Re: [Qemu-devel] [PATCH] nvme: Make nvme_init error handling code more readable

[Fam Zheng <famz@redhat.com>]

On Mon, 05/21 09:35, Peter Maydell wrote:
> On 21 May 2018 at 07:35, Fam Zheng <famz@redhat.com> wrote:
> > Coverity doesn't like the tests under fail label (report CID 1385847).
> > Reset the fields so the clean up order is more apparent.
> >
> > Signed-off-by: Fam Zheng <famz@redhat.com>
> > ---
> >  block/nvme.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/block/nvme.c b/block/nvme.c
> > index 6f71122bf5..8239b920c8 100644
> > --- a/block/nvme.c
> > +++ b/block/nvme.c
> > @@ -560,6 +560,13 @@ static int nvme_init(BlockDriverState *bs, const char *device, int namespace,
> >      qemu_co_queue_init(&s->dma_flush_queue);
> >      s->nsid = namespace;
> >      s->aio_context = bdrv_get_aio_context(bs);
> > +
> > +    /* Fields we've not touched should be zero-initialized by block layer
> > +     * already, but reset them anyway to make the error handling code easier to
> > +     * reason. */
> > +    s->regs = NULL;
> > +    s->vfio = NULL;
> > +
> >      ret = event_notifier_init(&s->irq_notifier, 0);
> >      if (ret) {
> >          error_setg(errp, "Failed to init event notifier");
> 
> I suspect that either coverity or some compilers will complain that
> the assignment to s->vfio here is redundant, because we'll either
> return early without looking at it, or we'll get to the assignment
>  s->vfio = qemu_vfio_open_pci(...)
> which overrides it.

Hmm, okay, the compiler wants you to be at least as smart as it is, but no
smarter! I will revise the patch.

Fam