* [PATCH v2] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
@ 2019-02-19 20:47 Liu Jian
2019-02-22 5:58 ` Vignesh R
0 siblings, 1 reply; 4+ messages in thread
From: Liu Jian @ 2019-02-19 20:47 UTC (permalink / raw)
To: dwmw2, computersforpeace, bbrezillon, marek.vasut, richard,
joakim.tjernlund, ikegami, keescook
Cc: liujian56, linux-mtd, linux-kernel
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@huawei.com>
Signed-off-by: Liu Jian <liujian56@huawei.com>
Reviewed-by: Tokunori Ikegami <ikegami_to@yahoo.co.jp>
---
v1->v2:
change git log, put the Fixes tag on a single line
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);
}
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
2019-02-19 20:47 [PATCH v2] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer Liu Jian
@ 2019-02-22 5:58 ` Vignesh R
2019-02-22 14:50 ` liujian (CE)
0 siblings, 1 reply; 4+ messages in thread
From: Vignesh R @ 2019-02-22 5:58 UTC (permalink / raw)
To: Liu Jian, dwmw2, computersforpeace, bbrezillon, marek.vasut,
richard, joakim.tjernlund, ikegami, keescook
Cc: linux-mtd, linux-kernel
On 20/02/19 2:17 AM, Liu Jian 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.
>
> Fixes: dfeae1073583 ("mtd: cfi_cmdset_0002: Change write buffer to check correct value")
> Signed-off-by: Yi Huaijie <yihuaijie@huawei.com>
> Signed-off-by: Liu Jian <liujian56@huawei.com>
> Reviewed-by: Tokunori Ikegami <ikegami_to@yahoo.co.jp>
> ---
> v1->v2:
> change git log, put the Fixes tag on a single line
>
> 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;
> +
It is quite possible that this thread might be pre-empted just after
chip_good() check but before before time_after(). If the thread, then
resumes execution after timeo has elasped then, this code will wrongly
indicate write failure.
To avoid this case, you should add one more check for check_good() even
when time_after() returns true. Something like:
if (time_after(jiffies, timeo)) {
if (chip_good(map, adr, datum)) {
xip_enable(map, chip, adr);
goto op_done;
}
break;
}
> /* Latency issues. Drop the lock, wait a while and retry */
> UDELAY(map, chip, adr, 1);
> }
>
--
Regards
Vignesh
^ permalink raw reply [flat|nested] 4+ messages in thread
* RE: [PATCH v2] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
2019-02-22 5:58 ` Vignesh R
@ 2019-02-22 14:50 ` liujian (CE)
2019-02-25 15:17 ` Vignesh R
0 siblings, 1 reply; 4+ messages in thread
From: liujian (CE) @ 2019-02-22 14:50 UTC (permalink / raw)
To: Vignesh R, dwmw2, computersforpeace, bbrezillon, marek.vasut,
richard, joakim.tjernlund, ikegami, keescook
Cc: linux-mtd, linux-kernel
> -----Original Message-----
> From: Vignesh R [mailto:vigneshr@ti.com]
> Sent: Friday, February 22, 2019 1:59 PM
> To: liujian (CE) <liujian56@huawei.com>; dwmw2@infradead.org;
> computersforpeace@gmail.com; bbrezillon@kernel.org;
> marek.vasut@gmail.com; richard@nod.at; joakim.tjernlund@infinera.com;
> ikegami@allied-telesis.co.jp; keescook@chromium.org
> Cc: linux-mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v2] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
>
>
>
> On 20/02/19 2:17 AM, Liu Jian 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.
> >
> > Fixes: dfeae1073583 ("mtd: cfi_cmdset_0002: Change write buffer to
> > check correct value")
> > Signed-off-by: Yi Huaijie <yihuaijie@huawei.com>
> > Signed-off-by: Liu Jian <liujian56@huawei.com>
> > Reviewed-by: Tokunori Ikegami <ikegami_to@yahoo.co.jp>
> > ---
> > v1->v2:
> > change git log, put the Fixes tag on a single line
> >
> > 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;
> > +
>
> It is quite possible that this thread might be pre-empted just after
> chip_good() check but before before time_after(). If the thread, then resumes
> execution after timeo has elasped then, this code will wrongly indicate write
> failure.
>
> To avoid this case, you should add one more check for check_good() even when
> time_after() returns true. Something like:
>
> if (time_after(jiffies, timeo)) {
> if (chip_good(map, adr, datum)) {
> xip_enable(map, chip, adr);
> goto op_done;
> }
> break;
> }
>
So, the patch should like this ?
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))
break;
if (chip_good(map, adr, datum)) {
Any other opinions?
If there are no other comments, I will send a patch again
>
> > /* Latency issues. Drop the lock, wait a while and retry */
> > UDELAY(map, chip, adr, 1);
> > }
> >
>
> --
> Regards
> Vignesh
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
2019-02-22 14:50 ` liujian (CE)
@ 2019-02-25 15:17 ` Vignesh R
0 siblings, 0 replies; 4+ messages in thread
From: Vignesh R @ 2019-02-25 15:17 UTC (permalink / raw)
To: liujian (CE),
dwmw2, computersforpeace, bbrezillon, marek.vasut, richard,
joakim.tjernlund, ikegami, keescook
Cc: linux-mtd, linux-kernel
On 22-Feb-19 8:20 PM, liujian (CE) wrote:
>
>> -----Original Message-----
>> From: Vignesh R [mailto:vigneshr@ti.com]
>> Sent: Friday, February 22, 2019 1:59 PM
>> To: liujian (CE) <liujian56@huawei.com>; dwmw2@infradead.org;
>> computersforpeace@gmail.com; bbrezillon@kernel.org;
>> marek.vasut@gmail.com; richard@nod.at; joakim.tjernlund@infinera.com;
>> ikegami@allied-telesis.co.jp; keescook@chromium.org
>> Cc: linux-mtd@lists.infradead.org; linux-kernel@vger.kernel.org
>> Subject: Re: [PATCH v2] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer
>>
>>
>>
>> On 20/02/19 2:17 AM, Liu Jian 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.
>>>
>>> Fixes: dfeae1073583 ("mtd: cfi_cmdset_0002: Change write buffer to
>>> check correct value")
>>> Signed-off-by: Yi Huaijie <yihuaijie@huawei.com>
>>> Signed-off-by: Liu Jian <liujian56@huawei.com>
>>> Reviewed-by: Tokunori Ikegami <ikegami_to@yahoo.co.jp>
>>> ---
>>> v1->v2:
>>> change git log, put the Fixes tag on a single line
>>>
>>> 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;
>>> +
>>
>> It is quite possible that this thread might be pre-empted just after
>> chip_good() check but before before time_after(). If the thread, then resumes
>> execution after timeo has elasped then, this code will wrongly indicate write
>> failure.
>>
>> To avoid this case, you should add one more check for check_good() even when
>> time_after() returns true. Something like:
>>
>> if (time_after(jiffies, timeo)) {
>> if (chip_good(map, adr, datum)) {
>> xip_enable(map, chip, adr);
>> goto op_done;
>> }
>> break;
>> }
>>
> So, the patch should like this ?
>
> 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))
> break;
>
> if (chip_good(map, adr, datum)) {
>
>
>
> Any other opinions?
> If there are no other comments, I will send a patch again
Looks fine to me.. Please submit a new version. Thanks!
Regards
Vignesh
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-02-19 20:47 [PATCH v2] cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer Liu Jian
2019-02-22 5:58 ` Vignesh R
2019-02-22 14:50 ` liujian (CE)
2019-02-25 15:17 ` Vignesh R
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