Re: [PATCH] 9pfs: Fix some return statements in the synth backend

[Greg Kurz <groug@kaod.org>]

On Mon, 28 Nov 2022 08:35:22 +0100
Markus Armbruster <armbru@redhat.com> wrote:

> Greg Kurz <groug@kaod.org> writes:
> 
> > The qemu_v9fs_synth_mkdir() and qemu_v9fs_synth_add_file() functions
> > currently return a positive errno value on failure. This causes
> > checkpatch.pl to spit several errors like the one below:
> >
> > ERROR: return of an errno should typically be -ve (return -EAGAIN)
> > #79: FILE: hw/9pfs/9p-synth.c:79:
> > +        return EAGAIN;
> >
> > Simply change the sign. This has no consequence since callers
> > assert() the returned value to be equal to 0.
> 
> Out of curiosity: why is assert() appropriate?
> 

Most of the code base comes from the original synth backend which
was designed to expose QEMU internals to the guest using 9p. The
hope of the virtio-9p authors was that each QEMU subsystem would
create its own tree using these two functions (note that they
are declared extern). Of course these never happened and the synth
backend remained nearly dead code for years, until finally it got
re-used to implement 9p qtest. In this context, failure to create a
synthetic directory or file means the related test has a bug (e.g.
messing with the paths used by some other test). This code likely
needs improvements but we never got to it.

> > While here also get rid of the uneeded ret variables as suggested
> > by return_directly.cocci.
> >
> > Reported-by: Markus Armbruster <armbru@redhat.com>
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>