Hi,

[auto build test WARNING on v4.7-rc1]
[cannot apply to next-20160603]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/George-Spelvin/Clean-up-and-shrink-uuid-input-output/20160604-131729
config: x86_64-lkp (attached as .config)
compiler: gcc-4.9 (Debian 4.9.3-14) 4.9.3
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   lib/uuid.c: In function '__uuid_to_bin':
>> lib/uuid.c:107:3: warning: ignoring return value of 'hex2bin', declared with attribute warn_unused_result [-Wunused-result]
      hex2bin(b + i, uuid + pos[i], 1);
      ^

vim +/hex2bin +107 lib/uuid.c

    91		return true;
    92	}
    93	EXPORT_SYMBOL(uuid_is_valid);
    94	
    95	/* For each binary byte, string offset in ASCII UUID where it appears */
    96	const u8 uuid_be_pos[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
    97	const u8 uuid_le_pos[16] = {6,4,2,0,11,9,16,14,19,21,24,26,28,30,32,34};
    98	
    99	static int __uuid_to_bin(const char uuid[36], __u8 b[16], const u8 pos[16])
   100	{
   101		unsigned int i;
   102	
   103		if (!uuid_is_valid(uuid))
   104			return -EINVAL;
   105	
   106		for (i = 0; i < 16; i++)
 > 107			hex2bin(b + i, uuid + pos[i], 1);
   108	
   109		return 0;
   110	}
   111	
   112	int uuid_le_to_bin(const char *uuid, uuid_le *u)
   113	{
   114		return __uuid_to_bin(uuid, u->b, uuid_le_pos);
   115	}

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