From 4ae9dbea99cf20f0f33f60e63f2d7296bf3873e3 Mon Sep 17 00:00:00 2001
From: John Ferlan <jferlan@redhat.com>
Date: Thu, 29 Jun 2017 15:50:06 -0400
Subject: [PATCH] nodedev: Convert virNodeDeviceObjListPtr to use hash tables

Rather than use a forward linked list of elements, it'll be much more
efficient to use a hash table to reference the elements by unique name
and to perform hash searches.

This patch does all the heavy lifting of converting the list object to
use a self locking list that contains the hash table. Each of the FindBy
functions that do not involve finding the object by it's key (name) is
converted to use virHashSearch in order to find the specific object.
When searching for the key (name), it's possible to use virHashLookup.
For any of the list perusal functions that are required to evaluate
each object, the virHashForEach function is used.
---
 src/conf/virnodedeviceobj.c | 560 ++++++++++++++++++++++++------------
 1 file changed, 378 insertions(+), 182 deletions(-)

diff --git a/src/conf/virnodedeviceobj.c b/src/conf/virnodedeviceobj.c
index 035a56dad8..3ab93a3ea6 100644
--- a/src/conf/virnodedeviceobj.c
+++ b/src/conf/virnodedeviceobj.c
@@ -25,6 +25,7 @@
 #include "viralloc.h"
 #include "virnodedeviceobj.h"
 #include "virerror.h"
+#include "virhash.h"
 #include "virlog.h"
 #include "virstring.h"
 
@@ -39,13 +40,19 @@ struct _virNodeDeviceObj {
 };
 
 struct _virNodeDeviceObjList {
-    size_t count;
-    virNodeDeviceObjPtr *objs;
+    virObjectLockable parent;
+
+    /* name string -> virNodeDeviceObj mapping
+     * for O(1), lockless lookup-by-name */
+    virHashTable *objs;
+
 };
 
 
 static virClassPtr virNodeDeviceObjClass;
+static virClassPtr virNodeDeviceObjListClass;
 static void virNodeDeviceObjDispose(void *opaque);
+static void virNodeDeviceObjListDispose(void *opaque);
 
 static int
 virNodeDeviceObjOnceInit(void)
@@ -56,6 +63,12 @@ virNodeDeviceObjOnceInit(void)
                                               virNodeDeviceObjDispose)))
         return -1;
 
+    if (!(virNodeDeviceObjListClass = virClassNew(virClassForObjectLockable(),
+                                                  "virNodeDeviceObjList",
+                                                  sizeof(virNodeDeviceObjList),
+                                                  virNodeDeviceObjListDispose)))
+        return -1;
+
     return 0;
 }
 
@@ -211,26 +224,57 @@ virNodeDeviceFindVPORTCapDef(const virNodeDeviceObj *obj)
 }
 
 
+static virNodeDeviceObjPtr
+virNodeDeviceObjListSearch(virNodeDeviceObjListPtr devs,
+                           virHashSearcher callback,
+                           const void *data)
+{
+    virNodeDeviceObjPtr obj;
+
+    virObjectLock(devs);
+    obj = virHashSearch(devs->objs, callback, data, NULL);
+    virObjectRef(obj);
+    virObjectUnlock(devs);
+
+    if (obj)
+        virObjectLock(obj);
+
+    return obj;
+}
+
+
+static int
+virNodeDeviceObjListFindBySysfsPathCallback(const void *payload,
+                                            const void *name ATTRIBUTE_UNUSED,
+                                            const void *opaque)
+{
+    virNodeDeviceObjPtr obj = (virNodeDeviceObjPtr) payload;
+    const char *sysfs_path = opaque;
+    int want = 0;
+
+    virObjectLock(obj);
+    if (STREQ_NULLABLE(obj->def->sysfs_path, sysfs_path))
+        want = 1;
+    virObjectUnlock(obj);
+    return want;
+}
+
+
 virNodeDeviceObjPtr
 virNodeDeviceObjListFindBySysfsPath(virNodeDeviceObjListPtr devs,
                                     const char *sysfs_path)
 {
-    size_t i;
+    return virNodeDeviceObjListSearch(devs,
+                                      virNodeDeviceObjListFindBySysfsPathCallback,
+                                      sysfs_path);
+}
 
-    for (i = 0; i < devs->count; i++) {
-        virNodeDeviceObjPtr obj = devs->objs[i];
-        virNodeDeviceDefPtr def;
 
