Re: [XEN][RFC PATCH v4 10/16] asm/smp.h: move cpu related function to asm/cpu.h

[Julien Grall <julien@xxxxxxx>]

Hi Vikram,

On 07/12/2022 06:18, Vikram Garhwal wrote:
> Dynamic programming ops will modify the dt_host and there might be other
> function which are browsing the dt_host at the same time. To avoid the race
> conditions, adding rwlock for browsing the dt_host. But adding rwlock in
> device_tree.h causes following circular dependency:
>      device_tree.h->rwlock.h->smp.h->asm/smp.h->device_tree.h
>
> Inside arch/arm/include/asm/smp.h, there is one function which needs
> device_tree.h, moved the cpu related function to a new file:
> arch/arm/include/asm/cpu.h
Given there is only one function, I don't really see the benefits of 
splitting smp.h and then adding #ifdef CONFIG_ARM in the common code.
Instead, it would be better if we don't include device_tree.h in the 
header but in the c files that need to call arch_cpu_init() and forward 
declare dt_device_node.
Another potential approach is to move out the percpu_rwlock helpers in a 
separate header. The advantage with this approach is we would reduce the 
number of definition included everywhere (there are not many use of the 
percpu rwlock).
Cheers,

--
Julien Grall