On Tue, Jul 28, 2020 at 11:07:26AM +0200, Greg Kurz wrote: > On Tue, 28 Jul 2020 09:26:08 +0200 > Markus Armbruster <arm...@redhat.com> wrote: > > > Greg Kurz <gr...@kaod.org> writes: > > > > > On Mon, 20 Jul 2020 17:24:35 +0200 > > > Markus Armbruster <arm...@redhat.com> wrote: > > > > > >> Greg Kurz <gr...@kaod.org> writes: > > >> > > >> > We have a dedicated error API for hints. Use it instead of embedding > > >> > the hint in the error message, as recommanded in the "qapi/error.h" > > >> > header file. > > >> > > > >> > Since spapr_caps_apply() passes &error_fatal, all functions must > > >> > also call the ERRP_GUARD() macro for error_append_hint() to be > > >> > functional. > > >> > > >> This isn't a request for change in this patch, just an attempt to squash > > >> possible misunderstandings. > > >> > > >> It's true that error_append_hint() without ERRP_GUARD() works as long as > > >> the caller doesn't pass certain errp arguments. But the callee should > > >> work for all possible @errp arguments, not just the ones that get passed > > >> today. That's why error.h wants you to guard *all* uses of > > >> error_append_hint(errp): > > >> > > >> * = Why, when and how to use ERRP_GUARD() = > > >> * > > >> * Without ERRP_GUARD(), use of the @errp parameter is restricted: > > >> * - It must not be dereferenced, because it may be null. > > >> * - It should not be passed to error_prepend() or > > >> * error_append_hint(), because that doesn't work with &error_fatal. > > >> * ERRP_GUARD() lifts these restrictions. > > >> > > > > > > Yeah, I just wanted to emphasize that we were precisely in the case > > > where we _really_ need to lift the restriction, but I'm perfectly fine > > > with dropping this sentence if you consider it useless. > > > > I lean towards dropping it. > > > > David, > > Do you want me to send an updated version of this patch or can you > fix this in your tree ?
Updated version please, I'm afraid I've lost track of quite what was
suggested in this thread.
>
> > > BTW, should we have a way for CI to ensure that a patch that adds
> > > error_prepend(errp, ...) or error_append_hint(errp, ...) also adds
> > > ERRP_GUARD() ? Not sure that people read error.h that often...
> >
> > I don't know. Wait and see whether it's worth automating? We didn't
> > automate checking other Error API rules, like "no newlines in error
> > messages". That one can't crash, though.
> >
> > The check would have to look beyond the patch, which checkpatch.pl
> > doesn't do.
> >
>
> <thinking aloud>
> Maybe checkpatch.pl could be fed with an extended version of the patch
> that has enough context, eg. git show -U$(wc -l ${file}) ${file} ?
> </thinking aloud>
>
> > >> No need to make an argument involving the possible arguments (pardon the
> > >> pun).
> > >>
> > >
> > > :)
> > >
> > >> [...]
> > >>
> >
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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