-        virObjectLock(obj);
-        def = obj->def;
-        if ((def->sysfs_path != NULL) &&
-            (STREQ(def->sysfs_path, sysfs_path))) {
-            return virObjectRef(obj);
-        }
-        virObjectUnlock(obj);
-    }
-
-    return NULL;
+static virNodeDeviceObjPtr
+virNodeDeviceObjListFindByNameLocked(virNodeDeviceObjListPtr devs,
+                                     const char *name)
+{
+    return virObjectRef(virHashLookup(devs->objs, name));
 }
 
 
@@ -238,20 +282,42 @@ virNodeDeviceObjPtr
 virNodeDeviceObjListFindByName(virNodeDeviceObjListPtr devs,
                                const char *name)
 {
-    size_t i;
-
-    for (i = 0; i < devs->count; i++) {
-        virNodeDeviceObjPtr obj = devs->objs[i];
-        virNodeDeviceDefPtr def;
+    virNodeDeviceObjPtr obj;
 
+    virObjectLock(devs);
+    obj = virNodeDeviceObjListFindByNameLocked(devs, name);
+    virObjectUnlock(devs);
+    if (obj)
         virObjectLock(obj);
-        def = obj->def;
-        if (STREQ(def->name, name))
-            return virObjectRef(obj);
-        virObjectUnlock(obj);
-    }
 
-    return NULL;
+    return obj;
+}
+
+
+struct virNodeDeviceObjListFindByWWNsData {
+    const char *parent_wwnn;
+    const char *parent_wwpn;
+};
+
+static int
+virNodeDeviceObjListFindByWWNsCallback(const void *payload,
+                                       const void *name ATTRIBUTE_UNUSED,
+                                       const void *opaque)
+{
+    virNodeDeviceObjPtr obj = (virNodeDeviceObjPtr) payload;
+    struct virNodeDeviceObjListFindByWWNsData *data =
+        (struct virNodeDeviceObjListFindByWWNsData *) opaque;
+    virNodeDevCapsDefPtr cap;
+    int want = 0;
+
+    virObjectLock(obj);
+    if ((cap = virNodeDeviceFindFCCapDef(obj)) &&
+        STREQ_NULLABLE(cap->data.scsi_host.wwnn, data->parent_wwnn) &&
+        STREQ_NULLABLE(cap->data.scsi_host.wwpn, data->parent_wwpn) &&
+        virNodeDeviceFindVPORTCapDef(obj))
+        want = 1;
+    virObjectUnlock(obj);
+    return want;
 }
 
 
@@ -260,22 +326,32 @@ virNodeDeviceObjListFindByWWNs(virNodeDeviceObjListPtr devs,
                                const char *parent_wwnn,
                                const char *parent_wwpn)
 {
-    size_t i;
+    struct virNodeDeviceObjListFindByWWNsData data = {
+        .parent_wwnn = parent_wwnn, .parent_wwpn = parent_wwpn };
 
-    for (i = 0; i < devs->count; i++) {
-        virNodeDeviceObjPtr obj = devs->objs[i];
-        virNodeDevCapsDefPtr cap;
+    return virNodeDeviceObjListSearch(devs,
+                                      virNodeDeviceObjListFindByWWNsCallback,
+                                      &data);
+}
 
-        virObjectLock(obj);
-        if ((cap = virNodeDeviceFindFCCapDef(obj)) &&
-            STREQ_NULLABLE(cap->data.scsi_host.wwnn, parent_wwnn) &&
-            STREQ_NULLABLE(cap->data.scsi_host.wwpn, parent_wwpn) &&
-            virNodeDeviceFindVPORTCapDef(obj))
-            return virObjectRef(obj);
-        virObjectUnlock(obj);
-    }
 
-    return NULL;
+static int
+virNodeDeviceObjListFindByFabricWWNCallback(const void *payload,
+                                            const void *name ATTRIBUTE_UNUSED,
+                                            const void *opaque)
+{
+    virNodeDeviceObjPtr obj = (virNodeDeviceObjPtr) payload;
+    const char *matchstr = opaque;
+    virNodeDevCapsDefPtr cap;
+    int want = 0;
+
+    virObjectLock(obj);
+    if ((cap = virNodeDeviceFindFCCapDef(obj)) &&
+        STREQ_NULLABLE(cap->data.scsi_host.fabric_wwn, matchstr) &&
+        virNodeDeviceFindVPORTCapDef(obj))
+        want = 1;
+    virObjectUnlock(obj);
+    return want;
 }
 
