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, 4 insertions, 6 deletions

diff --git a/net/filter-buffer.c b/net/filter-buffer.c
index 8e42934b37..143627fcaf 100644
--- a/net/filter-buffer.c
+++ b/net/filter-buffer.c
@@ -174,17 +174,15 @@ static void filter_buffer_set_interval(Object *obj, Visitor *v,
     uint32_t value;
 
     if (!visit_type_uint32(v, name, &value, &local_err)) {
-        goto out;
+        error_propagate(errp, local_err);
+        return;
     }
     if (!value) {
-        error_setg(&local_err, "Property '%s.%s' requires a positive value",
+        error_setg(errp, "Property '%s.%s' requires a positive value",
                    object_get_typename(obj), name);
-        goto out;
+        return;
     }
     s->interval = value;
-
-out:
-    error_propagate(errp, local_err);
 }
 
 static void filter_buffer_init(Object *obj)