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, 6 insertions, 13 deletions

diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
index 320dffbaa9..a44f5a61ac 100644
--- a/backends/hostmem-file.c
+++ b/backends/hostmem-file.c
@@ -114,18 +114,16 @@ static void file_memory_backend_set_align(Object *o, Visitor *v,
     uint64_t val;
 
     if (host_memory_backend_mr_inited(backend)) {
-        error_setg(&local_err, "cannot change property '%s' of %s",
-                   name, object_get_typename(o));
-        goto out;
+        error_setg(errp, "cannot change property '%s' of %s", name,
+                   object_get_typename(o));
+        return;
     }
 
     if (!visit_type_size(v, name, &val, &local_err)) {
-        goto out;
+        error_propagate(errp, local_err);
+        return;
     }
     fb->align = val;
-
- out:
-    error_propagate(errp, local_err);
 }
 
 static bool file_memory_backend_get_pmem(Object *o, Error **errp)
@@ -139,7 +137,6 @@ static void file_memory_backend_set_pmem(Object *o, bool value, Error **errp)
     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
 
     if (host_memory_backend_mr_inited(backend)) {
-
         error_setg(errp, "cannot change property 'pmem' of %s.",
                    object_get_typename(o));
         return;
@@ -147,13 +144,9 @@ static void file_memory_backend_set_pmem(Object *o, bool value, Error **errp)
 
 #ifndef CONFIG_LIBPMEM
     if (value) {
-        Error *local_err = NULL;
-
-        error_setg(&local_err,
-                   "Lack of libpmem support while setting the 'pmem=on'"
+        error_setg(errp, "Lack of libpmem support while setting the 'pmem=on'"
                    " of %s. We can't ensure data persistence.",
                    object_get_typename(o));
-        error_propagate(errp, local_err);
         return;
     }
 #endif