Re: [Qemu-devel] [PATCH v3 5/7] pci: Make errp the last parameter of pci_add_capability()

[Mao Zhongyi]

Hi, Markus

On 06/07/2017 03:05 PM, Markus Armbruster wrote:
> Mao Zhongyi <address@hidden> writes:
>
> > Hi, Eduardo
> >
> > On 06/06/2017 10:52 PM, Eduardo Habkost wrote:
> > > On Tue, Jun 06, 2017 at 07:26:30PM +0800, Mao Zhongyi wrote:
> > > > Add Error argument for pci_add_capability() to leverage the errp
> > > > to pass info on errors. This way is helpful for its callers to
> > > > make a better error handling when moving to 'realize'.
> [...]
> > > > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > > > index b73bfea..2bba37a 100644
> > > > --- a/hw/pci/pci.c
> > > > +++ b/hw/pci/pci.c
> > > > @@ -2264,15 +2264,13 @@ static void pci_del_option_rom(PCIDevice *pdev)
> > > >   * in pci config space
> > > >   */
> > > >  int pci_add_capability(PCIDevice *pdev, uint8_t cap_id,
> > > > -                       uint8_t offset, uint8_t size)
> > > > +                       uint8_t offset, uint8_t size,
> > > > +                       Error **errp)
> > > >  {
> > > >      int ret;
> > > > -    Error *local_err = NULL;
> > > >
> > > > -    ret = pci_add_capability2(pdev, cap_id, offset, size, &local_err);
> > > > -    if (ret < 0) {
> > > > -        error_report_err(local_err);
> > > > -    }
> > > > +    ret = pci_add_capability2(pdev, cap_id, offset, size, errp);
> > > > +
> > > >      return ret;
> > > >  }
> > >
> > > pci_add_capability() and pci_add_capability2() now do exactly the
> > > same, why are both being kept?  I suggest replacing
> > > pci_add_capability2() with pci_add_capability() everywhere (on a
> > > separate patch).
> >
> > Completely remove pci_add_capability and direct use pci_add_capability2()
> > everywhere is it a more thorough way?
>
> You're converting pci_add_capability() to Error because you need the
> Error for your conversions to realize().

it's true.

> I recommend to change the calls where you need the Error (and only
> these) to call pci_add_capability2() instead.
>
> When no calls to pci_add_capability() remain, we remove it.  If that
> becomes the case in your series, you remove it.
>
> Okay?

This is a gentle way of doing it. After read the code I found only
parts need to be replaced by pci_add_capability2() in my series as
follow your advice, this is no problem. But it means that the remaining
replacement will be reworked in the future, although it can be fixed
absolutely in a separate patch now. Of course, this is just my own
opinion, consider the reason for git history I would rather hear your
advice. :)

Thanks
Mao