error: Avoid unnecessary error_propagate() after error_setg()

Replace

    error_setg(&err, ...);
    error_propagate(errp, err);

by

    error_setg(errp, ...);

Related pattern:

    if (...) {
        error_setg(&err, ...);
        goto out;
    }
    ...
 out:
    error_propagate(errp, err);
    return;

When all paths to label out are that way, replace by

    if (...) {
        error_setg(errp, ...);
        return;
    }

and delete the label along with the error_propagate().

When we have at most one other path that actually needs to propagate,
and maybe one at the end that where propagation is unnecessary, e.g.

    foo(..., &err);
    if (err) {
        goto out;
    }
    ...
    bar(..., &err);
 out:
    error_propagate(errp, err);
    return;

move the error_propagate() to where it's needed, like

    if (...) {
        foo(..., &err);
        error_propagate(errp, err);
        return;
    }
    ...
    bar(..., errp);
    return;

and transform the error_setg() as above.

In some places, the transformation results in obviously unnecessary
error_propagate().  The next few commits will eliminate them.

Bonus: the elimination of gotos will make later patches in this series
easier to review.

Candidates for conversion tracked down with this Coccinelle script:

    @@
    identifier err, errp;
    expression list args;
    @@
    -    error_setg(&err, args);
    +    error_setg(errp, args);
         ... when != err
         error_propagate(errp, err);

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-34-armbru@redhat.com>

1 files changed, 9 insertions, 13 deletions

diff --git a/block/throttle-groups.c b/block/throttle-groups.c
index e411051160..3d7e7cf990 100644
--- a/block/throttle-groups.c
+++ b/block/throttle-groups.c
@@ -819,16 +819,17 @@ static void throttle_group_set(Object *obj, Visitor *v, const char * name,
      * transaction, as certain combinations are invalid.
      */
     if (tg->is_initialized) {
-        error_setg(&local_err, "Property cannot be set after initialization");
-        goto ret;
+        error_setg(errp, "Property cannot be set after initialization");
+        return;
     }
 
     if (!visit_type_int64(v, name, &value, &local_err)) {
-        goto ret;
+        error_propagate(errp, local_err);
+        return;
     }
     if (value < 0) {
-        error_setg(&local_err, "Property values cannot be negative");
-        goto ret;
+        error_setg(errp, "Property values cannot be negative");
+        return;
     }
 
     cfg = &tg->ts.cfg;
@@ -841,9 +842,9 @@ static void throttle_group_set(Object *obj, Visitor *v, const char * name,
         break;
     case BURST_LENGTH:
         if (value > UINT_MAX) {
-            error_setg(&local_err, "%s value must be in the"
-                       "range [0, %u]", info->name, UINT_MAX);
-            goto ret;
+            error_setg(errp, "%s value must be in the" "range [0, %u]",
+                       info->name, UINT_MAX);
+            return;
         }
         cfg->buckets[info->type].burst_length = value;
         break;
@@ -851,11 +852,6 @@ static void throttle_group_set(Object *obj, Visitor *v, const char * name,
         cfg->op_size = value;
         break;
     }
-
-ret:
-    error_propagate(errp, local_err);
-    return;
-
 }
 
 static void throttle_group_get(Object *obj, Visitor *v, const char *name,