linux-kernel - RE: [PATCH v3 1/5] ACPI: change __init to __ref for early_acpi_os_unmap

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Message-ID: <1AE640813FDE7649BE1B193DEA596E883BB4BDBB@SHSMSX101.ccr.corp.intel.com>
Date:	Wed, 17 Feb 2016 02:44:42 +0000
From:	"Zheng, Lv" <lv.zheng@...el.com>
To:	Aleksey Makarov <aleksey.makarov@...aro.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>
CC:	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Russell King <linux@....linux.org.uk>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	Leif Lindholm <leif.lindholm@...aro.org>,
	Graeme Gregory <graeme.gregory@...aro.org>,
	"Al Stone" <ahs3@...hat.com>,
	Christopher Covington <cov@...eaurora.org>,
	"Len Brown" <lenb@...nel.org>
Subject: RE: [PATCH v3 1/5] ACPI: change __init to __ref for
 early_acpi_os_unmap_memory()

Hi,

> -----Original Message-----
> From: linux-acpi-owner@...r.kernel.org [mailto:linux-acpi-
> owner@...r.kernel.org] On Behalf Of Aleksey Makarov
> Sent: Tuesday, February 16, 2016 2:05 AM
> To: linux-acpi@...r.kernel.org
> Cc: linux-serial@...r.kernel.org; linux-kernel@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; Aleksey Makarov <aleksey.makarov@...aro.org>;
> Russell King <linux@....linux.org.uk>; Greg Kroah-Hartman
> <gregkh@...uxfoundation.org>; Rafael J . Wysocki <rjw@...ysocki.net>; Leif
> Lindholm <leif.lindholm@...aro.org>; Graeme Gregory
> <graeme.gregory@...aro.org>; Al Stone <ahs3@...hat.com>; Christopher
> Covington <cov@...eaurora.org>; Len Brown <lenb@...nel.org>
> 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

> 
> Signed-off-by: Aleksey Makarov <aleksey.makarov@...aro.org>
> ---
>  drivers/acpi/osl.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> index 67da6fb..8a552cd 100644
> --- a/drivers/acpi/osl.c
> +++ b/drivers/acpi/osl.c
> @@ -497,7 +497,11 @@ void __ref acpi_os_unmap_memory(void *virt,
> acpi_size size)
>  }
>  EXPORT_SYMBOL_GPL(acpi_os_unmap_memory);
> 
> -void __init early_acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
> +/*
> + * acpi_gbl_permanent_mmap is set in __init acpi_early_init()
> + * so it is safe to call early_acpi_os_unmap_memory() from anywhere
> + */
> +void __ref early_acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
>  {
>  	if (!acpi_gbl_permanent_mmap)
>  		__acpi_unmap_table(virt, size);
> --
> 2.7.1
> 
> --
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