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

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Date:   Sun, 3 Feb 2019 09:35:09 +0100
From:   Boris Brezillon <bbrezillon@...nel.org>
To:     Liu Jian <liujian56@...wei.com>, <ikegami@...ied-telesis.co.jp>
Cc:     <dwmw2@...radead.org>, <computersforpeace@...il.com>,
        <marek.vasut@...il.com>, <richard@....at>,
        <joakim.tjernlund@...inera.com>, <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

On Sun, 3 Feb 2019 09:26:45 +0100
Boris Brezillon <bbrezillon@...nel.org> wrote:

> +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);
> >  	}  
> 

BTW, the patch itself looks good to me. Ikegami, can you confirm it
does the right thing?

Thanks,

Boris