On Tue, 2010-08-17 at 08:56 +0800, Jin Dongming wrote:
> acpi_pre_map() is used for remapping the physical address of I/O, so
> it should be return NULL or remapped virtual address. The problem
> is whether I/O remapping is successful or not, the function returns
> NULL always.
No. NULL is returned for error path only. Please check the code again.
> In acpi_pre_map(), after the physical address is remapped sucessfully,
> it will check whether the physical address has been added into acpi_iomaps
> list again. If the physical address has beed added into acpi_iomaps,
> the virtual address will be saved in vaddr. Otherwise, NULL be saved in
> vaddr.
>
> So if the physical address has never been remapped, the return value of
> acpi_pre_map will be NULL always.
>
> This patch fixed it and I confirmed it on x86_64 next-tree.
>
> Signed-off-by: Jin Dongming <jin.dongming@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/acpi/atomicio.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/atomicio.c b/drivers/acpi/atomicio.c
> index 8f8bd73..1bc2614 100644
> --- a/drivers/acpi/atomicio.c
> +++ b/drivers/acpi/atomicio.c
> @@ -133,7 +133,7 @@ static void __iomem *acpi_pre_map(phys_addr_t paddr,
>
> spin_lock_irqsave(&acpi_iomaps_lock, flags);
> vaddr = __acpi_try_ioremap(paddr, size);
> - if (vaddr) {
> + if (unlikely(vaddr)) {
pre_map is not performance critical, so "unlikely" here helps little.
> spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
> iounmap(map->vaddr);
> kfree(map);
> @@ -142,7 +142,7 @@ static void __iomem *acpi_pre_map(phys_addr_t paddr,
> list_add_tail_rcu(&map->list, &acpi_iomaps);
> spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
>
> - return vaddr + (paddr - pg_off);
> + return map->vaddr + (paddr - pg_off);
> err_unmap:
> iounmap(vaddr);
> return NULL;
When will vaddr != map->vaddr?
Best Regards,
Huang Ying
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