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SubjectRe: [PATCH] irqchip/gic: check return value of of_address_to_resource
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Marc,

I'm also wondering if of_address_to_resource can really fail in this
particular case?

What if we just explicitly discard the return value like this:

(void)of_address_to_resource(node, 1, &cpuif_res);

This suppresses Coverity warning by explicitly stating we are 100% sure
the function call will always return success.

On 07/05/2018 12:13 PM, Marc Zyngier wrote:
> Hi Bo,
>
> On Thu, 5 Jul 2018 11:20:59 -0700
> Bo Yan <byan@nvidia.com> wrote:
>
>> The of_address_to_resource returns 0 if successful. gic_check_eoimode
>> calls it without checking the return value. This induces Coverity
>> warning: "Unchecked return value".
>>
>> Return false from gic_check_eoimode if of_address_to_resource returns
>> non-0 value.
>>
>> Signed-off-by: Bo Yan <byan@nvidia.com>
>> ---
>> drivers/irqchip/irq-gic.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
>> index ced10c4..0bceb10 100644
>> --- a/drivers/irqchip/irq-gic.c
>> +++ b/drivers/irqchip/irq-gic.c
>> @@ -1284,7 +1284,8 @@ static bool gic_check_eoimode(struct device_node *node, void __iomem **base)
>> {
>> struct resource cpuif_res;
>>
>> - of_address_to_resource(node, 1, &cpuif_res);
>> + if (of_address_to_resource(node, 1, &cpuif_res))
>> + return false;
>
> We've just done an of_iomap() on this resource, which succeeded. How
> can the same thing now fail? It would mean that the device tree has
> been pulled from under our feet...
>
> And if it could happen, why is returning false the right thing to do?
> Why would we say we want EOImode==0 instead of 1?
>
>>
>> if (!is_hyp_mode_available())
>> return false;
>
> As it stands, I'm not taking such a patch. It either papers over a
> bigger problem, or just keeps a warning quiet for the sake of it.
>
> Thanks,
>
> M.
>

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