Re: [PATCH 7/9] ppc: silence the compiler warnings

[David Gibson]

On Wed, Oct 28, 2020 at 03:42:31PM +0100, Thomas Huth wrote:
> On 28/10/2020 05.29, David Gibson wrote:
> > On Wed, Oct 28, 2020 at 12:18:17PM +0800, Chen Qun wrote:
> >> When using -Wimplicit-fallthrough in our CFLAGS, the compiler showed 
> >> warning:
> >> hw/ppc/ppc.c: In function ‘ppc6xx_set_irq’:
> >> hw/ppc/ppc.c:118:16: warning: this statement may fall through 
> >> [-Wimplicit-fallthrough=]
> >>   118 |             if (level) {
> >>       |                ^
> >> hw/ppc/ppc.c:123:9: note: here
> >>   123 |         case PPC6xx_INPUT_INT:
> >>       |         ^~~~
> >>
> >> Add the corresponding "fall through" comment to fix it.
> >>
> >> Reported-by: Euler Robot <euler.robot@huawei.com>
> >> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
> > 
> > Acked-by: David Gibson <david@gibson.dropbear.id.au>
> > 
> >> ---
> >> Cc: David Gibson <david@gibson.dropbear.id.au>
> >> ---
> >>  hw/ppc/ppc.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> >> index 4a11fb1640..f9eb8f21b4 100644
> >> --- a/hw/ppc/ppc.c
> >> +++ b/hw/ppc/ppc.c
> >> @@ -120,6 +120,7 @@ static void ppc6xx_set_irq(void *opaque, int pin, int 
> >> level)
> >>              } else {
> >>                  cpu_ppc_tb_stop(env);
> >>              }
> >> +            /* fall through */
> >>          case PPC6xx_INPUT_INT:
> >>              /* Level sensitive - active high */
> >>              LOG_IRQ("%s: set the external IRQ state to %d\n",
> > 
> 
> Is that fall through actually really the right thing to do here? I'd rather
> expect to see a PPC_INTERRUPT_DECR instead of a PPC_INTERRUPT_EXT in case
> someone messes with the TBEN pin? So I assume this is likely rather bug and
> we should a "break" statement here instead?

Oh.. good catch, I think I misread this.  I thought the change was
correct, because DECRs look somewhat like external interrupts.  But
this is TBEN, not a DECR interrupt per se.  So, yes, I think this was
a bug and it should be a break instead.

-- 
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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