 
@@ -283,21 +359,26 @@ static virNodeDeviceObjPtr
 virNodeDeviceObjListFindByFabricWWN(virNodeDeviceObjListPtr devs,
                                     const char *parent_fabric_wwn)
 {
-    size_t i;
+    return virNodeDeviceObjListSearch(devs,
+                                      virNodeDeviceObjListFindByFabricWWNCallback,
+                                      parent_fabric_wwn);
+}
 
-    for (i = 0; i < devs->count; i++) {
-        virNodeDeviceObjPtr obj = devs->objs[i];
-        virNodeDevCapsDefPtr cap;
 
-        virObjectLock(obj);
-        if ((cap = virNodeDeviceFindFCCapDef(obj)) &&
-            STREQ_NULLABLE(cap->data.scsi_host.fabric_wwn, parent_fabric_wwn) &&
-            virNodeDeviceFindVPORTCapDef(obj))
-            return virObjectRef(obj);
-        virObjectUnlock(obj);
-    }
+static int
+virNodeDeviceObjListFindByCapCallback(const void *payload,
+                                      const void *name ATTRIBUTE_UNUSED,
+                                      const void *opaque)
+{
+    virNodeDeviceObjPtr obj = (virNodeDeviceObjPtr) payload;
+    const char *matchstr = opaque;
+    int want = 0;
 
-    return NULL;
+    virObjectLock(obj);
+    if (virNodeDeviceObjHasCap(obj, matchstr))
+        want = 1;
+    virObjectUnlock(obj);
+    return want;
 }
 
 
@@ -305,18 +386,48 @@ static virNodeDeviceObjPtr
 virNodeDeviceObjListFindByCap(virNodeDeviceObjListPtr devs,
                               const char *cap)
 {
-    size_t i;
+    return virNodeDeviceObjListSearch(devs,
+                                      virNodeDeviceObjListFindByCapCallback,
+                                      cap);
+}
 
-    for (i = 0; i < devs->count; i++) {
-        virNodeDeviceObjPtr obj = devs->objs[i];
 
-        virObjectLock(obj);
-        if (virNodeDeviceObjHasCap(obj, cap))
-            return virObjectRef(obj);
-        virObjectUnlock(obj);
-    }
+struct virNodeDeviceObjListFindSCSIHostByWWNsData {
+    const char *wwnn;
+    const char *wwpn;
+};
 
-    return NULL;
+static int
+virNodeDeviceObjListFindSCSIHostByWWNsCallback(const void *payload,
+                                               const void *name ATTRIBUTE_UNUSED,
+                                               const void *opaque)
+{
+    virNodeDeviceObjPtr obj = (virNodeDeviceObjPtr) payload;
+    struct virNodeDeviceObjListFindSCSIHostByWWNsData *data =
+        (struct virNodeDeviceObjListFindSCSIHostByWWNsData *) opaque;
+    virNodeDevCapsDefPtr cap;
+    int want = 0;
+
+    virObjectLock(obj);
+    cap = obj->def->caps;
+
+    while (cap) {
+        if (cap->data.type == VIR_NODE_DEV_CAP_SCSI_HOST) {
+            virNodeDeviceGetSCSIHostCaps(&cap->data.scsi_host);
+            if (cap->data.scsi_host.flags &
+                VIR_NODE_DEV_CAP_FLAG_HBA_FC_HOST) {
+                if (STREQ(cap->data.scsi_host.wwnn, data->wwnn) &&
+                    STREQ(cap->data.scsi_host.wwpn, data->wwpn)) {
+                    want = 1;
+                    break;
+                }
+            }
+        }
+        cap = cap->next;
+     }
+
+    virObjectUnlock(obj);
+    return want;
 }
 
 
@@ -325,31 +436,21 @@ virNodeDeviceObjListFindSCSIHostByWWNs(virNodeDeviceObjListPtr devs,
                                        const char *wwnn,
                                        const char *wwpn)
 {
-    size_t i;
+    struct virNodeDeviceObjListFindSCSIHostByWWNsData data = {
+        .wwnn = wwnn, .wwpn = wwpn };
 
-    for (i = 0; i < devs->count; i++) {
-        virNodeDeviceObjPtr obj = devs->objs[i];
-        virNodeDevCapsDefPtr cap;
+    return virNodeDeviceObjListSearch(devs,
+                                      virNodeDeviceObjListFindSCSIHostByWWNsCallback,
+                                      &data);
+}
 
