Re: [PATCH for-4.14 v2] tools/xen-ucode: fix error code propagation of microcode load operation

[Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>]

On 16/06/2020 13:25, Jan Beulich wrote:
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> On 16.06.2020 13:42, Igor Druzhinin wrote:
>> @@ -62,8 +62,11 @@ int main(int argc, char *argv[])
>>  
>>      ret = xc_microcode_update(xch, buf, len);
>>      if ( ret )
>> +    {
>>          fprintf(stderr, "Failed to update microcode. (err: %s)\n",
>>                  strerror(errno));
>> +        return errno;
> 
> I think you need to latch errno, as fprintf() may in principle run
> into another error.

Yes, I also noticed that but the whole file has this problem so I didn't
change it here specifically.

If fixing the whole file - I'd rather rewrite error reporting completely:
return 1 on error, 0 on success, etc. From what I've read returning errno
has many incompatibilities and might lead to surprise consequences.

I'll send v3 to clean this all up.

Igor