qom: Change object_get_canonical_path_component() not to malloc

object_get_canonical_path_component() returns a malloced copy of a
property name on success, null on failure.

19 of its 25 callers immediately free the returned copy.

Change object_get_canonical_path_component() to return the property
name directly.  Since modifying the name would be wrong, adjust the
return type to const char *.

Drop the free from the 19 callers become simpler, add the g_strdup()
to the other six.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200714160202.3121879-4-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>

backends/hostmem.c

@@ -33,7 +33,7 @@ char *
 host_memory_backend_get_name(HostMemoryBackend *backend)
 {
     if (!backend->use_canonical_path) {
-        return object_get_canonical_path_component(OBJECT(backend));
+        return g_strdup(object_get_canonical_path_component(OBJECT(backend)));
     }
 
     return object_get_canonical_path(OBJECT(backend));

block/throttle-groups.c

@@ -771,7 +771,7 @@ static void throttle_group_obj_complete(UserCreatable *obj, Error **errp)
 
     /* set group name to object id if it exists */
     if (!tg->name && tg->parent_obj.parent) {
-        tg->name = object_get_canonical_path_component(OBJECT(obj));
+        tg->name = g_strdup(object_get_canonical_path_component(OBJECT(obj)));
     }
     /* We must have a group name at this point */
     assert(tg->name);

gdbstub.c

@@ -2059,7 +2059,7 @@ static void handle_query_thread_extra(GdbCmdContext *gdb_ctx, void *user_ctx)
         /* Print the CPU model and name in multiprocess mode */
         ObjectClass *oc = object_get_class(OBJECT(cpu));
         const char *cpu_model = object_class_get_name(oc);
-        g_autofree char *cpu_name =
+        const char *cpu_name =
             object_get_canonical_path_component(OBJECT(cpu));
         g_string_printf(rs, "%s %s [%s]", cpu_model, cpu_name,
                         cpu->halted ? "halted " : "running");

hw/arm/xlnx-zynqmp.c

@@ -190,7 +190,7 @@ static void xlnx_zynqmp_create_rpu(MachineState *ms, XlnxZynqMPState *s,
     qdev_prop_set_uint32(DEVICE(&s->rpu_cluster), "cluster-id", 1);
 
     for (i = 0; i < num_rpus; i++) {
-        char *name;
+        const char *name;
 
         object_initialize_child(OBJECT(&s->rpu_cluster), "rpu-cpu[*]",
                                 &s->rpu_cpu[i],
@@ -204,7 +204,6 @@ static void xlnx_zynqmp_create_rpu(MachineState *ms, XlnxZynqMPState *s,
         } else {
             s->boot_cpu_ptr = &s->rpu_cpu[i];
         }
-        g_free(name);
 
         object_property_set_bool(OBJECT(&s->rpu_cpu[i]), "reset-hivecs", true,
                                  &error_abort);
@@ -341,7 +340,7 @@ static void xlnx_zynqmp_realize(DeviceState *dev, Error **errp)
 
     /* Realize APUs before realizing the GIC. KVM requires this.  */
     for (i = 0; i < num_apus; i++) {
-        char *name;
+        const char *name;
 
         object_property_set_int(OBJECT(&s->apu_cpu[i]), "psci-conduit",
                                 QEMU_PSCI_CONDUIT_SMC, &error_abort);
@@ -354,7 +353,6 @@ static void xlnx_zynqmp_realize(DeviceState *dev, Error **errp)
         } else {
             s->boot_cpu_ptr = &s->apu_cpu[i];
         }
-        g_free(name);
 
         object_property_set_bool(OBJECT(&s->apu_cpu[i]), "has_el3", s->secure,
                                  NULL);

hw/block/nvme.c

@@ -1397,9 +1397,8 @@ static void nvme_check_constraints(NvmeCtrl *n, Error **errp)
 
     if (!n->params.cmb_size_mb && n->pmrdev) {
         if (host_memory_backend_is_mapped(n->pmrdev)) {
-            char *path = object_get_canonical_path_component(OBJECT(n->pmrdev));
+            error_setg(errp, "can't use already busy memdev: %s",
-            error_setg(errp, "can't use already busy memdev: %s", path);
+                       object_get_canonical_path_component(OBJECT(n->pmrdev)));
-            g_free(path);
             return;
         }
 

hw/core/machine-qmp-cmds.c

@@ -315,7 +315,7 @@ static int query_memdev(Object *obj, void *opaque)
 
         m->value = g_malloc0(sizeof(*m->value));
 
