[v1] silence the compiler warnings

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

Posted by Chen Qun 5 years, 3 months ago

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>
---
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",
-- 
2.27.0

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

Posted by David Gibson 5 years, 3 months ago

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",

-- 
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

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

Posted by Thomas Huth 5 years, 3 months ago

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?

 Thomas

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

Posted by David Gibson 5 years, 3 months ago

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

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

Posted by Chenqun (kuhn) 5 years, 3 months ago

> -----Original Message-----
> From: David Gibson [mailto:david@gibson.dropbear.id.au]
> Sent: Thursday, October 29, 2020 7:39 AM
> To: Thomas Huth <thuth@redhat.com>
> Cc: Chenqun (kuhn) <kuhn.chenqun@huawei.com>; qemu-trivial@nongnu.org;
> Euler Robot <euler.robot@huawei.com>; qemu-devel@nongnu.org; ganqixin
> <ganqixin@huawei.com>; Zhanghailiang <zhang.zhanghailiang@huawei.com>;
> qemu-ppc@nongnu.org
> Subject: Re: [PATCH 7/9] ppc: silence the compiler warnings
> 
> 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.
> 
This bug looks like it's been hidden for years. Thanks for your point.
According to your opinion, I will modify it in the next version.

Thanks,
Chen Qun
> --
> 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