-        virObjectLock(obj);
-        cap = obj->def->caps;
 
-        while (cap) {
-            if (cap->data.type == VIR_NODE_DEV_CAP_SCSI_HOST) {
-                virNodeDeviceGetSCSIHostCaps(&cap->data.scsi_host);
-                if (cap->data.scsi_host.flags &
-                    VIR_NODE_DEV_CAP_FLAG_HBA_FC_HOST) {
-                    if (STREQ(cap->data.scsi_host.wwnn, wwnn) &&
-                        STREQ(cap->data.scsi_host.wwpn, wwpn))
-                        return virObjectRef(obj);
-                }
-            }
-            cap = cap->next;
-        }
-        virObjectUnlock(obj);
-    }
+static void
+virNodeDeviceObjListDispose(void *obj)
+{
+    virNodeDeviceObjListPtr devs = obj;
 
-    return NULL;
+    virHashFree(devs->objs);
 }
 
 
@@ -358,8 +459,17 @@ virNodeDeviceObjListNew(void)
 {
     virNodeDeviceObjListPtr devs;
 
-    if (VIR_ALLOC(devs) < 0)
+    if (virNodeDeviceObjInitialize() < 0)
         return NULL;
+
+    if (!(devs = virObjectLockableNew(virNodeDeviceObjListClass)))
+        return NULL;
+
+    if (!(devs->objs = virHashCreate(50, virObjectFreeHashData))) {
+        virObjectUnref(devs);
+        return NULL;
+    }
+
     return devs;
 }
 
@@ -367,11 +477,7 @@ virNodeDeviceObjListNew(void)
 void
 virNodeDeviceObjListFree(virNodeDeviceObjListPtr devs)
 {
-    size_t i;
-    for (i = 0; i < devs->count; i++)
-        virObjectUnref(devs->objs[i]);
-    VIR_FREE(devs->objs);
-    VIR_FREE(devs);
+    virObjectUnref(devs);
 }
 
 
@@ -381,22 +487,28 @@ virNodeDeviceObjListAssignDef(virNodeDeviceObjListPtr devs,
 {
     virNodeDeviceObjPtr obj;
 
-    if ((obj = virNodeDeviceObjListFindByName(devs, def->name))) {
+    virObjectLock(devs);
+
+    if ((obj = virNodeDeviceObjListFindByNameLocked(devs, def->name))) {
+        virObjectLock(obj);
         virNodeDeviceDefFree(obj->def);
         obj->def = def;
-        return obj;
+    } else {
+        if (!(obj = virNodeDeviceObjNew()))
+            goto cleanup;
+
+        if (virHashAddEntry(devs->objs, def->name, obj) < 0) {
+            virNodeDeviceObjEndAPI(&obj);
+            goto cleanup;
+        }
+
+        obj->def = def;
+        virObjectRef(obj);
     }
 
-    if (!(obj = virNodeDeviceObjNew()))
-        return NULL;
-
-    if (VIR_APPEND_ELEMENT_COPY(devs->objs, devs->count, obj) < 0) {
-        virNodeDeviceObjEndAPI(&obj);
-        return NULL;
-    }
-    obj->def = def;
-
-    return virObjectRef(obj);
+ cleanup:
+    virObjectUnlock(devs);
+    return obj;
 }
 
 
@@ -404,21 +516,20 @@ void
 virNodeDeviceObjListRemove(virNodeDeviceObjListPtr devs,
                            virNodeDeviceObjPtr obj)
 {
-    size_t i;
+    virNodeDeviceDefPtr def;
 
+    if (!obj)
+        return;
+    def = obj->def;
+
+    virObjectRef(obj);
     virObjectUnlock(obj);
-
-    for (i = 0; i < devs->count; i++) {
-        virObjectLock(devs->objs[i]);
-        if (devs->objs[i] == obj) {
-            virObjectUnlock(devs->objs[i]);
-            virObjectUnref(devs->objs[i]);
-
-            VIR_DELETE_ELEMENT(devs->objs, i, devs->count);
-            break;
-        }
-        virObjectUnlock(devs->objs[i]);
-    }
+    virObjectLock(devs);
+    virObjectLock(obj);
+    virHashRemoveEntry(devs->objs, def->name);
+    virObjectUnlock(obj);
+    virObjectUnref(obj);
+    virObjectUnlock(devs);
 }
 
