Hi Xuan, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on net-next/master] url: https://github.com/0day-ci/linux/commits/Xuan-Zhuo/virtio-net-support-xdp... base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git c7654495916e109f76a67fd3ae68f8fa70ab4faa config: x86_64-randconfig-a015-20210617 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 64720f57bea6a6bf033feef4a5751ab9c0c3b401) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu # https://github.com/0day-ci/linux/commit/f5f1e60139e7c38fbb4ed58d503e89bbb... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Xuan-Zhuo/virtio-net-support-xdp-socket-zero-copy/20210617-033438 git checkout f5f1e60139e7c38fbb4ed58d503e89bbb26c1464 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): if (fill_recv_xsk(vi, rq, gfp)) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:56:28: note: expanded from macro 'if' #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) ) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:58:30: note: expanded from macro '__trace_if_var' #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond)) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio/virtio_net.c:1329:10: note: uninitialized use occurs here return !oom; ^~~ drivers/net/virtio/virtio_net.c:1304:2: note: remove the 'if' if its condition is always false if (fill_recv_xsk(vi, rq, gfp)) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:56:23: note: expanded from macro 'if' #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) ) ^ drivers/net/virtio/virtio_net.c:1297:10: note: initialize the variable 'oom' to silence this warning bool oom; ^ = 0 1 warning generated. vim +1304 drivers/net/virtio/virtio_net.c 1285 1286 /* 1287 * Returns false if we couldn't fill entirely (OOM). 1288 * 1289 * Normally run in the receive path, but can also be run from ndo_open 1290 * before we're receiving packets, or from refill_work which is 1291 * careful to disable receiving (using napi_disable). 1292 */ 1293 static bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq, 1294 gfp_t gfp) 1295 { 1296 int err; 1297 bool oom; 1298 1299 /* Because virtio-net does not yet support flow direct, all rx 1300 * channels must also process other non-xsk packets. If there is 1301 * no buf available from xsk temporarily, we try to allocate 1302 * memory to the channel. 1303 */ 1305 goto kick; 1306 1307 do { 1308 if (vi->mergeable_rx_bufs) 1309 err = add_recvbuf_mergeable(vi, rq, gfp); 1310 else if (vi->big_packets) 1311 err = add_recvbuf_big(vi, rq, gfp); 1312 else 1313 err = add_recvbuf_small(vi, rq, gfp); 1314 1315 oom = err == -ENOMEM; 1316 if (err) 1317 break; 1318 } while (rq->vq->num_free); 1319 1320 kick: 1321 if (virtqueue_kick_prepare(rq->vq) && virtqueue_notify(rq->vq)) { 1322 unsigned long flags; 1323 1324 flags = u64_stats_update_begin_irqsave(&rq->stats.syncp); 1325 rq->stats.kicks++; 1326 u64_stats_update_end_irqrestore(&rq->stats.syncp, flags); 1327 } 1328 1329 return !oom; 1330 } 1331 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org