[Qemu-devel] [PATCH v3 02/13] qdev: enhance global_prop_list_add()

[Peter Xu <peterx@redhat.com>]

Originally it can only alloc new entries and insert. Let it be smarter
that it can update existing fields, and even delete elements. This is
preparation of (finally) the replacement of x86_cpu_apply_props(). If
you see x86_cpu_apply_props(), it allows to skip entries when value is
NULL. Here, it works just like deleting an existing entry.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 hw/core/qdev-properties.c    | 28 +++++++++++++++++++++++++++-
 include/hw/qdev-properties.h | 10 ++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index 4b74382..dc3b0ac 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -1045,7 +1045,33 @@ static GList *global_props;
 GList *global_prop_list_add(GList *list, const char *driver,
                             const char *property, const char *value)
 {
-    GlobalProperty *p = g_new0(GlobalProperty, 1);
+    GList *l;
+    GlobalProperty *p;
+
+    /* Look up the (property, value) first in the list */
+    for (l = list; l; l = l->next) {
+        p = l->data;
+        if (!strcmp(driver, p->driver) && !strcmp(property, p->property)) {
+            if (value) {
+                /* Modify existing value */
+                p->value = value;
+            } else {
+                /* Delete this entry entirely */
+                list = g_list_remove_link(list, l);
+                g_free(p);
+                g_list_free(l);
+            }
+            return list;
+        }
+    }
+
+    /* Entry not exist. If we are deleting one entry, we're done. */
+    if (!value) {
+        return list;
+    }
+
+    /* If not found and value is set, we try to create a new entry */
+    p = g_new0(GlobalProperty, 1);
 
     /* These properties cannot fail the apply */
     p->errp = &error_abort;
diff --git a/include/hw/qdev-properties.h b/include/hw/qdev-properties.h
index 15ee6ba..55ad507 100644
--- a/include/hw/qdev-properties.h
+++ b/include/hw/qdev-properties.h
@@ -201,6 +201,16 @@ void qdev_prop_set_globals(DeviceState *dev);
 void error_set_from_qdev_prop_error(Error **errp, int ret, DeviceState *dev,
                                     Property *prop, const char *value);
 
+/*
+ * Register global property on the list. Elements of list should be
+ * GlobalProperty.
+ *
+ * - If (driver, property) is not existing on the list, create a new
+ *   one and link to the list.
+ * - If (driver, property) exists on the list, then:
+ *   - if value != NULL, update with new value
+ *   - if value == NULL, delete the entry
+ */
 GList *global_prop_list_add(GList *list, const char *driver,
                             const char *property, const char *value);
 void register_compat_prop(const char *driver, const char *property,
-- 
2.7.4