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

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Message-ID: <4F88C5DDA1E80143B232E89585ACE27D0264F137@DGGEMM528-MBX.china.huawei.com>
Date:   Thu, 28 Feb 2019 15:12:15 +0000
From:   "liujian (CE)" <liujian56@...wei.com>
To:     Tokunori Ikegami <ikegami.t@...il.com>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "computersforpeace@...il.com" <computersforpeace@...il.com>,
        "bbrezillon@...nel.org" <bbrezillon@...nel.org>,
        "marek.vasut@...il.com" <marek.vasut@...il.com>,
        "richard@....at" <richard@....at>,
        "joakim.tjernlund@...inera.com" <joakim.tjernlund@...inera.com>,
        "ikegami@...ied-telesis.co.jp" <ikegami@...ied-telesis.co.jp>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "vigneshr@...com" <vigneshr@...com>
CC:     "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3] cfi: fix deadloop in cfi_cmdset_0002.c
 do_write_buffer

> -----Original Message-----
> From: Tokunori Ikegami [mailto:ikegami.t@...il.com]
> Sent: Thursday, February 28, 2019 10:26 PM
> To: liujian (CE) <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;
>     }
> 

Thank you~. It is more easier to understand！
If there are no other comments, I will send new patch again ):  

Best Regards,
Liujian

> 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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