linux-kernel - Re: [PATCH] kexec: Delete an unnecessary comparison

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Date:   Fri, 14 Aug 2020 18:11:34 +0800
From:   Youling Tang <tangyouling@...ngson.cn>
To:     Joe Perches <joe@...ches.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        Vivek Goyal <vgoyal@...hat.com>
Cc:     kexec@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kexec: Delete an unnecessary comparison



On 08/14/2020 02:07 PM, Joe Perches wrote:
> On Thu, 2020-08-13 at 20:45 +0800, Youling Tang wrote:
>> Regardless of whether the ret value is zero or non-zero, the trajectory
>> of the program execution is the same, so there is no need to compare.
>>
>> Signed-off-by: Youling Tang <tangyouling@...ngson.cn>
>> ---
>>   kernel/kexec_file.c | 2 --
>>   1 file changed, 2 deletions(-)
>>
>> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
>> index 78c0837..3ad0ae2 100644
>> --- a/kernel/kexec_file.c
>> +++ b/kernel/kexec_file.c
>> @@ -800,8 +800,6 @@ static int kexec_calculate_store_digests(struct kimage *image)
>>   
>>   		ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
>>   						     digest, SHA256_DIGEST_SIZE, 0);
>> -		if (ret)
>> -			goto out_free_digest;
>>   	}
>>   
>>   out_free_digest:
> If you really want to change the function, then
> you could change a couple of breaks to gotos,
> remove multiple unnecessary tests, and unindent
> a block of code too.
>
> ---
>   kernel/kexec_file.c | 30 ++++++++++++------------------
>   1 file changed, 12 insertions(+), 18 deletions(-)
>
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index ca40bef75a61..34a025e85887 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -763,7 +763,7 @@ static int kexec_calculate_store_digests(struct kimage *image)
>   		ret = crypto_shash_update(desc, ksegment->kbuf,
>   					  ksegment->bufsz);
>   		if (ret)
> -			break;
> +			goto out_free_digest;
>   
>   		/*
>   		 * Assume rest of the buffer is filled with zero and
> @@ -777,32 +777,26 @@ static int kexec_calculate_store_digests(struct kimage *image)
>   				bytes = zero_buf_sz;
>   			ret = crypto_shash_update(desc, zero_buf, bytes);
>   			if (ret)
> -				break;
> +				goto out_free_digest;
>   			nullsz -= bytes;
>   		}
>   
> -		if (ret)
> -			break;
> -
>   		sha_regions[j].start = ksegment->mem;
>   		sha_regions[j].len = ksegment->memsz;
>   		j++;
>   	}
>   
> -	if (!ret) {
> -		ret = crypto_shash_final(desc, digest);
> -		if (ret)
> -			goto out_free_digest;
> -		ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
> -						     sha_regions, sha_region_sz, 0);
> -		if (ret)
> -			goto out_free_digest;
> +	ret = crypto_shash_final(desc, digest);
> +	if (ret)
> +		goto out_free_digest;
>   
> -		ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
> -						     digest, SHA256_DIGEST_SIZE, 0);
> -		if (ret)
> -			goto out_free_digest;
> -	}
> +	ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
> +					     sha_regions, sha_region_sz, 0);
> +	if (ret)
> +		goto out_free_digest;
> +
> +	ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
> +					     digest, SHA256_DIGEST_SIZE, 0);
>   
>   out_free_digest:
>   	kfree(digest);
>
OK, looks good to me, I will send v2.

Thanks,
Youling