[PATCH] drm/amdgpu: Add double-sscanf but invert

[Luben Tuikov]

Yeah, %i would do, and certainly more elegant, except
for the signed input. Not sure if that's a problem, either,
thus the two sscanf...

Regards,
Luben

On 2021-04-14 11:58 a.m., Felix Kuehling wrote:
> From the sscanf manpage:
> 
>        i      Matches  an optionally signed integer; the next pointer
> must be
>               a pointer to int.  The integer is read in base 16 if it 
> begins
>               with  0x  or  0X, in base 8 if it begins with 0, and in
> base 10
>               otherwise.  Only characters that correspond  to  the 
> base  are
>               used.
> 
> So a single sscanf("%*s %i", ...) would to the job. The only problem is
> that accepts signed integers, not unsigned. I'm not sure if that's a
> problem in this use case.
> 
> Regards,
>   Felix
> 
> Am 2021-04-14 um 11:21 a.m. schrieb Luben Tuikov:
>> Add back the double-sscanf so that both decimal
>> and hexadecimal values could be read in, but this
>> time invert the scan so that hexadecimal format
>> with a leading 0x is tried first, and if that
>> fails, then try decimal format.
>>
>> Also use a logical-AND instead of nesting double
>> if-conditional.
>>
>> See commit "drm/amdgpu: Fix a bug for input with double sscanf"
>>
>> Cc: Alexander Deucher <Alexander.Deucher at amd.com>
>> Cc: John Clements <john.clements at amd.com>
>> Cc: Hawking Zhang <Hawking.Zhang at amd.com>
>> Signed-off-by: Luben Tuikov <luben.tuikov at amd.com>
>> ---
>>  drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
>> index 44dfb3613e37..38a691a3b600 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
>> @@ -229,7 +229,8 @@ static int amdgpu_ras_debugfs_ctrl_parse_data(struct file *f,
>>  
>>  	if (op != -1) {
>>  		if (op == 3) {
>> -			if (sscanf(str, "%*s %llx", &address) != 1)
>> +			if (sscanf(str, "%*s 0x%llx", &address) != 1 &&
>> +			    sscanf(str, "%*s %llu", &address) != 1)
>>  				return -EINVAL;
>>  
>>  			data->op = op;
>> @@ -253,7 +254,9 @@ static int amdgpu_ras_debugfs_ctrl_parse_data(struct file *f,
>>  		data->op = op;
>>  
>>  		if (op == 2) {
>> -			if (sscanf(str, "%*s %*s %*s %x %llx %llx",
>> +			if (sscanf(str, "%*s %*s %*s 0x%x 0x%llx 0x%llx",
>> +				   &sub_block, &address, &value) != 3 &&
>> +			    sscanf(str, "%*s %*s %*s %u %llu %llu",
>>  				   &sub_block, &address, &value) != 3)
>>  				return -EINVAL;
>>  			data->head.sub_block_index = sub_block;