Re: [PATCH v3 03/11] mm/ioremap: change the return value of io[re|un]map_allowed and rename

Baoquan He
2022-10-10T00:25:33Z

On 10/09/22 at 07:13pm, Kefeng Wang wrote:
>
> On 2022/10/9 18:31, Baoquan He wrote:
> > Currently, hooks ioremap_allowed() and iounmap_allowed() are used to
> > check if it's qualified to do ioremap, and now this is done on ARM64.
> > However, in oder to convert more architectures to take GENERIC_IOREMAP
> > method, several more things need be done in those two hooks:
> > 1) The io address mapping need be handled specifically on architectures,
> > e.g arc, ia64, s390;
> > 2) The original physical address passed into ioremap_prot() need be
> > fixed up, e.g arc;
> > 3) The 'prot' passed into ioremap_prot() need be adjusted, e.g on arc
> > and xtensa.
> >
> > To handle these three issues,
> >
> > 1) Rename ioremap_allowed() and iounmap_allowed() to arch_ioremap()
> > and arch_iounmap() since the old name can't reflect their
> > functionality after change;
> > 2) Change the return value of arch_ioremap() so that arch can add
> > specifical io address mapping handling inside and return the maped
> > address. Now their returned value means:
> > ===
> > arch_ioremap() return a bool,
> pointer?

Right, I forgot fixing it again. Thanks.

> > - IS_ERR means return an error
> > - 0 means continue to remap
> > - a non-zero, non-IS_ERR pointer is returned directly
> > arch_iounmap() return a bool,
> > - true means continue to vunmap
> > - false means skip vunmap and return directly
> ...
> > /*
> > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> > index a68f8fbf423b..2ae16906f3be 100644
> > --- a/include/asm-generic/io.h
> > +++ b/include/asm-generic/io.h
> > @@ -1049,25 +1049,26 @@ static inline void iounmap(volatile void __iomem *addr)
> > /*
> > * Arch code can implement the following two hooks when using GENERIC_IOREMAP
> > - * ioremap_allowed() return a bool,
> > - * - true means continue to remap
> > - * - false means skip remap and return directly
> > - * iounmap_allowed() return a bool,
> > + * arch_ioremap() return a bool,
> ditto...

Will change.

> > area = get_vm_area_caller(size, VM_IOREMAP,
> > __builtin_return_address(0));
> > if (!area)
> > @@ -52,7 +57,7 @@ void iounmap(volatile void __iomem *addr)
> > {
> > void *vaddr = (void *)((unsigned long)addr & PAGE_MASK);
> > - if (!iounmap_allowed(vaddr))
> > + if (!arch_iounmap((void __iomem *)addr))
> vaddr?

No, it's intentional. Alexander suggested this, both of you discussed
this in v1, see below thread.

https://lore.kernel.org/all/Yu4mYxpV0GWRTjQp@li-4a3a4a4c-28e5-11b2-a85c-a8d192c6f089.ibm.com/T/#u

> > return;
> > if (is_vmalloc_addr(vaddr))
>