Re: [PATCH v8 03/13] kexec_file,x86,powerpc: factor out kexec_file_ops functions

From: Dave Young <dyoung@redhat.com>
To: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: catalin.marinas@arm.com, will.deacon@arm.com,
	bauerman@linux.vnet.ibm.com, dhowells@redhat.com,
	vgoyal@redhat.com, herbert@gondor.apana.org.au,
	davem@davemloft.net, akpm@linux-foundation.org,
	mpe@ellerman.id.au, bhe@redhat.com, arnd@arndb.de,
	ard.biesheuvel@linaro.org, julien.thierry@arm.com,
	kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 03/13] kexec_file,x86,powerpc: factor out kexec_file_ops functions
Date: Fri, 23 Feb 2018 17:24:59 +0800	[thread overview]
Message-ID: <20180223092459.GC4433@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <20180222111732.23051-4-takahiro.akashi@linaro.org>

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@linaro.org>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Vivek Goyal <vgoyal@redhat.com>
> Cc: Baoquan He <bhe@redhat.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Thiago Jung Bauermann <bauerman@linux.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