Re: About the code updte of the arc/linux/arch/beta/kernel/irq_64.c

Re: About the code updte of the arc/linux/arch/beta/kernel/irq_64.c

[Christophe Leroy]

Hi Xia,

Le 01/05/2024 à 08:22, 赵夏 a écrit :
> Hi Christophe,
> 
>    I identified that the function named "arch_local_irq_restore" of the 
> file irq_64.c was updated by you frequently in the last two years.

You mean arch/powerpc/kernel/irq_64.c I guess ?

I don't think I "frequently" changed it. What I did was mainly 
maintenance, I first extracted all 64 bits code from irq.c into irq_64.c 
to ease maintenance, then I did a few cosmetic changes with no 
functionnal impacts.

As far as I can see some more important changes were done by Nick, maybe 
I'll be able to answer you better. I am myself not a PPC64 expert, my 
domain in mainly PPC32.

>    In the previous code version (such as Linux Kernel 5.10.7), I thought 
> that an interruption such as doorbell might happen before 
> "local_paca->irq_happened = 0;"  which can cause a problem. Is this the 
> correct understanding? I have two questions.
> 
>    1. If the previous version can cause the problem, can the current fix 
> solve the problem?
>    2. If we do not care about the os performance, can we close the 
> nested interrupt mechanism to avoid the problem? If we can, how to close 
> the nested interrupt?
> 
> Kind regards
> Xia


Thanks
Christophe