Hi,

-----Original Message-----
From: linux-acpi-owner at vger.kernel.org [mailto:linux-acpi-
owner at vger.kernel.org] On Behalf Of Aleksey Makarov
Sent: Tuesday, February 16, 2016 2:05 AM
To: linux-acpi at vger.kernel.org
Cc: linux-serial at vger.kernel.org; linux-kernel at vger.kernel.org; linux-arm-
kernel at lists.infradead.org; Aleksey Makarov [off-list ref];
Russell King [off-list ref]; Greg Kroah-Hartman
[off-list ref]; Rafael J . Wysocki [off-list ref]; Leif
Lindholm [off-list ref]; Graeme Gregory
[off-list ref]; Al Stone [off-list ref]; Christopher
Covington [off-list ref]; Len Brown [off-list ref]
Subject: [PATCH v3 1/5] ACPI: change __init to __ref for
early_acpi_os_unmap_memory()

early_acpi_os_unmap_memory() is marked as __init because it calls
__acpi_unmap_table(), but only when acpi_gbl_permanent_mmap is not set.

acpi_gbl_permanent_mmap is set in __init acpi_early_init()
so it is safe to call early_acpi_os_unmap_memory() from anywhere

We need this function to be non-__init because we need access to
some tables at unpredictable time--it may be before or after
acpi_gbl_permanent_mmap is set.  For example, SPCR (Serial Port Console
Redirection) table is needed each time a new console is registered.
It can be quite early (console_initcall) or when a module is inserted.
When this table accessed before acpi_gbl_permanent_mmap is set,
the pointer should be unmapped.  This is exactly what this function
does.

[Lv Zheng] 
Why don't you use another API instead of early_acpi_os_unmap_memory() in case you want to unmap things in any cases.
acpi_os_unmap_memory() should be the one to match this purpose.
It checks acpi_gbl_ppermanent_mmap in acpi_os_unmap_iomem().
And in fact early_acpi_os_unmap_memory() should be removed.

Thanks and best regards
-Lv