linux-kernel - Re: [PATCH v3 1/3] resource: Add @flags to region

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Date:	Tue, 1 Dec 2015 14:50:01 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Toshi Kani <toshi.kani@....com>
Cc:	akpm@...ux-foundation.org, rjw@...ysocki.net,
	dan.j.williams@...el.com, tony.luck@...el.com,
	vishal.l.verma@...el.com, linux-mm@...ck.org,
	linux-nvdimm@...ts.01.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/3] resource: Add @flags to region_intersects()

On Tue, Nov 24, 2015 at 03:33:36PM -0700, Toshi Kani wrote:
> region_intersects() checks if a specified region partially overlaps
> or fully eclipses a resource identified by @name.  It currently sets
> resource flags statically, which prevents the caller from specifying
> a non-RAM region, such as persistent memory.  Add @flags so that
> any region can be specified to the function.
> 
> A helper function, region_intersects_ram(), is added so that the
> callers that check a RAM region do not have to specify its iomem
> resource name and flags.  This interface is exported for modules,
> such as the EINJ driver.
> 
> Signed-off-by: Toshi Kani <toshi.kani@....com>
> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Vishal Verma <vishal.l.verma@...el.com>
> ---
>  include/linux/mm.h |    4 +++-
>  kernel/memremap.c  |    5 ++---
>  kernel/resource.c  |   23 ++++++++++++++++-------
>  3 files changed, 21 insertions(+), 11 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 00bad77..c776af3 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -362,7 +362,9 @@ enum {
>  	REGION_MIXED,
>  };
>  
> -int region_intersects(resource_size_t offset, size_t size, const char *type);
> +int region_intersects(resource_size_t offset, size_t size, const char *type,
> +			unsigned long flags);
> +int region_intersects_ram(resource_size_t offset, size_t size);
>  
>  /* Support for virtually mapped pages */
>  struct page *vmalloc_to_page(const void *addr);
> diff --git a/kernel/memremap.c b/kernel/memremap.c
> index 7658d32..98f52f1 100644
> --- a/kernel/memremap.c
> +++ b/kernel/memremap.c
> @@ -57,7 +57,7 @@ static void *try_ram_remap(resource_size_t offset, size_t size)
>   */
>  void *memremap(resource_size_t offset, size_t size, unsigned long flags)
>  {
> -	int is_ram = region_intersects(offset, size, "System RAM");

Ok, question: why do those resource things types gets identified with
a string?! We have here "System RAM" and next patch adds "Persistent
Memory".

And "persistent memory" or "System RaM" won't work and this is just
silly.

Couldn't struct resource have gained some typedef flags instead which we
can much easily test? Using the strings looks really yucky.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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