linux-kernel - Re: [PATCH v20 1/5] arm64: Use insert

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Message-ID: <171196ee-8c61-2ebd-b74d-87c0a15ae4ea@oracle.com>
Date:   Wed, 26 Jan 2022 09:16:38 -0600
From:   john.p.donnelly@...cle.com
To:     Zhen Lei <thunder.leizhen@...wei.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H . Peter Anvin" <hpa@...or.com>,
        linux-kernel@...r.kernel.org, Dave Young <dyoung@...hat.com>,
        Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        kexec@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org, Jonathan Corbet <corbet@....net>,
        linux-doc@...r.kernel.org
Cc:     Randy Dunlap <rdunlap@...radead.org>,
        Feng Zhou <zhoufeng.zf@...edance.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Chen Zhou <dingguo.cz@...group.com>,
        Dave Kleikamp <dave.kleikamp@...cle.com>,
        John Donnelly <john.p.donnelly@...cle.com>
Subject: Re: [PATCH v20 1/5] arm64: Use insert_resource() to simplify code

On 1/24/22 2:47 AM, Zhen Lei wrote:
> insert_resource() traverses the subtree layer by layer from the root node
> until a proper location is found. Compared with request_resource(), the
> parent node does not need to be determined in advance.
> 
> In addition, move the insertion of node 'crashk_res' into function
> reserve_crashkernel() to make the associated code close together.
> 
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>


Acked-by: John Donnelly  <john.p.donnelly@...cle.com>

> ---
>   arch/arm64/kernel/setup.c | 17 +++--------------
>   arch/arm64/mm/init.c      |  1 +
>   2 files changed, 4 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index f70573928f1bff0..a81efcc359e4e78 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -225,6 +225,8 @@ static void __init request_standard_resources(void)
>   	kernel_code.end     = __pa_symbol(__init_begin - 1);
>   	kernel_data.start   = __pa_symbol(_sdata);
>   	kernel_data.end     = __pa_symbol(_end - 1);
> +	insert_resource(&iomem_resource, &kernel_code);
> +	insert_resource(&iomem_resource, &kernel_data);
>   
>   	num_standard_resources = memblock.memory.cnt;
>   	res_size = num_standard_resources * sizeof(*standard_resources);
> @@ -246,20 +248,7 @@ static void __init request_standard_resources(void)
>   			res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
>   		}
>   
> -		request_resource(&iomem_resource, res);
> -
> -		if (kernel_code.start >= res->start &&
> -		    kernel_code.end <= res->end)
> -			request_resource(res, &kernel_code);
> -		if (kernel_data.start >= res->start &&
> -		    kernel_data.end <= res->end)
> -			request_resource(res, &kernel_data);
> -#ifdef CONFIG_KEXEC_CORE
> -		/* Userspace will find "Crash kernel" region in /proc/iomem. */
> -		if (crashk_res.end && crashk_res.start >= res->start &&
> -		    crashk_res.end <= res->end)
> -			request_resource(res, &crashk_res);
> -#endif
> +		insert_resource(&iomem_resource, res);
>   	}
>   }
>   
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index db63cc885771a52..90f276d46b93bc6 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -109,6 +109,7 @@ static void __init reserve_crashkernel(void)
>   	kmemleak_ignore_phys(crash_base);
>   	crashk_res.start = crash_base;
>   	crashk_res.end = crash_base + crash_size - 1;
> +	insert_resource(&iomem_resource, &crashk_res);
>   }
>   #else
>   static void __init reserve_crashkernel(void)