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SubjectRe: [PATCH v4 1/4] genirq: define an empty function set_handle_irq() if !GENERIC_IRQ_MULTI_HANDLER
On 2020-09-17 04:46, Leizhen (ThunderTown) wrote:
> On 2020/9/15 16:43, Zhen Lei wrote:
>> To avoid compilation error if an irqchip driver references the
>> function
>> set_handle_irq() but may not select GENERIC_IRQ_MULTI_HANDLER on some
>> systems.
>
> Hi, Marc:
> Do you agree with this method?
>
> Otherwise, I should use "#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER ...
> #endif"
> to perform the compilation isolation. This may make the code less
> beautiful.
>
>>
>> For example, the Synopsys DesignWare APB interrupt controller
>> (dw_apb_ictl) is used as the secondary interrupt controller on arc,
>> csky,
>> arm64, and most arm32 SoCs, and it's also used as the primary
>> interrupt
>> controller on Hisilicon SD5203 (an arm32 SoC). The latter need to use
>> set_handle_irq() to register the top-level IRQ handler, but this multi
>> irq handler registration mechanism is not implemented on arc system.
>>
>> The input parameter "handle_irq" maybe defined as static and only
>> set_handle_irq() references it. This will trigger "defined but not
>> used"
>> warning. So add "(void)handle_irq" to suppress it.
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>> ---
>> include/linux/irq.h | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/include/linux/irq.h b/include/linux/irq.h
>> index 1b7f4dfee35b397..0848a2aaa9b40b1 100644
>> --- a/include/linux/irq.h
>> +++ b/include/linux/irq.h
>> @@ -1252,6 +1252,8 @@ void irq_matrix_free(struct irq_matrix *m,
>> unsigned int cpu,
>> * top-level IRQ handler.
>> */
>> extern void (*handle_arch_irq)(struct pt_regs *) __ro_after_init;
>> +#else
>> +#define set_handle_irq(handle_irq) do { (void)handle_irq; } while (0)
>> #endif
>>
>> #endif /* _LINUX_IRQ_H */
>>

You shouldn't just make it a NOP. Consider adding a WARN_ON(1), so that
people can realize this cannot work without the required architecture
support.

M.
--
Jazz is not dead. It just smells funny...

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