-        m->value->id = object_get_canonical_path_component(obj);
+        m->value->id = g_strdup(object_get_canonical_path_component(obj));
         m->value->has_id = !!m->value->id;
 
         m->value->size = object_property_get_uint(obj, "size",

hw/core/machine.c

@@ -1073,9 +1073,8 @@ MemoryRegion *machine_consume_memdev(MachineState *machine,
     MemoryRegion *ret = host_memory_backend_get_memory(backend);
 
     if (memory_region_is_mapped(ret)) {
-        char *path = object_get_canonical_path_component(OBJECT(backend));
+        error_report("memory backend %s can't be used multiple times.",
-        error_report("memory backend %s can't be used multiple times.", path);
+                     object_get_canonical_path_component(OBJECT(backend)));
-        g_free(path);
         exit(EXIT_FAILURE);
     }
     host_memory_backend_set_mapped(backend, true);

hw/mem/nvdimm.c

@@ -137,13 +137,12 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice *nvdimm, Error **errp)
 
     if (size <= nvdimm->label_size || !pmem_size) {
         HostMemoryBackend *hostmem = dimm->hostmem;
-        char *path = object_get_canonical_path_component(OBJECT(hostmem));
 
         error_setg(errp, "the size of memdev %s (0x%" PRIx64 ") is too "
                    "small to contain nvdimm label (0x%" PRIx64 ") and "
                    "aligned PMEM (0x%" PRIx64 ")",
-                   path, memory_region_size(mr), nvdimm->label_size, align);
+                   object_get_canonical_path_component(OBJECT(hostmem)),
-        g_free(path);
+                   memory_region_size(mr), nvdimm->label_size, align);
         return;
     }
 

hw/mem/pc-dimm.c

@@ -179,9 +179,8 @@ static void pc_dimm_realize(DeviceState *dev, Error **errp)
         error_setg(errp, "'" PC_DIMM_MEMDEV_PROP "' property is not set");
         return;
     } else if (host_memory_backend_is_mapped(dimm->hostmem)) {
-        char *path = object_get_canonical_path_component(OBJECT(dimm->hostmem));
+        error_setg(errp, "can't use already busy memdev: %s",
-        error_setg(errp, "can't use already busy memdev: %s", path);
+                   object_get_canonical_path_component(OBJECT(dimm->hostmem)));
-        g_free(path);
         return;
     }
     if (((nb_numa_nodes > 0) && (dimm->node >= nb_numa_nodes)) ||

hw/misc/ivshmem.c

@@ -1037,9 +1037,8 @@ static void ivshmem_plain_realize(PCIDevice *dev, Error **errp)
         error_setg(errp, "You must specify a 'memdev'");
         return;
     } else if (host_memory_backend_is_mapped(s->hostmem)) {
-        char *path = object_get_canonical_path_component(OBJECT(s->hostmem));
+        error_setg(errp, "can't use already busy memdev: %s",
-        error_setg(errp, "can't use already busy memdev: %s", path);
+                   object_get_canonical_path_component(OBJECT(s->hostmem)));
-        g_free(path);
         return;
     }
 

hw/ppc/spapr_drc.c

@@ -513,7 +513,7 @@ static void realize(DeviceState *d, Error **errp)
     SpaprDrc *drc = SPAPR_DR_CONNECTOR(d);
     Object *root_container;
     gchar *link_name;
-    char *child_name;
+    const char *child_name;
 
     trace_spapr_drc_realize(spapr_drc_index(drc));
     /* NOTE: we do this as part of realize/unrealize due to the fact
@@ -529,7 +529,6 @@ static void realize(DeviceState *d, Error **errp)
     trace_spapr_drc_realize_child(spapr_drc_index(drc), child_name);
     object_property_add_alias(root_container, link_name,
                               drc->owner, child_name);
-    g_free(child_name);
     g_free(link_name);
     vmstate_register(VMSTATE_IF(drc), spapr_drc_index(drc), &vmstate_spapr_drc,
                      drc);

hw/ppc/trace-events

@@ -57,7 +57,7 @@ spapr_drc_detach(uint32_t index) "drc: 0x%"PRIx32
 spapr_drc_awaiting_quiesce(uint32_t index) "drc: 0x%"PRIx32
 spapr_drc_reset(uint32_t index) "drc: 0x%"PRIx32
 spapr_drc_realize(uint32_t index) "drc: 0x%"PRIx32
-spapr_drc_realize_child(uint32_t index, char *childname) "drc: 0x%"PRIx32", child name: %s"
+spapr_drc_realize_child(uint32_t index, const char *childname) "drc: 0x%"PRIx32", child name: %s"
 spapr_drc_realize_complete(uint32_t index) "drc: 0x%"PRIx32
 spapr_drc_unrealize(uint32_t index) "drc: 0x%"PRIx32
 

