr def,
+                           virVcpuInfoPtr info, int maxinfo,
+                           unsigned char *cpumaps, int maplen)
 {
     xenUnifiedPrivatePtr priv = dom->conn->privateData;
-    virDomainDefPtr def = NULL;
     int ret = -1;
 
-    if (!(def = xenGetDomainDefForDom(dom)))
-        goto cleanup;
-
-    if (virDomainGetVcpusEnsureACL(dom->conn, def) < 0)
-        goto cleanup;
-
     if (dom->id < 0) {
         if (priv->xendConfigVersion < XEND_CONFIG_VERSION_3_0_4) {
             virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                            _("Cannot get VCPUs of inactive domain"));
-            goto cleanup;
         } else {
-            ret = xenDaemonDomainGetVcpus(dom->conn, def, info, maxinfo, cpumaps, maplen);
+            ret = xenDaemonDomainGetVcpus(dom->conn, def, info, maxinfo,
+                                          cpumaps, maplen);
         }
     } else {
-        ret = xenHypervisorGetVcpus(dom->conn, def, info, maxinfo, cpumaps, maplen);
+        ret = xenHypervisorGetVcpus(dom->conn, def, info, maxinfo, cpumaps,
+                                    maplen);
     }
 
-cleanup:
-    virDomainDefFree(def);
     return ret;
 }
 
 static int
-xenUnifiedDomainGetVcpusFlags(virDomainPtr dom, unsigned int flags)
+xenUnifiedDomainGetVcpus(virDomainPtr dom,
+                         virVcpuInfoPtr info, int maxinfo,
+                         unsigned char *cpumaps, int maplen)
 {
-    xenUnifiedPrivatePtr priv = dom->conn->privateData;
     virDomainDefPtr def = NULL;
     int ret = -1;
 
-    virCheckFlags(VIR_DOMAIN_VCPU_LIVE |
-                  VIR_DOMAIN_VCPU_CONFIG |
-                  VIR_DOMAIN_VCPU_MAXIMUM, -1);
-
     if (!(def = xenGetDomainDefForDom(dom)))
         goto cleanup;
 
-    if (virDomainGetVcpusFlagsEnsureACL(dom->conn, def) < 0)
+    if (virDomainGetVcpusEnsureACL(dom->conn, def) < 0)
         goto cleanup;
 
+    ret = __xenUnifiedDomainGetVcpus(dom, def, info, maxinfo, cpumaps, maplen);
+
+cleanup:
+    virDomainDefFree(def);
+    return ret;
+}
+
+static int
+__xenUnifiedDomainGetVcpusFlags(virDomainPtr dom, virDomainDefPtr def,
+                                unsigned int flags)
+{
+    xenUnifiedPrivatePtr priv = dom->conn->privateData;
+    int ret = -1;
+
     if (dom->id < 0) {
         if (priv->xendConfigVersion < XEND_CONFIG_VERSION_3_0_4)
             ret = xenXMDomainGetVcpusFlags(dom->conn, def, flags);
@@ -1470,6 +1481,27 @@ xenUnifiedDomainGetVcpusFlags(virDomainPtr dom, unsigned int flags)
             ret = xenDaemonDomainGetVcpusFlags(dom->conn, def, flags);
     }
 
+   return ret;
+}
+
+static int
+xenUnifiedDomainGetVcpusFlags(virDomainPtr dom, unsigned int flags)
+{
+    virDomainDefPtr def = NULL;
+    int ret = -1;
+
+    virCheckFlags(VIR_DOMAIN_VCPU_LIVE |
+                  VIR_DOMAIN_VCPU_CONFIG |
+                  VIR_DOMAIN_VCPU_MAXIMUM, -1);
+
+    if (!(def = xenGetDomainDefForDom(dom)))
+        goto cleanup;
+
+    if (virDomainGetVcpusFlagsEnsureACL(dom->conn, def) < 0)
+        goto cleanup;
+
+    ret = __xenUnifiedDomainGetVcpusFlags(dom, def, flags);
+
 cleanup:
     virDomainDefFree(def);
     return ret;
@@ -1501,7 +1533,7 @@ xenUnifiedDomainGetXMLDesc(virDomainPtr dom, unsigned int flags)
     } else {
         char *cpus;
         xenUnifiedLock(priv);
-        cpus = xenDomainUsedCpus(dom);
+        cpus = xenDomainUsedCpus(dom, def);
         xenUnifiedUnlock(priv);
         def = xenDaemonDomainGetXMLDesc(dom->conn, minidef, cpus);
         VIR_FREE(cpus);
diff --git a/src/xen/xen_driver.h b/src/xen/xen_driver.h
index 3c7a8cd..a363161 100644
--- a/src/xen/xen_driver.h
+++ b/src/xen/xen_driver.h
@@ -187,7 +187,7 @@ struct _xenUnifiedPrivate {
 
 typedef struct _xenUnifiedPrivate *xenUnifiedPrivatePtr;
 
-char *xenDomainUsedCpus(virDomainPtr dom);
+char *xenDomainUsedCpus(virDomainPtr dom, virDomainDefPtr def);
 
 virDomainXMLOptionPtr xenDomainXMLConfInit(void);
 
-- 
1.7.9.5

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