netdev - Re: [net-next PATCH] amt: Use BIT macros instead of open codes

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Date:   Mon, 02 May 2022 12:11:57 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     Juhee Kang <claudiajkang@...il.com>, ap420073@...il.com,
        davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org
Subject: Re: [net-next PATCH] amt: Use BIT macros instead of open codes

Hello,

On Sat, 2022-04-30 at 13:56 +0000, Juhee Kang wrote:
> Replace open code related to bit operation with BIT macros, which kernel
> provided. This patch provides no functional change.
> 
> Signed-off-by: Juhee Kang <claudiajkang@...il.com>
> ---
>  drivers/net/amt.c | 2 +-
>  include/net/amt.h | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/amt.c b/drivers/net/amt.c
> index 10455c9b9da0..76c1969a03f5 100644
> --- a/drivers/net/amt.c
> +++ b/drivers/net/amt.c
> @@ -959,7 +959,7 @@ static void amt_req_work(struct work_struct *work)
>  	amt_update_gw_status(amt, AMT_STATUS_SENT_REQUEST, true);
>  	spin_lock_bh(&amt->lock);
>  out:
> -	exp = min_t(u32, (1 * (1 << amt->req_cnt)), AMT_MAX_REQ_TIMEOUT);
> +	exp = min_t(u32, (1 * BIT(amt->req_cnt)), AMT_MAX_REQ_TIMEOUT);
>  	mod_delayed_work(amt_wq, &amt->req_wq, msecs_to_jiffies(exp * 1000));
>  	spin_unlock_bh(&amt->lock);
>  }
> diff --git a/include/net/amt.h b/include/net/amt.h
> index 7a4db8b903ee..d2fd76b0a424 100644
> --- a/include/net/amt.h
> +++ b/include/net/amt.h
> @@ -354,7 +354,7 @@ struct amt_dev {
>  #define AMT_MAX_GROUP		32
>  #define AMT_MAX_SOURCE		128
>  #define AMT_HSIZE_SHIFT		8
> -#define AMT_HSIZE		(1 << AMT_HSIZE_SHIFT)
> +#define AMT_HSIZE		BIT(AMT_HSIZE_SHIFT)
>  
>  #define AMT_DISCOVERY_TIMEOUT	5000
>  #define AMT_INIT_REQ_TIMEOUT	1

Even if the 2 replaced statements use shift operations, they do not
look like bit manipulation: the first one is an exponential timeout,
the 2nd one is an (hash) size. I think using the BIT() macro here will
be confusing.

Cheers,

Paolo