hw/virtio/virtio-crypto.c

@@ -786,9 +786,8 @@ static void virtio_crypto_device_realize(DeviceState *dev, Error **errp)
         error_setg(errp, "'cryptodev' parameter expects a valid object");
         return;
     } else if (cryptodev_backend_is_used(vcrypto->cryptodev)) {
-        char *path = object_get_canonical_path_component(OBJECT(vcrypto->conf.cryptodev));
+        error_setg(errp, "can't use already used cryptodev backend: %s",
-        error_setg(errp, "can't use already used cryptodev backend: %s", path);
+                   object_get_canonical_path_component(OBJECT(vcrypto->conf.cryptodev)));
-        g_free(path);
         return;
     }
 

hw/virtio/virtio-mem.c

@@ -409,11 +409,9 @@ static void virtio_mem_device_realize(DeviceState *dev, Error **errp)
         error_setg(errp, "'%s' property is not set", VIRTIO_MEM_MEMDEV_PROP);
         return;
     } else if (host_memory_backend_is_mapped(vmem->memdev)) {
-        char *path = object_get_canonical_path_component(OBJECT(vmem->memdev));
-
         error_setg(errp, "'%s' property specifies a busy memdev: %s",
-                   VIRTIO_MEM_MEMDEV_PROP, path);
+                   VIRTIO_MEM_MEMDEV_PROP,
-        g_free(path);
+                   object_get_canonical_path_component(OBJECT(vmem->memdev)));
         return;
     } else if (!memory_region_is_ram(&vmem->memdev->mr) ||
         memory_region_is_rom(&vmem->memdev->mr) ||

hw/virtio/virtio-pmem.c

@@ -112,9 +112,8 @@ static void virtio_pmem_realize(DeviceState *dev, Error **errp)
     }
 
     if (host_memory_backend_is_mapped(pmem->memdev)) {
-        char *path = object_get_canonical_path_component(OBJECT(pmem->memdev));
+        error_setg(errp, "can't use already busy memdev: %s",
-        error_setg(errp, "can't use already busy memdev: %s", path);
+                   object_get_canonical_path_component(OBJECT(pmem->memdev)));
-        g_free(path);
         return;
     }
 

include/qom/object.h

@@ -1462,7 +1462,7 @@ Object *object_get_internal_root(void);
  * path is the path within the composition tree starting from the root.
  * %NULL if the object doesn't have a parent (and thus a canonical path).
  */
-char *object_get_canonical_path_component(const Object *obj);
+const char *object_get_canonical_path_component(const Object *obj);
 
 /**
  * object_get_canonical_path:

iothread.c

@@ -165,7 +165,7 @@ static void iothread_complete(UserCreatable *obj, Error **errp)
 {
     Error *local_error = NULL;
     IOThread *iothread = IOTHREAD(obj);
-    char *name, *thread_name;
+    char *thread_name;
 
     iothread->stopping = false;
     iothread->running = true;
@@ -195,12 +195,11 @@ static void iothread_complete(UserCreatable *obj, Error **errp)
     /* This assumes we are called from a thread with useful CPU affinity for us
      * to inherit.
      */
-    name = object_get_canonical_path_component(OBJECT(obj));
+    thread_name = g_strdup_printf("IO %s",
-    thread_name = g_strdup_printf("IO %s", name);
+                        object_get_canonical_path_component(OBJECT(obj)));
     qemu_thread_create(&iothread->thread, thread_name, iothread_run,
                        iothread, QEMU_THREAD_JOINABLE);
     g_free(thread_name);
-    g_free(name);
 
     /* Wait for initialization to complete */
     while (iothread->thread_id == -1) {
@@ -303,7 +302,7 @@ type_init(iothread_register_types)
 
 char *iothread_get_id(IOThread *iothread)
 {
-    return object_get_canonical_path_component(OBJECT(iothread));
+    return g_strdup(object_get_canonical_path_component(OBJECT(iothread)));
 }
 
