linux-kernel - Re: [PATCH] staging: r8188eu: Fix while-loop that iterates only once

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Message-ID: <b989a309-b706-2197-f0f7-51e838f4fcdf@canonical.com>
Date:   Wed, 30 Jun 2021 07:44:47 +0100
From:   Colin Ian King <colin.king@...onical.com>
To:     David Laight <David.Laight@...LAB.COM>,
        Larry Finger <Larry.Finger@...inger.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-staging@...ts.linux.dev" <linux-staging@...ts.linux.dev>
Cc:     "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] staging: r8188eu: Fix while-loop that iterates only once

On 29/06/2021 22:53, David Laight wrote:
> From: Colin King
>> Sent: 29 June 2021 17:36
>>
>> The while-loop only iterates once becase the post increment test of count
>> being non-zero is false on the first iteration because count is zero. Fix
>> this by incrementing count using pre-increment. Static analysis found the
>> issue on the count > POLLING_LLT_THRESHOLD check always being false since
>> the loop currently just iterates once.
> 
> But that is a very strange 'loop bottom'.
> 
> ...
>> diff --git a/drivers/staging/rtl8188eu/hal/rtl8188e_hal_init.c
>> b/drivers/staging/rtl8188eu/hal/rtl8188e_hal_init.c
>> index d1086699f952..db57f04e7e56 100644
>> --- a/drivers/staging/rtl8188eu/hal/rtl8188e_hal_init.c
>> +++ b/drivers/staging/rtl8188eu/hal/rtl8188e_hal_init.c
>> @@ -185,7 +185,7 @@ static s32 _LLTWrite(struct adapter *padapter, u32 address, u32 data)
>>  			break;
>>  		}
>>  		udelay(5);
>> -	} while (count++);
>> +	} while (++count);
> 
> Unless 'count' is negative that might as well be 'while (1)'
> with count incremented elsewhere.
> Perhaps the loop top should be:
> 	for (count = 0;; count++) {

I'll rework it, thanks for the input.

> 
>    David
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
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