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

From: Kefeng Wang
Date: Sun Oct 09 2022 - 21:05:35 EST

On 2022/10/10 8:25, Baoquan He wrote:
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,
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,
Will change.

area = get_vm_area_caller(size, VM_IOREMAP,
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))
No, it's intentional. Alexander suggested this, both of you discussed
this in v1, see below thread.
ok, please ignore it.

if (is_vmalloc_addr(vaddr))