Received-SPF: pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org F1143608D4
From:   Kalle Valo <kvalo@codeaurora.org>
To:     <yhchuang@realtek.com>
Cc:     <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH 5/6] rtw88: mac: remove dangerous while (1)
References: <1556879502-16211-1-git-send-email-yhchuang@realtek.com>
        <1556879502-16211-6-git-send-email-yhchuang@realtek.com>
Date:   Fri, 03 May 2019 14:07:03 +0300
In-Reply-To: <1556879502-16211-6-git-send-email-yhchuang@realtek.com>
        (yhchuang@realtek.com's message of "Fri, 3 May 2019 18:31:41 +0800")
Message-ID: <87r29fkd9k.fsf@kamboji.qca.qualcomm.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

<yhchuang@realtek.com> writes:

> From: Yan-Hsuan Chuang <yhchuang@realtek.com>
>
> Not to use while (1) to parse power sequence commands in an array.
> Put the statement (when cmd is not NULL) instead to make the loop stop
> when the next fetched command is NULL.
>
> Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
> ---
>  drivers/net/wireless/realtek/rtw88/mac.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/wireless/realtek/rtw88/mac.c b/drivers/net/wireless/realtek/rtw88/mac.c
> index 25a923b..7487b2e 100644
> --- a/drivers/net/wireless/realtek/rtw88/mac.c
> +++ b/drivers/net/wireless/realtek/rtw88/mac.c
> @@ -203,17 +203,14 @@ static int rtw_pwr_seq_parser(struct rtw_dev *rtwdev,
>  		return -EINVAL;
>  	}
>  
> -	do {
> -		cmd = cmd_seq[idx];
> -		if (!cmd)
> -			break;
> -
> +	while ((cmd = cmd_seq[idx])) {
>  		ret = rtw_sub_pwr_seq_parser(rtwdev, intf_mask, cut_mask, cmd);
>  		if (ret)
>  			return -EBUSY;
>  
> +		/* fetch next command */
>  		idx++;
> -	} while (1);
> +	};

I dount see how this is any better, with a suitable bug you can still
have a neverending loop, right? I was thinking more something like this:

count = 100;
do {
    ....
} while (count--);

That way the won't be more than 100 loops no matter how many bugs there
are :) Of course I have no idea what would be a good value for count.

-- 
Kalle Valo