qapi: Use QAPI_LIST_PREPEND() where possible

Anywhere we create a list of just one item or by prepending items
(typically because order doesn't matter), we can use
QAPI_LIST_PREPEND().  But places where we must keep the list in order
by appending remain open-coded until later patches.

Note that as a side effect, this also performs a cleanup of two minor
issues in qga/commands-posix.c: the old code was performing
 new = g_malloc0(sizeof(*ret));
which 1) is confusing because you have to verify whether 'new' and
'ret' are variables with the same type, and 2) would conflict with C++
compilation (not an actual problem for this file, but makes
copy-and-paste harder).

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20201113011340.463563-5-eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
[Straightforward conflicts due to commit a8aa94b5f8 "qga: update
schema for guest-get-disks 'dependents' field" and commit a10b453a52
"target/mips: Move mips_cpu_add_definition() from helper.c to cpu.c"
resolved.  Commit message tweaked.]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index 65d8ff4849..73b79df7d8 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -1255,7 +1255,8 @@ void hmp_migrate_set_capability(Monitor *mon, const QDict *qdict)
     const char *cap = qdict_get_str(qdict, "capability");
     bool state = qdict_get_bool(qdict, "state");
     Error *err = NULL;
-    MigrationCapabilityStatusList *caps = g_malloc0(sizeof(*caps));
+    MigrationCapabilityStatusList *caps = NULL;
+    MigrationCapabilityStatus *value;
     int val;
 
     val = qapi_enum_parse(&MigrationCapability_lookup, cap, -1, &err);
@@ -1263,14 +1264,14 @@ void hmp_migrate_set_capability(Monitor *mon, const QDict *qdict)
         goto end;
     }
 
-    caps->value = g_malloc0(sizeof(*caps->value));
-    caps->value->capability = val;
-    caps->value->state = state;
-    caps->next = NULL;
+    value = g_malloc0(sizeof(*value));
+    value->capability = val;
+    value->state = state;
+    QAPI_LIST_PREPEND(caps, value);
     qmp_migrate_set_capabilities(caps, &err);
+    qapi_free_MigrationCapabilityStatusList(caps);
 
 end:
-    qapi_free_MigrationCapabilityStatusList(caps);
     hmp_handle_error(mon, err);
 }