Hi Xuan, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on net-next/main] url: https://github.com/intel-lab-lkp/linux/commits/Xuan-Zhuo/virtio_net-mergeable-xdp-put-old-page-immediately/20230322-110445 patch link: https://lore.kernel.org/r/20230322030308.16046-8-xuanzhuo%40linux.alibaba.com patch subject: [PATCH net-next 7/8] virtio_net: introduce receive_mergeable_xdp() config: i386-randconfig-a002 (https://download.01.org/0day-ci/archive/20230323/202303230720.XUavHilr-lkp@xxxxxxxxx/config) compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1) 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 # https://github.com/intel-lab-lkp/linux/commit/c00edb888e239eb9eb468c0e93419f373f5e72a7 git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Xuan-Zhuo/virtio_net-mergeable-xdp-put-old-page-immediately/20230322-110445 git checkout c00edb888e239eb9eb468c0e93419f373f5e72a7 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 olddefconfig COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/net/ If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Link: https://lore.kernel.org/oe-kbuild-all/202303230720.XUavHilr-lkp@xxxxxxxxx/ All warnings (new ones prefixed by >>): >> drivers/net/virtio_net.c:1399:6: warning: variable 'page' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (unlikely(len > truesize - room)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:78:22: note: expanded from macro 'unlikely' # define unlikely(x) __builtin_expect(!!(x), 0) ^~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:1490:11: note: uninitialized use occurs here put_page(page); ^~~~ drivers/net/virtio_net.c:1399:2: note: remove the 'if' if its condition is always false if (unlikely(len > truesize - room)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:1392:19: note: initialize the variable 'page' to silence this warning struct page *page; ^ = NULL >> drivers/net/virtio_net.c:1399:6: warning: variable 'num_buf' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (unlikely(len > truesize - room)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:78:22: note: expanded from macro 'unlikely' # define unlikely(x) __builtin_expect(!!(x), 0) ^~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:1491:25: note: uninitialized use occurs here mergeable_buf_free(rq, num_buf, dev, stats); ^~~~~~~ drivers/net/virtio_net.c:1399:2: note: remove the 'if' if its condition is always false if (unlikely(len > truesize - room)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/net/virtio_net.c:1393:13: note: initialize the variable 'num_buf' to silence this warning int num_buf; ^ = 0 2 warnings generated. vim +1399 drivers/net/virtio_net.c 1375 1376 static struct sk_buff *receive_mergeable(struct net_device *dev, 1377 struct virtnet_info *vi, 1378 struct receive_queue *rq, 1379 void *buf, 1380 void *ctx, 1381 unsigned int len, 1382 unsigned int *xdp_xmit, 1383 struct virtnet_rq_stats *stats) 1384 { 1385 unsigned int truesize = mergeable_ctx_to_truesize(ctx); 1386 unsigned int headroom = mergeable_ctx_to_headroom(ctx); 1387 unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0; 1388 unsigned int room = SKB_DATA_ALIGN(headroom + tailroom); 1389 struct virtio_net_hdr_mrg_rxbuf *hdr; 1390 struct sk_buff *head_skb, *curr_skb; 1391 struct bpf_prog *xdp_prog; 1392 struct page *page; 1393 int num_buf; 1394 int offset; 1395 1396 head_skb = NULL; 1397 stats->bytes += len - vi->hdr_len; 1398 > 1399 if (unlikely(len > truesize - room)) { 1400 pr_debug("%s: rx error: len %u exceeds truesize %lu\n", 1401 dev->name, len, (unsigned long)(truesize - room)); 1402 dev->stats.rx_length_errors++; 1403 goto err_skb; 1404 } 1405 1406 if (likely(vi->xdp_enabled)) { 1407 rcu_read_lock(); 1408 xdp_prog = rcu_dereference(rq->xdp_prog); 1409 if (xdp_prog) { 1410 head_skb = receive_mergeable_xdp(dev, vi, rq, xdp_prog, 1411 buf, ctx, len, xdp_xmit, 1412 stats); 1413 rcu_read_unlock(); 1414 return head_skb; 1415 } 1416 rcu_read_unlock(); 1417 } 1418 1419 hdr = buf; 1420 num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers); 1421 page = virt_to_head_page(buf); 1422 offset = buf - page_address(page); 1423 1424 head_skb = page_to_skb(vi, rq, page, offset, len, truesize, headroom); 1425 curr_skb = head_skb; 1426 1427 if (unlikely(!curr_skb)) 1428 goto err_skb; 1429 while (--num_buf) { 1430 int num_skb_frags; 1431 1432 buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx); 1433 if (unlikely(!buf)) { 1434 pr_debug("%s: rx error: %d buffers out of %d missing\n", 1435 dev->name, num_buf, 1436 virtio16_to_cpu(vi->vdev, 1437 hdr->num_buffers)); 1438 dev->stats.rx_length_errors++; 1439 goto err_buf; 1440 } 1441 1442 stats->bytes += len; 1443 page = virt_to_head_page(buf); 1444 1445 truesize = mergeable_ctx_to_truesize(ctx); 1446 headroom = mergeable_ctx_to_headroom(ctx); 1447 tailroom = headroom ? sizeof(struct skb_shared_info) : 0; 1448 room = SKB_DATA_ALIGN(headroom + tailroom); 1449 if (unlikely(len > truesize - room)) { 1450 pr_debug("%s: rx error: len %u exceeds truesize %lu\n", 1451 dev->name, len, (unsigned long)(truesize - room)); 1452 dev->stats.rx_length_errors++; 1453 goto err_skb; 1454 } 1455 1456 num_skb_frags = skb_shinfo(curr_skb)->nr_frags; 1457 if (unlikely(num_skb_frags == MAX_SKB_FRAGS)) { 1458 struct sk_buff *nskb = alloc_skb(0, GFP_ATOMIC); 1459 1460 if (unlikely(!nskb)) 1461 goto err_skb; 1462 if (curr_skb == head_skb) 1463 skb_shinfo(curr_skb)->frag_list = nskb; 1464 else 1465 curr_skb->next = nskb; 1466 curr_skb = nskb; 1467 head_skb->truesize += nskb->truesize; 1468 num_skb_frags = 0; 1469 } 1470 if (curr_skb != head_skb) { 1471 head_skb->data_len += len; 1472 head_skb->len += len; 1473 head_skb->truesize += truesize; 1474 } 1475 offset = buf - page_address(page); 1476 if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) { 1477 put_page(page); 1478 skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1, 1479 len, truesize); 1480 } else { 1481 skb_add_rx_frag(curr_skb, num_skb_frags, page, 1482 offset, len, truesize); 1483 } 1484 } 1485 1486 ewma_pkt_len_add(&rq->mrg_avg_pkt_len, head_skb->len); 1487 return head_skb; 1488 1489 err_skb: 1490 put_page(page); 1491 mergeable_buf_free(rq, num_buf, dev, stats); 1492 1493 err_buf: 1494 stats->drops++; 1495 dev_kfree_skb(head_skb); 1496 return NULL; 1497 } 1498 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests
