linux-kernel - Re: [PATCH v8 03/13] kexec_file,x86,powerpc: factor out kexec_file

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Date:   Fri, 23 Feb 2018 17:24:59 +0800
From:   Dave Young <dyoung@...hat.com>
To:     AKASHI Takahiro <takahiro.akashi@...aro.org>
Cc:     catalin.marinas@....com, will.deacon@....com,
        bauerman@...ux.vnet.ibm.com, dhowells@...hat.com,
        vgoyal@...hat.com, herbert@...dor.apana.org.au,
        davem@...emloft.net, akpm@...ux-foundation.org, mpe@...erman.id.au,
        bhe@...hat.com, arnd@...db.de, ard.biesheuvel@...aro.org,
        julien.thierry@....com, kexec@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 03/13] kexec_file,x86,powerpc: factor out
 kexec_file_ops functions

Hi AKASHI,

On 02/22/18 at 08:17pm, AKASHI Takahiro wrote:
> As arch_kexec_kernel_*_{probe,load}(), arch_kimage_file_post_load_cleanup()
> and arch_kexec_kernel_verify_sg can be parameterized with a kexec_file_ops
> array and now duplicated among some architectures, let's factor them out.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> Cc: Dave Young <dyoung@...hat.com>
> Cc: Vivek Goyal <vgoyal@...hat.com>
> Cc: Baoquan He <bhe@...hat.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/kexec.h            |  2 +-
>  arch/powerpc/kernel/kexec_elf_64.c          |  2 +-
>  arch/powerpc/kernel/machine_kexec_file_64.c | 39 ++------------------
>  arch/x86/include/asm/kexec-bzimage64.h      |  2 +-
>  arch/x86/kernel/kexec-bzimage64.c           |  2 +-
>  arch/x86/kernel/machine_kexec_64.c          | 45 +----------------------
>  include/linux/kexec.h                       | 15 ++++----
>  kernel/kexec_file.c                         | 57 +++++++++++++++++++++++++++--
>  8 files changed, 70 insertions(+), 94 deletions(-)
> 

[snip]

> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 990adae52151..a6d14a768b3e 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -26,34 +26,83 @@
>  #include <linux/vmalloc.h>
>  #include "kexec_internal.h"
>  
> +const __weak struct kexec_file_ops * const kexec_file_loaders[] = {NULL};
> +
>  #ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
>  static int kexec_calculate_store_digests(struct kimage *image);
>  #else
>  static int kexec_calculate_store_digests(struct kimage *image) { return 0; };
>  #endif
>  
> +int _kexec_kernel_image_probe(struct kimage *image, void *buf,
> +			     unsigned long buf_len)
> +{
> +	const struct kexec_file_ops * const *fops;
> +	int ret = -ENOEXEC;
> +
> +	for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
> +		ret = (*fops)->probe(buf, buf_len);
> +		if (!ret) {
> +			image->fops = *fops;
> +			return ret;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
>  /* Architectures can provide this probe function */
>  int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
>  					 unsigned long buf_len)
>  {
> -	return -ENOEXEC;
> +	return _kexec_kernel_image_probe(image, buf, buf_len);


I vaguely remember previously I suggest split the _kexec_kernel_image_probe
because arch code can call them, and common code also use it like above.
But in your new series I do not find where else calls this function
except the common code arch_kexec_kernel_image_probe.  If nobody use
them then it is not worth to split them out, it is better to just embed
them in the __weak functions.

Ditto for other similar functions.

[snip]

Thanks
Dave