linux-kernel - Re: [PATCH v2] nitro_enclaves: Fix implicit type conversion

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Date:   Wed, 3 Nov 2021 10:13:23 +0100
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>
Cc:     andraprs@...zon.com, lexnv@...zon.com, alcioa@...zon.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] nitro_enclaves: Fix implicit type conversion

On Fri, Oct 29, 2021 at 01:48:46AM +0000, Jiasheng Jiang wrote:
>The variable 'cpu' and 'cpu_sibling' are defined as unsigned int.
>However in the for_each_cpu, their values are assigned to -1.
>That doesn't make sense and in the cpumask_next() they are implicitly
>type conversed to int.
>It is universally accepted that the implicit type conversion is
>terrible.
>Also, having the good programming custom will set an example for
>others.
>Thus, it might be better to change the definition of 'cpu' and
>'cpu_sibling' from unsigned int to int.
>
>Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
>---
> drivers/virt/nitro_enclaves/ne_misc_dev.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)


The for_each_cpu documentation explicitly says that unsigned is 
supported and -1 is commonly used to refer to the value before 0 even 
for unsigned.

However I have nothing against changing them to int.

Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>

Thanks,
Stefano