error: Fix use of error_prepend() with &error_fatal, &error_abort
From include/qapi/error.h:
* Pass an existing error to the caller with the message modified:
* error_propagate(errp, err);
* error_prepend(errp, "Could not frobnicate '%s': ", name);
Fei Li pointed out that doing error_propagate() first doesn't work
well when @errp is &error_fatal or &error_abort: the error_prepend()
is never reached.
Since I doubt fixing the documentation will stop people from getting
it wrong, introduce error_propagate_prepend(), in the hope that it
lures people away from using its constituents in the wrong order.
Update the instructions in error.h accordingly.
Convert existing error_prepend() next to error_propagate to
error_propagate_prepend(). If any of these get reached with
&error_fatal or &error_abort, the error messages improve. I didn't
check whether that's the case anywhere.
Cc: Fei Li <fli@suse.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20181017082702.5581-2-armbru@redhat.com>
diff --git a/block.c b/block.c
index 7710b39..5d51419 100644
--- a/block.c
+++ b/block.c
@@ -4697,9 +4697,9 @@
assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
if (!QLIST_EMPTY(&bs->op_blockers[op])) {
blocker = QLIST_FIRST(&bs->op_blockers[op]);
- error_propagate(errp, error_copy(blocker->reason));
- error_prepend(errp, "Node '%s' is busy: ",
- bdrv_get_device_or_node_name(bs));
+ error_propagate_prepend(errp, error_copy(blocker->reason),
+ "Node '%s' is busy: ",
+ bdrv_get_device_or_node_name(bs));
return true;
}
return false;
