[PATCH] powerpc/64: Include cache.h directly in paca.h

[Michael Ellerman]

Christophe Leroy <christophe.leroy at csgroup.eu> writes:
> Le 27/05/2022 à 13:20, Michael Ellerman a écrit :
>> paca.h uses ____cacheline_aligned without directly including cache.h,
>> where it's defined.
>> 
>> For Book3S builds that's OK because paca.h includes lppaca.h, and it
>> does include cache.h.
>> 
>> But Book3E builds have been getting cache.h indirectly via printk.h,
>> which is dicey, and in fact that include was recently removed, leading
>> to build errors such as:
>> 
>>    ld: fs/isofs/dir.o:(.bss+0x0): multiple definition of `____cacheline_aligned'; fs/isofs/namei.o:(.bss+0x0): first defined here
>> 
>> So include cache.h directly to fix the build error.
>> 
>> Fixes: 534aa1dc975a ("printk: stop including cache.h from printk.h")
>> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
>
> You've got other candidates for the fix:
>
> $ git grep -L linux/cache.h `git grep -l ____cacheline_aligned 
> arch/powerpc`
> arch/powerpc/include/asm/hardirq.h
> arch/powerpc/include/asm/iommu.h
> arch/powerpc/include/asm/paca.h
> arch/powerpc/include/asm/processor.h
> arch/powerpc/kernel/prom_init.c
>
> Discussion at 
> https://lore.kernel.org/lkml/e3c8b2bf-b55d-4c2c-a1cf-d5e9941e26b0@csgroup.eu/t/

Adding it to paca.h seems to also fix those build errors, so I'll leave
it at that for now.

Adding cache.h to those other headers should be fine, but I don't want
to do it just before sending my pull request, because changing include
order can easily cause bugs, and they're not always easy to find.

cheers