drivers/net/ethernet/sfc/ethtool_common.c:170:32: warning: '%-24s' directive output may be truncated writing between 24 and 31 bytes into a region of size 25

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   a64dcfb451e254085a7daee5fe51bf22959d52d3
commit: 3653954da498fc80c5da3642ae3f8d8168d7f820 sfc: move some ethtool code
date:   5 years ago
config: x86_64-randconfig-001-20241126 (https://download.01.org/0day-ci/archive/20250210/202502102316.8R6hTLsF-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250210/202502102316.8R6hTLsF-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202502102316.8R6hTLsF-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/net/ethernet/sfc/ethtool_common.c:150:6: warning: no previous prototype for 'efx_fill_test' [-Wmissing-prototypes]
     150 | void efx_fill_test(unsigned int test_index, u8 *strings, u64 *data,
         |      ^~~~~~~~~~~~~
   drivers/net/ethernet/sfc/ethtool_common.c:192:5: warning: no previous prototype for 'efx_fill_loopback_test' [-Wmissing-prototypes]
     192 | int efx_fill_loopback_test(struct efx_nic *efx,
         |     ^~~~~~~~~~~~~~~~~~~~~~
   drivers/net/ethernet/sfc/ethtool_common.c:296:8: warning: no previous prototype for 'efx_describe_per_queue_stats' [-Wmissing-prototypes]
     296 | size_t efx_describe_per_queue_stats(struct efx_nic *efx, u8 *strings)
         |        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/net/ethernet/sfc/ethtool_common.c: In function 'efx_fill_test':
>> drivers/net/ethernet/sfc/ethtool_common.c:170:32: warning: '%-24s' directive output may be truncated writing between 24 and 31 bytes into a region of size 25 [-Wformat-truncation=]
     170 |                          "%-6s %-24s", unit_str, test_str);
         |                                ^~~~~             ~~~~~~~~
   drivers/net/ethernet/sfc/ethtool_common.c:168:17: note: 'snprintf' output 32 or more bytes (assuming 39) into a destination of size 32
     168 |                 snprintf(strings + test_index * ETH_GSTRING_LEN,
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     169 |                          ETH_GSTRING_LEN,
         |                          ~~~~~~~~~~~~~~~~
     170 |                          "%-6s %-24s", unit_str, test_str);
         |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +170 drivers/net/ethernet/sfc/ethtool_common.c

   136	
   137	/**
   138	 * efx_fill_test - fill in an individual self-test entry
   139	 * @test_index:		Index of the test
   140	 * @strings:		Ethtool strings, or %NULL
   141	 * @data:		Ethtool test results, or %NULL
   142	 * @test:		Pointer to test result (used only if data != %NULL)
   143	 * @unit_format:	Unit name format (e.g. "chan\%d")
   144	 * @unit_id:		Unit id (e.g. 0 for "chan0")
   145	 * @test_format:	Test name format (e.g. "loopback.\%s.tx.sent")
   146	 * @test_id:		Test id (e.g. "PHYXS" for "loopback.PHYXS.tx_sent")
   147	 *
   148	 * Fill in an individual self-test entry.
   149	 */
   150	void efx_fill_test(unsigned int test_index, u8 *strings, u64 *data,
   151			   int *test, const char *unit_format, int unit_id,
   152			   const char *test_format, const char *test_id)
   153	{
   154		char unit_str[ETH_GSTRING_LEN], test_str[ETH_GSTRING_LEN];
   155	
   156		/* Fill data value, if applicable */
   157		if (data)
   158			data[test_index] = *test;
   159	
   160		/* Fill string, if applicable */
   161		if (strings) {
   162			if (strchr(unit_format, '%'))
   163				snprintf(unit_str, sizeof(unit_str),
   164					 unit_format, unit_id);
   165			else
   166				strcpy(unit_str, unit_format);
   167			snprintf(test_str, sizeof(test_str), test_format, test_id);
   168			snprintf(strings + test_index * ETH_GSTRING_LEN,
   169				 ETH_GSTRING_LEN,
 > 170				 "%-6s %-24s", unit_str, test_str);
   171		}
   172	}
   173	

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