[RFC v5 059/126] virtio-rng: introduce ERRP_AUTO_PROPAGATE

[Vladimir Sementsov-Ogievskiy]

If we want to add some info to errp (by error_prepend() or
error_append_hint()), we must use the ERRP_AUTO_PROPAGATE macro.
Otherwise, this info will not be added when errp == &fatal_err
(the program will exit prior to the error_append_hint() or
error_prepend() call).  Fix such cases.

If we want to check error after errp-function call, we need to
introduce local_err and than propagate it to errp. Instead, use
ERRP_AUTO_PROPAGATE macro, benefits are:
1. No need of explicit error_propagate call
2. No need of explicit local_err variable: use errp directly
3. ERRP_AUTO_PROPAGATE leaves errp as is if it's not NULL or
   &error_fatel, this means that we don't break error_abort
   (we'll abort on error_set, not on error_propagate)

This commit (together with its neighbors) was generated by

for f in $(git grep -l errp \*.[ch]); do \
    spatch --sp-file scripts/coccinelle/auto-propagated-errp.cocci \
    --macro-file scripts/cocci-macro-file.h --in-place --no-show-diff $f; \
done;

then fix a bit of compilation problems: coccinelle for some reason
leaves several
f() {
    ...
    goto out;
    ...
    out:
}
patterns, with "out:" at function end.

then
./python/commit-per-subsystem.py MAINTAINERS "$(< auto-msg)"

(auto-msg was a file with this commit message)

Still, for backporting it may be more comfortable to use only the first
command and then do one huge commit.

Reported-by: Kevin Wolf <address@hidden>
Reported-by: Greg Kurz <address@hidden>
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 backends/rng.c         | 7 +++----
 hw/virtio/virtio-rng.c | 7 +++----
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/backends/rng.c b/backends/rng.c
index 391888b8b3..aa3b85f418 100644
--- a/backends/rng.c
+++ b/backends/rng.c
@@ -53,9 +53,9 @@ static void rng_backend_complete(UserCreatable *uc, Error 
**errp)
 
 static void rng_backend_prop_set_opened(Object *obj, bool value, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     RngBackend *s = RNG_BACKEND(obj);
     RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
-    Error *local_err = NULL;
 
     if (value == s->opened) {
         return;
@@ -67,9 +67,8 @@ static void rng_backend_prop_set_opened(Object *obj, bool 
value, Error **errp)
     }
 
     if (k->opened) {
-        k->opened(s, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        k->opened(s, errp);
+        if (*errp) {
             return;
         }
     }
diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index e93bed020f..6db2c49677 100644
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -174,9 +174,9 @@ static void virtio_rng_set_status(VirtIODevice *vdev, 
uint8_t status)
 
 static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtIORNG *vrng = VIRTIO_RNG(dev);
-    Error *local_err = NULL;
 
     if (vrng->conf.period_ms <= 0) {
         error_setg(errp, "'period' parameter expects a positive integer");
@@ -195,9 +195,8 @@ static void virtio_rng_device_realize(DeviceState *dev, 
Error **errp)
         Object *default_backend = object_new(TYPE_RNG_BUILTIN);
 
         user_creatable_complete(USER_CREATABLE(default_backend),
-                                &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+                                errp);
+        if (*errp) {
             object_unref(default_backend);
             return;
         }
-- 
2.21.0