 
@@ -619,25 +730,89 @@ virNodeDeviceCapMatch(virNodeDeviceObjPtr obj,
 }
 
 
+struct virNodeDeviceCountData {
+    virConnectPtr conn;
+    virNodeDeviceObjListFilter aclfilter;
+    const char *matchstr;
+    int count;
+};
+
+static int
+virNodeDeviceObjListNumOfDevicesCallback(void *payload,
+                                         const void *name ATTRIBUTE_UNUSED,
+                                         void *opaque)
+{
+    virNodeDeviceObjPtr obj = payload;
+    virNodeDeviceDefPtr def;
+    struct virNodeDeviceCountData *data = opaque;
+    virNodeDeviceObjListFilter aclfilter = data->aclfilter;
+
+    virObjectLock(obj);
+    def = obj->def;
+    if ((!aclfilter || aclfilter(data->conn, def)) &&
+        (!data->matchstr || virNodeDeviceObjHasCap(obj, data->matchstr)))
+        data->count++;
+
+    virObjectUnlock(obj);
+    return 0;
+}
+
+
 int
 virNodeDeviceObjListNumOfDevices(virNodeDeviceObjListPtr devs,
                                  virConnectPtr conn,
                                  const char *cap,
                                  virNodeDeviceObjListFilter aclfilter)
 {
-    size_t i;
-    int ndevs = 0;
+    struct virNodeDeviceCountData data = {
+        .conn = conn, .aclfilter = aclfilter, .matchstr = cap, .count = 0 };
 
-    for (i = 0; i < devs->count; i++) {
-        virNodeDeviceObjPtr obj = devs->objs[i];
-        virObjectLock(obj);
-        if ((!aclfilter || aclfilter(conn, obj->def)) &&
-            (!cap || virNodeDeviceObjHasCap(obj, cap)))
-            ++ndevs;
-        virObjectUnlock(obj);
-    }
+    virObjectLock(devs);
+    virHashForEach(devs->objs, virNodeDeviceObjListNumOfDevicesCallback, &data);
+    virObjectUnlock(devs);
 
-    return ndevs;
+    return data.count;
+}
+
+
+struct virNodeDeviceGetNamesData {
+    virConnectPtr conn;
+    virNodeDeviceObjListFilter aclfilter;
+    const char *matchstr;
+    int nnames;
+    char **names;
+    int maxnames;
+    bool error;
+};
+
+static int
+virNodeDeviceObjListGetNamesCallback(void *payload,
+                                     const void *name ATTRIBUTE_UNUSED,
+                                     void *opaque)
+{
+    virNodeDeviceObjPtr obj = payload;
+    virNodeDeviceDefPtr def;
+    struct virNodeDeviceGetNamesData *data = opaque;
+    virNodeDeviceObjListFilter aclfilter = data->aclfilter;
+
+    if (data->error)
+        return 0;
+
+    virObjectLock(obj);
+    def = obj->def;
+
+    if ((!aclfilter || aclfilter(data->conn, def)) &&
+        (!data->matchstr || virNodeDeviceObjHasCap(obj, data->matchstr))) {
+        if (VIR_STRDUP(data->names[data->nnames], def->name) < 0) {
+            data->error = true;
+            goto cleanup;
+        }
+        data->nnames++;
+     }
+
+ cleanup:
+    virObjectUnlock(obj);
+    return 0;
 }
 
 
@@ -649,28 +824,22 @@ virNodeDeviceObjListGetNames(virNodeDeviceObjListPtr devs,
                              char **const names,
                              int maxnames)
 {
-    int nnames = 0;
-    size_t i;
+    struct virNodeDeviceGetNamesData data = {
+        .conn = conn, .aclfilter = aclfilter, .matchstr = cap, .names = names,
+        .nnames = 0, .maxnames = maxnames, .error = false };
 
-    for (i = 0; i < devs->count && nnames < maxnames; i++) {
-        virNodeDeviceObjPtr obj = devs->objs[i];
-        virObjectLock(obj);
-        if ((!aclfilter || aclfilter(conn, obj->def)) &&
-            (!cap || virNodeDeviceObjHasCap(obj, cap))) {
-            if (VIR_STRDUP(names[nnames], obj->def->name) < 0) {
-                virObjectUnlock(obj);
-                goto failure;
-            }
-            nnames++;
-        }
-        virObjectUnlock(obj);
-    }
+    virObjectLock(devs);
+    virHashForEach(devs->objs, virNodeDeviceObjListGetNamesCallback, &data);
+    virObjectUnlock(devs);
 
-    return nnames;
+    if (data.error)
+        goto error;
 
