error: Use error_prepend() where it makes obvious sense

Done with this Coccinelle semantic patch

    @@
    expression FMT, E1, E2;
    expression list ARGS;
    @@
    -    error_setg(E1, FMT, ARGS, error_get_pretty(E2));
    +    error_propagate(E1, E2);/*###*/
    +    error_prepend(E1, FMT/*@@@*/, ARGS);

followed by manual cleanup, first because I can't figure out how to
make Coccinelle transform strings, and second to get rid of now
superfluous error_propagate().

We now use or propagate the original error whole instead of just its
message obtained with error_get_pretty().  This avoids suppressing its
hint (see commit 50b7b00), but I can't see how the errors touched in
this commit could come with hints.  It also improves the message
printed with &error_abort when we screw up (see commit 1e9b65b).

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

1 files changed, 2 insertions, 4 deletions

diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index 00cdac6..7bc8288 100644
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -217,11 +217,9 @@ static void vhost_scsi_realize(DeviceState *dev, Error **errp)
     }
 
     if (vs->conf.vhostfd) {
-        vhostfd = monitor_fd_param(cur_mon, vs->conf.vhostfd, &err);
+        vhostfd = monitor_fd_param(cur_mon, vs->conf.vhostfd, errp);
         if (vhostfd == -1) {
-            error_setg(errp, "vhost-scsi: unable to parse vhostfd: %s",
-                       error_get_pretty(err));
-            error_free(err);
+            error_prepend(errp, "vhost-scsi: unable to parse vhostfd: ");
             return;
         }
     } else {