linux-kernel - Re: [PATCH] cfi: fix deadloop in cfi_cmdset_0002.c do_write

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Date:   Sun, 3 Feb 2019 09:26:45 +0100
From:   Boris Brezillon <bbrezillon@...nel.org>
To:     Liu Jian <liujian56@...wei.com>
Cc:     <dwmw2@...radead.org>, <computersforpeace@...il.com>,
        <marek.vasut@...il.com>, <richard@....at>,
        <joakim.tjernlund@...inera.com>, <ikegami@...ied-telesis.co.jp>,
        <keescook@...omium.org>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Przemyslaw Sobon <psobon@...zon.com>
Subject: Re: [PATCH] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer

+Przemyslaw

On Fri, 1 Feb 2019 07:30:39 +0800
Liu Jian <liujian56@...wei.com> wrote:

> In function do_write_buffer(), in the for loop, there is a case
> chip_ready() returns 1 while chip_good() returns 0, so it never
> break the loop.
> To fix this, chip_good() is enough and it should timeout if it stay
> bad for a while.

Looks like Przemyslaw reported and fixed the same problem.

> 
> Fixes: dfeae1073583(mtd: cfi_cmdset_0002: Change write buffer to check
> correct value)

Can you put the Fixes tag on a single, and the format is

Fixes: <hash> ("message")

> Signed-off-by: Yi Huaijie <yihuaijie@...wei.com>
> Signed-off-by: Liu Jian <liujian56@...wei.com>

[1]http://patchwork.ozlabs.org/patch/1025566/

> ---
>  drivers/mtd/chips/cfi_cmdset_0002.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
> index 72428b6..818e94b 100644
> --- a/drivers/mtd/chips/cfi_cmdset_0002.c
> +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
> @@ -1876,14 +1876,14 @@ static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
>  			continue;
>  		}
>  
> -		if (time_after(jiffies, timeo) && !chip_ready(map, adr))
> -			break;
> -
>  		if (chip_good(map, adr, datum)) {
>  			xip_enable(map, chip, adr);
>  			goto op_done;
>  		}
>  
> +		if (time_after(jiffies, timeo))
> +			break;
> +
>  		/* Latency issues. Drop the lock, wait a while and retry */
>  		UDELAY(map, chip, adr, 1);
>  	}