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From: Borislav Petkov <bp@suse.de>
To: Baoquan He <bhe@redhat.com>
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
	robh+dt@kernel.org, dan.j.williams@intel.com,
	nicolas.pitre@linaro.org, josh@joshtriplett.org,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Brijesh Singh" <brijesh.singh@amd.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Tom Lendacky" <thomas.lendacky@amd.com>,
	"Wei Yang" <richard.weiyang@gmail.com>
Subject: Re: [PATCH v3 2/3] resource: add walk_system_ram_res_rev()
Date: Thu, 19 Apr 2018 12:07:45 +0200	[thread overview]
Message-ID: <20180419100745.GC3896@pd.tnic> (raw)
In-Reply-To: <20180419001848.3041-3-bhe@redhat.com>

On Thu, Apr 19, 2018 at 08:18:47AM +0800, Baoquan He wrote:
> This function, being a variant of walk_system_ram_res() introduced in
> commit 8c86e70acead ("resource: provide new functions to walk through
> resources"), walks through a list of all the resources of System RAM
> in reversed order, i.e., from higher to lower.
> 
> It will be used in kexec_file code.

Of course, what is missing is the big *WHY* you need this to happen this
way...

>  /*
> + * This function, being a variant of walk_system_ram_res(), calls the @func
> + * callback against all memory ranges of type System RAM which are marked as
> + * IORESOURCE_SYSTEM_RAM and IORESOUCE_BUSY in reversed order, i.e., from
> + * higher to lower.
> + */
> +int walk_system_ram_res_rev(u64 start, u64 end, void *arg,
> +				int (*func)(struct resource *, void *))
> +{
> +	unsigned long flags;
> +	struct resource *res;
> +	int ret = -1;
> +
> +	flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> +
> +	read_lock(&resource_lock);
> +	list_for_each_entry_reverse(res, &iomem_resource.child, sibling) {

... and the other thing that I'm not clear on is why are you
slapping this function just like that instead of extending
__walk_iomem_res_desc() to do reverse direction too?

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
-- 

  reply	other threads:[~2018-04-19 10:07 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-19  0:18 [PATCH v3 0/3] resource: Use list_head to link sibling resource Baoquan He
2018-04-19  0:18 ` [PATCH v3 1/3] " Baoquan He
2018-04-26  1:18   ` Wei Yang
2018-05-07  1:14     ` Baoquan He
2018-05-08 11:48       ` Wei Yang
2018-05-08 12:11         ` Baoquan He
2018-05-08 23:41           ` Wei Yang
2018-04-26  3:01   ` kbuild test robot
2018-05-06  6:31     ` Baoquan He
2018-04-26  3:23   ` kbuild test robot
2018-05-06  6:30     ` Baoquan He
2018-04-19  0:18 ` [PATCH v3 2/3] resource: add walk_system_ram_res_rev() Baoquan He
2018-04-19 10:07   ` Borislav Petkov [this message]
2018-04-26  8:56     ` Baoquan He
2018-04-26 11:09       ` Borislav Petkov
2018-04-26 13:22         ` Baoquan He
2018-05-04 10:16           ` Borislav Petkov
2018-05-06  6:19             ` Baoquan He
2018-04-19  0:18 ` [PATCH v3 3/3] kexec_file: Load kernel at top of system RAM if required Baoquan He

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