linux-kernel - Re: [PATCH v2 1/7] kernel/resource: make release_mem_region

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Message-ID: <20200915090612.GA6936@L-31X9LVDL-1304.local>
Date:   Tue, 15 Sep 2020 17:06:12 +0800
From:   Wei Yang <richard.weiyang@...ux.alibaba.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     Wei Yang <richard.weiyang@...ux.alibaba.com>,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        linux-hyperv@...r.kernel.org, xen-devel@...ts.xenproject.org,
        linux-acpi@...r.kernel.org, linux-nvdimm@...ts.01.org,
        linux-s390@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Kees Cook <keescook@...omium.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Baoquan He <bhe@...hat.com>
Subject: Re: [PATCH v2 1/7] kernel/resource: make
 release_mem_region_adjustable() never fail

On Tue, Sep 15, 2020 at 09:35:30AM +0200, David Hildenbrand wrote:
>
>>> static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>> {
>>> 	int rc = 0;
>>> @@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
>>> 		memblock_remove(start, size);
>>> 	}
>>>
>>> -	__release_memory_resource(start, size);
>>> +	release_mem_region_adjustable(&iomem_resource, start, size);
>>>
>> 
>> Seems the only user of release_mem_region_adjustable() is here, can we move
>> iomem_resource into the function body? Actually, we don't iterate the resource
>> tree from any level. We always start from the root.
>
>You mean, making iomem_resource implicit? I can spot that something
>similar was done for
>
>#define devm_release_mem_region(dev, start, n) \
>	__devm_release_region(dev, &iomem_resource, (start), (n))
>

What I prefer is remove iomem_resource from the parameter list. Just use is in
the function body.

For the example you listed, __release_region() would have varies of *parent*,
which looks reasonable to keep it here.

>I'll send an addon patch for that, ok? - thanks.
>
>-- 
>Thanks,
>
>David / dhildenb

-- 
Wei Yang
Help you, Help me