[2/2] jffs2: fix buffer dump debug output

This patch fixes __jffs2_dbg_dump_buffer(): this function prints a message
claiming to dump len bytes. However, depending on the start offset, the former
code drops up to 31 (JFFS2_BUFDUMP_BYTES_PER_LINE - 1) bytes.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
---
 fs/jffs2/debug.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

On Tue, 2014-10-21 at 10:05 +0200, Cyrille Pitchen wrote:
> This patch fixes __jffs2_dbg_dump_buffer(): this function prints a message
> claiming to dump len bytes. However, depending on the start offset, the former
> code drops up to 31 (JFFS2_BUFDUMP_BYTES_PER_LINE - 1) bytes.
> 
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
> ---
>  fs/jffs2/debug.c | 21 ++++++++-------------
>  1 file changed, 8 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/jffs2/debug.c b/fs/jffs2/debug.c
> index 07bd5bc..1b515b2 100644
> --- a/fs/jffs2/debug.c
> +++ b/fs/jffs2/debug.c
> @@ -736,30 +736,25 @@ void
>  __jffs2_dbg_dump_buffer(unsigned char *buf, int len, uint32_t offs)
>  {
>  	int skip;
> -	int i;
> +	int i, pos;
>  
>  	printk(JFFS2_DBG_MSG_PREFIX " dump from offset %#08x to offset %#08x (%x bytes).\n",
>  		offs, offs + len, len);
> -	i = skip = offs % JFFS2_BUFDUMP_BYTES_PER_LINE;
> +	i = skip = offs & (JFFS2_BUFDUMP_BYTES_PER_LINE - 1);
>  	offs = offs & ~(JFFS2_BUFDUMP_BYTES_PER_LINE - 1);
>  
> -	if (skip != 0)
> -		printk(JFFS2_DBG "%#08x: ", offs);
> -
> +	printk(JFFS2_DBG "%#08x: ", offs);
>  	while (skip--)
>  		printk("   ");
>  
> -	while (i < len) {
> -		if ((i % JFFS2_BUFDUMP_BYTES_PER_LINE) == 0 && i != len -1) {
> -			if (i != 0)
> -				printk("\n");
> +	for (pos = 0; pos < len; ++pos, ++i) {
> +		if (i == JFFS2_BUFDUMP_BYTES_PER_LINE) {
>  			offs += JFFS2_BUFDUMP_BYTES_PER_LINE;
> -			printk(JFFS2_DBG "%0#8x: ", offs);
> +			printk(JFFS2_DBG "\n%0#8x: ", offs);
> +			i = 0;

print_hex_dump would be better

Le 21/10/2014 10:17, Joe Perches a écrit :
> On Tue, 2014-10-21 at 10:05 +0200, Cyrille Pitchen wrote:
>> This patch fixes __jffs2_dbg_dump_buffer(): this function prints a message
>> claiming to dump len bytes. However, depending on the start offset, the former
>> code drops up to 31 (JFFS2_BUFDUMP_BYTES_PER_LINE - 1) bytes.
>>
>> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
>> ---
>>  fs/jffs2/debug.c | 21 ++++++++-------------
>>  1 file changed, 8 insertions(+), 13 deletions(-)
>>
>> diff --git a/fs/jffs2/debug.c b/fs/jffs2/debug.c
>> index 07bd5bc..1b515b2 100644
>> --- a/fs/jffs2/debug.c
>> +++ b/fs/jffs2/debug.c
>> @@ -736,30 +736,25 @@ void
>>  __jffs2_dbg_dump_buffer(unsigned char *buf, int len, uint32_t offs)
>>  {
>>  	int skip;
>> -	int i;
>> +	int i, pos;
>>  
>>  	printk(JFFS2_DBG_MSG_PREFIX " dump from offset %#08x to offset %#08x (%x bytes).\n",
>>  		offs, offs + len, len);
>> -	i = skip = offs % JFFS2_BUFDUMP_BYTES_PER_LINE;
>> +	i = skip = offs & (JFFS2_BUFDUMP_BYTES_PER_LINE - 1);
>>  	offs = offs & ~(JFFS2_BUFDUMP_BYTES_PER_LINE - 1);
>>  
>> -	if (skip != 0)
>> -		printk(JFFS2_DBG "%#08x: ", offs);
>> -
>> +	printk(JFFS2_DBG "%#08x: ", offs);
>>  	while (skip--)
>>  		printk("   ");
>>  
>> -	while (i < len) {
>> -		if ((i % JFFS2_BUFDUMP_BYTES_PER_LINE) == 0 && i != len -1) {
>> -			if (i != 0)
>> -				printk("\n");
>> +	for (pos = 0; pos < len; ++pos, ++i) {
>> +		if (i == JFFS2_BUFDUMP_BYTES_PER_LINE) {
>>  			offs += JFFS2_BUFDUMP_BYTES_PER_LINE;
>> -			printk(JFFS2_DBG "%0#8x: ", offs);
>> +			printk(JFFS2_DBG "\n%0#8x: ", offs);
>> +			i = 0;
> 
> print_hex_dump would be better
> 
> 
Hi Joe,

thanks for your comment. Indeed using print_hex_dump() would be a good idea
since it would avoid each driver to implement its own version of buffer dumps.
Reading the source code of print_hex_dump(), the output format would change a
little bit:
the output would no longer be aligned to JFFS2_BUFDUMP_BYTES_PER_LINE boundary
using leading spaces.
If it's ok to change the output format it's good for me as well.

On Tue, 2014-10-21 at 11:47 +0200, Cyrille Pitchen wrote:
> thanks for your comment. Indeed using print_hex_dump() would be a good idea
> since it would avoid each driver to implement its own version of buffer dumps.
> Reading the source code of print_hex_dump(), the output format would change a
> little bit:
> the output would no longer be aligned to JFFS2_BUFDUMP_BYTES_PER_LINE boundary
> using leading spaces.
> If it's ok to change the output format it's good for me as well.

Changing format is OK, this is just a debugging cruft. But it is OK only
if you test the changes. If you are unable to test the changes, it is
better to avoid doing non-trivial changes.

Le 21/10/2014 11:54, Artem Bityutskiy a écrit :
> On Tue, 2014-10-21 at 11:47 +0200, Cyrille Pitchen wrote:
>> thanks for your comment. Indeed using print_hex_dump() would be a good idea
>> since it would avoid each driver to implement its own version of buffer dumps.
>> Reading the source code of print_hex_dump(), the output format would change a
>> little bit:
>> the output would no longer be aligned to JFFS2_BUFDUMP_BYTES_PER_LINE boundary
>> using leading spaces.
>> If it's ok to change the output format it's good for me as well.
> 
> Changing format is OK, this is just a debugging cruft. But it is OK only
> if you test the changes. If you are unable to test the changes, it is
> better to avoid doing non-trivial changes.
> 
The version provided in this patch was tested. However I don't know how to cope
with the offs parameter of __jffs2_dbg_dump_buffer() if I replace the current
source code by a call to print_hex_dump().
If I use DUMP_PREFIX_ADDRESS as prefix_type value, the printed offsets are
relative to the address of buf in RAM, not to the hardware offset in my
dataflash provided by the offs parameter.
Also, if I use DUMP_PREFIX_OFFSET, the printed offsets start from 0 instead of
offs value.

I think keeping the right offsets in the output dump is helpfull.