[PATCH 3/3] net: stmmac: use pcpu statistics where necessary

[kernel test robot]

Hi Jisheng,

kernel test robot noticed the following build warnings:

[auto build test WARNING on sunxi/sunxi/for-next]
[also build test WARNING on linus/master v6.4-rc6]
[cannot apply to next-20230614]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jisheng-Zhang/net-stmmac-don-t-clear-network-statistics-in-ndo_open/20230615-003137
base:   https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux.git sunxi/for-next
patch link:    https://lore.kernel.org/r/20230614161847.4071-4-jszhang%40kernel.org
patch subject: [PATCH 3/3] net: stmmac: use pcpu statistics where necessary
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20230615/202306150255.k4BaJTXY-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 12.3.0
reproduce (this is a W=1 build):
        mkdir -p ~/bin
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git remote add sunxi https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux.git
        git fetch sunxi sunxi/for-next
        git checkout sunxi/sunxi/for-next
        b4 shazam https://lore.kernel.org/r/20230614161847.4071-4-jszhang@kernel.org
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=m68k olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash drivers/net/

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 at intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306150255.k4BaJTXY-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c: In function 'stmmac_get_per_qstats':
>> drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c:564:26: warning: 'start' is used uninitialized [-Wuninitialized]
     564 |                 } while (u64_stats_fetch_retry(&stats->syncp, start));
         |                          ^~~~~~~~~~~~~~~~~~~~~
   drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c:551:22: note: 'start' was declared here
     551 |         unsigned int start;
         |                      ^~~~~


vim +/start +564 drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c

   546	
   547	static void stmmac_get_per_qstats(struct stmmac_priv *priv, u64 *data)
   548	{
   549		u32 tx_cnt = priv->plat->tx_queues_to_use;
   550		u32 rx_cnt = priv->plat->rx_queues_to_use;
   551		unsigned int start;
   552		int q, stat, cpu;
   553		char *p;
   554		u64 *pos;
   555	
   556		pos = data;
   557		for_each_possible_cpu(cpu) {
   558			struct stmmac_pcpu_stats *stats, snapshot;
   559	
   560			data = pos;
   561			stats = per_cpu_ptr(priv->xstats.pstats, cpu);
   562			do {
   563				snapshot = *stats;
 > 564			} while (u64_stats_fetch_retry(&stats->syncp, start));
   565	
   566			for (q = 0; q < tx_cnt; q++) {
   567				p = (char *)&snapshot + offsetof(struct stmmac_pcpu_stats,
   568							    txq_stats[q].tx_pkt_n);
   569				for (stat = 0; stat < STMMAC_TXQ_STATS; stat++) {
   570					*data++ = (*(u64 *)p);
   571					p += sizeof(u64);
   572				}
   573			}
   574			for (q = 0; q < rx_cnt; q++) {
   575				p = (char *)&snapshot + offsetof(struct stmmac_pcpu_stats,
   576							    rxq_stats[q].rx_pkt_n);
   577				for (stat = 0; stat < STMMAC_RXQ_STATS; stat++) {
   578					*data++ = (*(u64 *)p);
   579					p += sizeof(u64);
   580				}
   581			}
   582		}
   583	}
   584	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki