Re: [Qemu-devel] [PATCH v6 3/5] qobject: replace qobject_incref/QINCREF qobject_decref/QDECREF

[Markus Armbruster <armbru@redhat.com>]

Eric Blake <eblake@redhat.com> writes:

> On 04/19/2018 10:01 AM, Marc-André Lureau wrote:
>> Now that we can safely call QOBJECT() on QObject * as well as its
>> subtypes, we can have macros qobject_ref() / qobject_unref() that work
>> everywhere instead of having to use QINCREF() / QDECREF() for QObject
>> and qobject_incref() / qobject_decref() for its subtypes.
>> 
>> Note that the new macros evaluate their argument exactly once, thus no
>> need to shout them.
>
> It's still useful information to include in the commit message that you
> did the substitution by sed, then fixed up compiler warnings that
> resulted from the new macro implementation being slightly more
> type-safe, as well as fixing up a long line.  That way, if someone
> backports this patch, they know how to resolve conflicts and/or check
> that they are not missing a conversion.

What about inserting

   The replacement is mechanical, except I broke a long line, and added
   a cast in monitor_qmp_cleanup_req_queue_locked().  Unlike
   qobject_decref(), qobject_unref() doesn't accept void *.

The justification sounds awkward because it is.  qobject_unref() turns
out to be less function-like than it looks on first glance.  The actual
culprit is QOBJECT().

> Writing good commit messages is an art form - but in general, if
> something was questioned during review of a previous revision, then it's
> never a bad idea to beef up the commit message to answer that question
> in advance for the next reviewer.
>
>> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
>> Reviewed-by: Eric Blake <eblake@redhat.com>