Re: [PATCH v4 1/4] genirq: define an empty function set_handle_irq() if !GENERIC_IRQ_MULTI_HANDLER

["Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>]

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 */
>