On Sat, Aug 20, 2022 at 08:31:15AM +0800, Baoquan He wrote: Hi Baoquan, > arch_ioremap() return a bool, > - IS_ERR means return an error > - NULL means continue to remap > - a non-NULL, non-IS_ERR pointer is returned directly > arch_iounmap() return a bool, > - 0 means continue to vunmap > - error code means skip vunmap and return directly It would make more sense if the return values were described from the prospective of an architecture, not the caller. I.e true - unmapped, false - not supported, etc. > diff --git a/mm/ioremap.c b/mm/ioremap.c > index 8652426282cc..99fde69becc7 100644 > --- a/mm/ioremap.c > +++ b/mm/ioremap.c > @@ -17,6 +17,13 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size, > unsigned long offset, vaddr; > phys_addr_t last_addr; > struct vm_struct *area; > + void __iomem *ioaddr; > + > + ioaddr = arch_ioremap(phys_addr, size, prot); > + if (IS_ERR(ioaddr)) > + return NULL; > + else if (ioaddr) > + return ioaddr; It seems to me arch_ioremap() could simply return an address or an error. Then IOMEM_ERR_PTR(-ENOSYS) if the architecture does not support it reads much better than the cryptic NULL. Probably arch_iounmap() returning error would look better too, though not sure about that. Thanks!
