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

[liujian (CE)]

> -----Original Message-----
> From: Tokunori Ikegami [mailto:ikegami.t@xxxxxxxxx]
> Sent: Thursday, February 28, 2019 10:26 PM
> To: liujian (CE) <liujian56@xxxxxxxxxx>; dwmw2@xxxxxxxxxxxxx;
> computersforpeace@xxxxxxxxx; bbrezillon@xxxxxxxxxx;
> marek.vasut@xxxxxxxxx; richard@xxxxxx; joakim.tjernlund@xxxxxxxxxxxx;
> ikegami@xxxxxxxxxxxxxxxxxxxx; keescook@xxxxxxxxxxxx; vigneshr@xxxxxx
> Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: RE: [PATCH v3] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
> 
> 
> 
> > -----Original Message-----
> > From: linux-mtd [mailto:linux-mtd-bounces@xxxxxxxxxxxxxxxxxxx] On
> > Behalf Of Liu Jian
> > Sent: Tuesday, February 26, 2019 11:01 PM
> > To: dwmw2@xxxxxxxxxxxxx; computersforpeace@xxxxxxxxx;
> > bbrezillon@xxxxxxxxxx; marek.vasut@xxxxxxxxx; richard@xxxxxx;
> > joakim.tjernlund@xxxxxxxxxxxx; ikegami@xxxxxxxxxxxxxxxxxxxx;
> > keescook@xxxxxxxxxxxx; vigneshr@xxxxxx
> > Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx; liujian56@xxxxxxxxxx;
> > linux-kernel@xxxxxxxxxxxxxxx
> > 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@xxxxxxxxxx>
> > Signed-off-by: Liu Jian <liujian56@xxxxxxxxxx>
> > Reviewed-by: Tokunori Ikegami <ikegami_to@xxxxxxxxxxx>
> > ---
> > 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
> >
> >
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