linux-kernel - RE: [PATCH v3] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer

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Message-ID: <016001d4cf71$865e7b60$931b7220$@gmail.com>
Date:   Thu, 28 Feb 2019 23:25:54 +0900
From:   "Tokunori Ikegami" <ikegami.t@...il.com>
To:     "'Liu Jian'" <liujian56@...wei.com>, <dwmw2@...radead.org>,
        <computersforpeace@...il.com>, <bbrezillon@...nel.org>,
        <marek.vasut@...il.com>, <richard@....at>,
        <joakim.tjernlund@...inera.com>, <ikegami@...ied-telesis.co.jp>,
        <keescook@...omium.org>, <vigneshr@...com>
Cc:     <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer

> -----Original Message-----
> From: linux-mtd [mailto:linux-mtd-bounces@...ts.infradead.org] On Behalf
> Of Liu Jian
> Sent: Tuesday, February 26, 2019 11:01 PM
> To: dwmw2@...radead.org; computersforpeace@...il.com;
> bbrezillon@...nel.org; marek.vasut@...il.com; richard@....at;
> joakim.tjernlund@...inera.com; ikegami@...ied-telesis.co.jp;
> keescook@...omium.org; vigneshr@...com
> Cc: linux-mtd@...ts.infradead.org; liujian56@...wei.com;
> linux-kernel@...r.kernel.org
> Subject: [PATCH v3] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
> 
> 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.
> 
> Fixes: dfeae1073583("mtd: cfi_cmdset_0002: Change write buffer to check
> correct value")
> Signed-off-by: Yi Huaijie <yihuaijie@...wei.com>
> Signed-off-by: Liu Jian <liujian56@...wei.com>
> Reviewed-by: Tokunori Ikegami <ikegami_to@...oo.co.jp>
> ---
> v2->v3:
> Follow Vignesh's advice:
> add one more check for check_good() even when time_after() returns true.
> 
>  drivers/mtd/chips/cfi_cmdset_0002.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c
> b/drivers/mtd/chips/cfi_cmdset_0002.c
> index 72428b6..3da2376 100644
> --- a/drivers/mtd/chips/cfi_cmdset_0002.c
> +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
> @@ -1876,7 +1876,7 @@ static int __xipram do_write_buffer(struct map_info
> *map, struct flchip *chip,
>  			continue;
>  		}
> 
> -		if (time_after(jiffies, timeo) && !chip_ready(map, adr))
> +		if (time_after(jiffies, timeo) && !chip_good(map, adr,
> datum))

  Just another idea to understand easily.

    unsigned long now = jiffies;

    if (chip_good(map, adr, datum)) {
        xip_enable(map, chip, adr);
        goto op_done;
    }

    if (time_after(now, timeo) {
        break;
    }

Regards,
Ikegami

>  			break;
> 
>  		if (chip_good(map, adr, datum)) {
> --
> 2.7.4
> 
> 
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/

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