 AioContext *iothread_get_aio_context(IOThread *iothread)

net/net.c

@@ -1185,12 +1185,10 @@ void print_net_client(Monitor *mon, NetClientState *nc)
         monitor_printf(mon, "filters:\n");
     }
     QTAILQ_FOREACH(nf, &nc->filters, next) {
-        char *path = object_get_canonical_path_component(OBJECT(nf));
+        monitor_printf(mon, "  - %s: type=%s",
-
+                       object_get_canonical_path_component(OBJECT(nf)),
-        monitor_printf(mon, "  - %s: type=%s", path,
                        object_get_typename(OBJECT(nf)));
         netfilter_print_info(mon, nf);
-        g_free(path);
     }
 }
 

qom/object.c

@@ -1931,7 +1931,7 @@ object_property_add_const_link(Object *obj, const char *name,
                                 NULL, OBJ_PROP_LINK_DIRECT);
 }
 
-char *object_get_canonical_path_component(const Object *obj)
+const char *object_get_canonical_path_component(const Object *obj)
 {
     ObjectProperty *prop = NULL;
     GHashTableIter iter;
@@ -1947,7 +1947,7 @@ char *object_get_canonical_path_component(const Object *obj)
         }
 
         if (prop->opaque == obj) {
-            return g_strdup(prop->name);
+            return prop->name;
         }
     }
 
@@ -1966,7 +1966,7 @@ char *object_get_canonical_path(const Object *obj)
     }
 
     do {
-        char *component = object_get_canonical_path_component(obj);
+        const char *component = object_get_canonical_path_component(obj);
 
         if (!component) {
             /* A canonical path must be complete, so discard what was
@@ -1978,7 +1978,6 @@ char *object_get_canonical_path(const Object *obj)
 
         newpath = g_strdup_printf("/%s%s", component, path ? path : "");
         g_free(path);
-        g_free(component);
         path = newpath;
         obj = obj->parent;
     } while (obj != root);

qom/qom-hmp-cmds.c

@@ -96,10 +96,8 @@ static void print_qom_composition(Monitor *mon, Object *obj, int indent);
 
 static int qom_composition_compare(const void *a, const void *b, void *ignore)
 {
-    g_autofree char *ac = object_get_canonical_path_component(a);
+    return g_strcmp0(object_get_canonical_path_component(a),
-    g_autofree char *bc = object_get_canonical_path_component(b);
+                     object_get_canonical_path_component(b));
-
-    return g_strcmp0(ac, bc);
 }
 
 static int insert_qom_composition_child(Object *obj, void *opaque)
@@ -112,18 +110,17 @@ static int insert_qom_composition_child(Object *obj, void *opaque)
 
 static void print_qom_composition(Monitor *mon, Object *obj, int indent)
 {
-    char *name;
+    const char *name;
     GQueue children;
     Object *child;
 
     if (obj == object_get_root()) {
-        name = g_strdup("");
+        name = "";
     } else {
         name = object_get_canonical_path_component(obj);
     }
     monitor_printf(mon, "%*s/%s (%s)\n", indent, "", name,
                    object_get_typename(obj));
-    g_free(name);
 
     g_queue_init(&children);
     object_child_foreach(obj, insert_qom_composition_child, &children);

scsi/pr-manager-helper.c

@@ -42,11 +42,10 @@ typedef struct PRManagerHelper {
 
 static void pr_manager_send_status_changed_event(PRManagerHelper *pr_mgr)
 {
-    char *id = object_get_canonical_path_component(OBJECT(pr_mgr));
+    const char *id = object_get_canonical_path_component(OBJECT(pr_mgr));
 
     if (id) {
         qapi_event_send_pr_manager_status_changed(id, !!pr_mgr->ioc);
-        g_free(id);
     }
 }
 

scsi/pr-manager.c

@@ -128,7 +128,7 @@ static int query_one_pr_manager(Object *object, void *opaque)
 
     elem = g_new0(PRManagerInfoList, 1);
     info = g_new0(PRManagerInfo, 1);
-    info->id = object_get_canonical_path_component(object);
+    info->id = g_strdup(object_get_canonical_path_component(object));
     info->connected = pr_manager_is_connected(pr_mgr);
     elem->value = info;
     elem->next = NULL;

softmmu/memory.c

@@ -1764,7 +1764,7 @@ const char *memory_region_name(const MemoryRegion *mr)
 {
     if (!mr->name) {
         ((MemoryRegion *)mr)->name =
-            object_get_canonical_path_component(OBJECT(mr));
+            g_strdup(object_get_canonical_path_component(OBJECT(mr)));
     }
     return mr->name;
 }