- failure:
-    while (--nnames >= 0)
-        VIR_FREE(names[nnames]);
+    return data.nnames;
+
+ error:
+    while (--data.nnames)
+        VIR_FREE(data.names[data.nnames]);
     return -1;
 }
 
@@ -707,6 +876,51 @@ virNodeDeviceMatch(virNodeDeviceObjPtr obj,
 #undef MATCH
 
 
+struct virNodeDeviceObjListExportData {
+    virConnectPtr conn;
+    virNodeDeviceObjListFilter aclfilter;
+    unsigned int flags;
+    virNodeDevicePtr *devices;
+    int ndevices;
+    bool error;
+};
+
+static int
+virNodeDeviceObjListExportCallback(void *payload,
+                                   const void *name ATTRIBUTE_UNUSED,
+                                   void *opaque)
+{
+    virNodeDeviceObjPtr obj = payload;
+    virNodeDeviceDefPtr def;
+    struct virNodeDeviceObjListExportData *data = opaque;
+    virNodeDevicePtr device = NULL;
+
+    if (data->error)
+        return 0;
+
+    virObjectLock(obj);
+    def = obj->def;
+
+    if ((!data->aclfilter || data->aclfilter(data->conn, def)) &&
+        virNodeDeviceMatch(obj, data->flags)) {
+        if (data->devices) {
+            if (!(device = virGetNodeDevice(data->conn, def->name)) ||
+                VIR_STRDUP(device->parent, def->parent) < 0) {
+                virObjectUnref(device);
+                data->error = true;
+                goto cleanup;
+            }
+            data->devices[data->ndevices] = device;
+        }
+        data->ndevices++;
+    }
+
+ cleanup:
+    virObjectUnlock(obj);
+    return 0;
+}
+
+
 int
 virNodeDeviceObjListExport(virConnectPtr conn,
                            virNodeDeviceObjListPtr devs,
@@ -714,49 +928,31 @@ virNodeDeviceObjListExport(virConnectPtr conn,
                            virNodeDeviceObjListFilter aclfilter,
                            unsigned int flags)
 {
-    virNodeDevicePtr *tmp_devices = NULL;
-    virNodeDevicePtr device = NULL;
-    int ndevices = 0;
-    int ret = -1;
-    size_t i;
+    struct virNodeDeviceObjListExportData data = {
+        .conn = conn, .aclfilter = aclfilter, .flags = flags,
+        .devices = NULL, .ndevices = 0, .error = false };
 
-    if (devices && VIR_ALLOC_N(tmp_devices, devs->count + 1) < 0)
+    virObjectLock(devs);
+    if (devices &&
+        VIR_ALLOC_N(data.devices, virHashSize(devs->objs) + 1) < 0) {
+        virObjectUnlock(devs);
+        return -1;
+    }
+
+    virHashForEach(devs->objs, virNodeDeviceObjListExportCallback, &data);
+    virObjectUnlock(devs);
+
+    if (data.error)
         goto cleanup;
 
-    for (i = 0; i < devs->count; i++) {
-        virNodeDeviceObjPtr obj = devs->objs[i];
-        virObjectLock(obj);
-        if ((!aclfilter || aclfilter(conn, obj->def)) &&
-            virNodeDeviceMatch(obj, flags)) {
-            if (devices) {
-                if (!(device = virGetNodeDevice(conn, obj->def->name)) ||
-                    VIR_STRDUP(device->parent, obj->def->parent) < 0) {
-                    virObjectUnref(device);
-                    virObjectUnlock(obj);
-                    goto cleanup;
-                }
-                tmp_devices[ndevices] = device;
-            }
-            ndevices++;
-        }
-        virObjectUnlock(obj);
-    }
+    if (data.devices) {
+        ignore_value(VIR_REALLOC_N(data.devices, data.ndevices + 1));
+        *devices = data.devices;
+     }
 
-    if (tmp_devices) {
-        /* trim the array to the final size */
-        ignore_value(VIR_REALLOC_N(tmp_devices, ndevices + 1));
-        *devices = tmp_devices;
-        tmp_devices = NULL;
-    }
-
-    ret = ndevices;
+    return data.ndevices;
 
  cleanup:
-    if (tmp_devices) {
-        for (i = 0; i < ndevices; i++)
-            virObjectUnref(tmp_devices[i]);
-    }
-
-    VIR_FREE(tmp_devices);
-    return ret;
+    virObjectListFree(data.devices);
+    return -1;
 }