Re: [PATCH 4/9] mtd: nand: qcom: fix null pointer access for erased buffer detection

2018-04-22 Thread Abhishek Sahu 

On 2018-04-22 21:55, Miquel Raynal wrote:

Hi Abhishek,

On Thu, 12 Apr 2018 12:24:16 +0530, Abhishek Sahu
 wrote:


On 2018-04-10 14:42, Miquel Raynal wrote:
> Hi Abhishek,
> > On Wed,  4 Apr 2018 18:12:20 +0530, Abhishek Sahu
>  wrote:
> >> parse_read_errors can be called with only oob buf also in which
>> case data_buf will be NULL.  If data_buf is NULL, then don’t
>> treat this page as completely erased in case of ECC uncorrectable
>> error.
>> >> Signed-off-by: Abhishek Sahu 
>> ---
>>  drivers/mtd/nand/qcom_nandc.c | 7 +--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>> >> diff --git a/drivers/mtd/nand/qcom_nandc.c >> 
b/drivers/mtd/nand/qcom_nandc.c
>> index 57c16a6..0ebcc55 100644
>> --- a/drivers/mtd/nand/qcom_nandc.c
>> +++ b/drivers/mtd/nand/qcom_nandc.c
>> @@ -1607,9 +1607,11 @@ static int parse_read_errors(struct >> qcom_nand_host 
*host, u8 *data_buf,
>>if (host->bch_enabled) {
>>erased = (erased_cw & ERASED_CW) == ERASED_CW 
?
>> true : false;
> > Why the parse_read_errors() function could not be called without
> data_buf when using BCH? Are you sure the situation can only happen
> without it?
>
   host->bch_enabled case is different where controller itself tells
   regarding erased page in status register.

> Would the following apply here too, with a:
>
  erased_chunk_check_and_fixup will be used only for 4 bit RS ECC
  code in which there is no support from HW for erased page detection
  and we need to check few data bytes value.


So please explain this with a comment.

Thanks,
Miquèl


 Sure Miquel.
 I will do the same and update the patch with more comments.

 Thanks,
 Abhishek

Re: [PATCH 4/9] mtd: nand: qcom: fix null pointer access for erased buffer detection

2018-04-22 Thread Miquel Raynal 
Hi Abhishek,

On Thu, 12 Apr 2018 12:24:16 +0530, Abhishek Sahu
 wrote:

> On 2018-04-10 14:42, Miquel Raynal wrote:
> > Hi Abhishek,  
> > > On Wed,  4 Apr 2018 18:12:20 +0530, Abhishek Sahu  
> >  wrote:  
> > >> parse_read_errors can be called with only oob buf also in which  
> >> case data_buf will be NULL.  If data_buf is NULL, then don’t
> >> treat this page as completely erased in case of ECC uncorrectable
> >> error.  
> >> >> Signed-off-by: Abhishek Sahu   
> >> ---
> >>  drivers/mtd/nand/qcom_nandc.c | 7 +--
> >>  1 file changed, 5 insertions(+), 2 deletions(-)  
> >> >> diff --git a/drivers/mtd/nand/qcom_nandc.c >> 
> >> >> b/drivers/mtd/nand/qcom_nandc.c  
> >> index 57c16a6..0ebcc55 100644
> >> --- a/drivers/mtd/nand/qcom_nandc.c
> >> +++ b/drivers/mtd/nand/qcom_nandc.c
> >> @@ -1607,9 +1607,11 @@ static int parse_read_errors(struct >> 
> >> qcom_nand_host *host, u8 *data_buf,
> >>if (host->bch_enabled) {
> >>erased = (erased_cw & ERASED_CW) == ERASED_CW ?
> >> true : false;
> > > Why the parse_read_errors() function could not be called without  
> > data_buf when using BCH? Are you sure the situation can only happen
> > without it?
> >   
>host->bch_enabled case is different where controller itself tells
>regarding erased page in status register.
> 
> > Would the following apply here too, with a:
> >   
>   erased_chunk_check_and_fixup will be used only for 4 bit RS ECC
>   code in which there is no support from HW for erased page detection
>   and we need to check few data bytes value.

So please explain this with a comment.

Thanks,
Miquèl

Re: [PATCH 4/9] mtd: nand: qcom: fix null pointer access for erased buffer detection

2018-04-11 Thread Abhishek Sahu 

On 2018-04-10 14:42, Miquel Raynal wrote:

Hi Abhishek,

On Wed,  4 Apr 2018 18:12:20 +0530, Abhishek Sahu
 wrote:


parse_read_errors can be called with only oob buf also in which
case data_buf will be NULL.  If data_buf is NULL, then don’t
treat this page as completely erased in case of ECC uncorrectable
error.

