Re: [PATCH] pci_dma_rw: return correct value instead of 0

[Emanuele Giuseppe Esposito]

On 30/07/2020 09:41, Stefano Garzarella wrote:
> On Thu, Jul 30, 2020 at 12:17:32AM +0200, Emanuele Giuseppe Esposito wrote:
> > pci_dma_rw currently always returns 0, regardless
> > of the result of dma_memory_rw. Adjusted to return
> > the correct value.
> >
> > Signed-off-by: Emanuele Giuseppe Esposito <e.emanuelegiuseppe@gmail.com>
> > ---
> >   include/hw/pci/pci.h | 3 +--
> >   1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> > index c1bf7d5356..41c4ab5932 100644
> > --- a/include/hw/pci/pci.h
> > +++ b/include/hw/pci/pci.h
> > @@ -787,8 +787,7 @@ static inline AddressSpace *pci_get_address_space(PCIDevice 
> > *dev)
> >   static inline int pci_dma_rw(PCIDevice *dev, dma_addr_t addr,
> >                                void *buf, dma_addr_t len, DMADirection dir)
> >   {
> > -    dma_memory_rw(pci_get_address_space(dev), addr, buf, len, dir);
> > -    return 0;
> > +    return dma_memory_rw(pci_get_address_space(dev), addr, buf, len, dir);
> >   }
>
> I think it's a left over from when we used "void cpu_physical_memory_rw()".
>
> I agree that it is better to return the dma_memory_rw() return value, but
> at first look, no one seems to check the return value of pci_dma_rw(),
> pci_dma_read(), andpci_dma_write().
>
> Should we make them void?

I noticed that nobody checks the return of those functions, but I think 
checking for possible error is always useful. I am using the edu device 
and clearly doing something wrong since with this fix I discovered that 
the pci_dma_read call returns nonzero.

Keeping the function as it is or void would make it harder to spot such 
errors in future.

Thank you,
Emanuele

> Anyway, for this patch:
>
> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
>
> Thanks,
> Stefano