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

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Date:   Tue, 29 Jun 2021 21:53:20 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Colin King' <colin.king@...onical.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

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++) {

   David

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