Signed-off-by: Abhishek Sahu 
---
 drivers/mtd/nand/qcom_nandc.c | 7 +--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/qcom_nandc.c 
b/drivers/mtd/nand/qcom_nandc.c

index 57c16a6..0ebcc55 100644
--- a/drivers/mtd/nand/qcom_nandc.c
+++ b/drivers/mtd/nand/qcom_nandc.c
@@ -1607,9 +1607,11 @@ static int parse_read_errors(struct 
qcom_nand_host *host, u8 *data_buf,

if (host->bch_enabled) {
erased = (erased_cw & ERASED_CW) == ERASED_CW ?
 true : false;


Why the parse_read_errors() function could not be called without
data_buf when using BCH? Are you sure the situation can only happen
without it?



  host->bch_enabled case is different where controller itself tells
  regarding erased page in status register.


Would the following apply here too, with a:



 erased_chunk_check_and_fixup will be used only for 4 bit RS ECC
 code in which there is no support from HW for erased page detection
 and we need to check few data bytes value.

 Thanks,
 Abhishek


if (!data_buf) {
erased = false;
} else {
if (host->bch_enabled)
...
else
...
}


-   } else {
+   } else if (data_buf) {
erased = erased_chunk_check_and_fixup(data_buf,
  data_len);
+   } else {
+   erased = false;
}

if (erased) {
@@ -1652,7 +1654,8 @@ static int parse_read_errors(struct 
qcom_nand_host *host, u8 *data_buf,

max_bitflips = max(max_bitflips, stat);
}

-   data_buf += data_len;
+   if (data_buf)
+   data_buf += data_len;
if (oob_buf)
oob_buf += oob_len + ecc->bytes;
}


Thanks,
Miquèl

Re: [PATCH 4/9] mtd: nand: qcom: fix null pointer access for erased buffer detection

2018-04-10 Thread Miquel Raynal 
Hi Abhishek,

On Wed,  4 Apr 2018 18:12:20 +0530, Abhishek Sahu
 wrote:

> parse_read_errors can be called with only oob buf also in which
> case data_buf will be NULL.  If data_buf is NULL, then don’t
> treat this page as completely erased in case of ECC uncorrectable
> error.
> 
> Signed-off-by: Abhishek Sahu 
> ---
>  drivers/mtd/nand/qcom_nandc.c | 7 +--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c
> index 57c16a6..0ebcc55 100644
> --- a/drivers/mtd/nand/qcom_nandc.c
> +++ b/drivers/mtd/nand/qcom_nandc.c
> @@ -1607,9 +1607,11 @@ static int parse_read_errors(struct qcom_nand_host 
> *host, u8 *data_buf,
>   if (host->bch_enabled) {
>   erased = (erased_cw & ERASED_CW) == ERASED_CW ?
>true : false;

Why the parse_read_errors() function could not be called without
data_buf when using BCH? Are you sure the situation can only happen
without it?

Would the following apply here too, with a:

if (!data_buf) {
erased = false;
} else {
if (host->bch_enabled)
...
else
...
}

> - } else {
> + } else if (data_buf) {
>   erased = erased_chunk_check_and_fixup(data_buf,
> data_len);
> + } else {
> + erased = false;
>   }
>  
>   if (erased) {
> @@ -1652,7 +1654,8 @@ static int parse_read_errors(struct qcom_nand_host 
> *host, u8 *data_buf,
>   max_bitflips = max(max_bitflips, stat);
>   }
>  
> - data_buf += data_len;
> + if (data_buf)
> + data_buf += data_len;
>   if (oob_buf)
>   oob_buf += oob_len + ecc->bytes;
>   }

Thanks,
Miquèl

-- 
Miquel Raynal, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

[PATCH 4/9] mtd: nand: qcom: fix null pointer access for erased buffer detection

2018-04-04 Thread Abhishek Sahu 
parse_read_errors can be called with only oob buf also in which
case data_buf will be NULL.  If data_buf is NULL, then don’t
treat this page as completely erased in case of ECC uncorrectable
error.

Signed-off-by: Abhishek Sahu 
---
 drivers/mtd/nand/qcom_nandc.c | 7 +--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c
index 57c16a6..0ebcc55 100644
--- a/drivers/mtd/nand/qcom_nandc.c
+++ b/drivers/mtd/nand/qcom_nandc.c
@@ -1607,9 +1607,11 @@ static int parse_read_errors(struct qcom_nand_host 
*host, u8 *data_buf,
if (host->bch_enabled) {
erased = (erased_cw & ERASED_CW) == ERASED_CW ?
 true : false;
-   } else {
+   } else if (data_buf) {
erased = erased_chunk_check_and_fixup(data_buf,
  data_len);
+   } else {
+   erased = false;
}
 
if (erased) {
@@ -1652,7 +1654,8 @@ static int parse_read_errors(struct qcom_nand_host *host, 
u8 *data_buf,
max_bitflips = max(max_bitflips, stat);
}
 
-   data_buf += data_len;
+   if (data_buf)
+   data_buf += data_len;
if (oob_buf)
oob_buf += oob_len + ecc->bytes;
}
-- 
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