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, 2 insertions, 3 deletions

diff --git a/hw/hyperv/vmbus.c b/hw/hyperv/vmbus.c
index a8bcb41..34392e8 100644
--- a/hw/hyperv/vmbus.c
+++ b/hw/hyperv/vmbus.c
@@ -1459,8 +1459,8 @@ static void create_channels(VMBus *vmbus, VMBusDevice *dev, Error **errp)
 
     dev->num_channels = vdc->num_channels ? vdc->num_channels(dev) : 1;
     if (dev->num_channels < 1) {
-        error_setg(&err, "invalid #channels: %u", dev->num_channels);
-        goto error_out;
+        error_setg(errp, "invalid #channels: %u", dev->num_channels);
+        return;
     }
 
     dev->channels = g_new0(VMBusChannel, dev->num_channels);
@@ -1477,7 +1477,6 @@ err_init:
     while (i--) {
         deinit_channel(&dev->channels[i]);
     }
-error_out:
     error_propagate(errp, err);
 }