linux-kernel - Re: [PATCH 2/3 v4] resource: Add new flag IORESOURCE_MEM

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Date:	Tue, 24 Feb 2015 09:04:40 -0800
From:	Dan Williams <dan.j.williams@...el.com>
To:	Boaz Harrosh <boaz@...xistor.com>
Cc:	Ingo Molnar <mingo@...nel.org>, Ingo Molnar <mingo@...hat.com>,
	Andy Lutomirski <luto@...capital.net>,
	Ross Zwisler <ross.zwisler@...ux.intel.com>,
	X86 ML <x86@...nel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"Roger C. Pao" <rcpao.enmotus@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-nvdimm <linux-nvdimm@...ts.01.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Matthew Wilcox <willy@...ux.intel.com>,
	Christoph Hellwig <hch@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [PATCH 2/3 v4] resource: Add new flag IORESOURCE_MEM_WARN

On Tue, Feb 24, 2015 at 7:00 AM, Boaz Harrosh <boaz@...xistor.com> wrote:
>
> Resource providers set this flag if they want
> that request_region will print a warning in dmesg
> if this particular memory resource is locked by a driver.
>
> Thous acting as a Protocol Police about experimental
> devices that did not pass a committee approval.
>
> The Only user of  this flag is x86/kernel/e820.c that
> wants to WARN about UNKNOWN memory types.
>
> NOTE: It would be preferred if I defined a general flag say
>       IORESOURCE_WARN, where any kind of resource provider
>       can WARN on use, but we have run out of flags in the
>       32bit long systems. So I defined a free bit from the
>       resource specific flags for mem resources. This is
>       why I need to check if this is a memory resource first
>       so not to conflict with other resource specific flags.
>       (Though actually no one is using this specific bit)
>
> CC: Thomas Gleixner <tglx@...utronix.de>
> CC: Ingo Molnar <mingo@...hat.com>
> CC: "H. Peter Anvin" <hpa@...or.com>
> CC: x86@...nel.org
> CC: Dan Williams <dan.j.williams@...el.com>
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: Bjorn Helgaas <bhelgaas@...gle.com>
> CC: Vivek Goyal <vgoyal@...hat.com>
> Signed-off-by: Boaz Harrosh <boaz@...xistor.com>
> ---
>  arch/x86/kernel/e820.c | 3 +++
>  include/linux/ioport.h | 1 +
>  kernel/resource.c      | 9 ++++++++-
>  3 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index 1a8a1c3..105bb37 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -961,6 +961,9 @@ void __init e820_reserve_resources(void)
>
>                 res->flags = IORESOURCE_MEM;
>
> +               if (_is_unknown_type(e820.map[i].type))
> +                       res->flags |= IORESOURCE_MEM_WARN;
> +
>                 /*
>                  * don't register the region that could be conflicted with
>                  * pci device BAR resource and insert them later in
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 2c525022..f78972b 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -90,6 +90,7 @@ struct resource {
>  #define IORESOURCE_MEM_32BIT           (3<<3)
>  #define IORESOURCE_MEM_SHADOWABLE      (1<<5)  /* dup: IORESOURCE_SHADOWABLE */
>  #define IORESOURCE_MEM_EXPANSIONROM    (1<<6)
> +#define IORESOURCE_MEM_WARN            (1<<7)  /* WARN if requested by driver */
>
>  /* PnP I/O specific bits (IORESOURCE_BITS) */
>  #define IORESOURCE_IO_16BIT_ADDR       (1<<0)
> diff --git a/kernel/resource.c b/kernel/resource.c
> index 19f2357..4bab16f 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -1075,8 +1075,15 @@ struct resource * __request_region(struct resource *parent,
>                         break;
>                 if (conflict != parent) {
>                         parent = conflict;
> -                       if (!(conflict->flags & IORESOURCE_BUSY))
> +                       if (!(conflict->flags & IORESOURCE_BUSY)) {
> +                               if (unlikely(

No need for unlikely(), this isn't a hot path.

> +                                   (resource_type(conflict) == IORESOURCE_MEM)
> +                                   && (conflict->flags & IORESOURCE_MEM_WARN)))
> +                                       pr_warn("request region with unknown memory type [mem %#010llx-%#010llx] %s\n",
> +                                               conflict->start, conflict->end,
> +                                               conflict->name);

I think this should also dump the res->name to identify who is requesting it.
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