drivers/net/ethernet/mediatek/mtk_eth_soc.c:1481:23: warning: result of comparison of constant 65536 with expression of type 'u16' (aka 'unsigned short') is always true

kernel test robot
2023-02-02T17:45:51Z

head: 9f266ccaa2f5228bfe67ad58a94ca4e0109b954a
commit: 2f2c0d2919a14002760f89f4e02960c735a316d2 net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag
date: 8 months ago
config: arm64-randconfig-r005-20230202 (https://download.01.org/0day-ci/archive/20230203/202302030154.JHiHm9ZP-lkp@intel.com/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 4196ca3278f78c6e19246e54ab0ecb364e37d66a)
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 arm64 cross compiling tool for clang build
# apt-get install binutils-aarch64-linux-gnu
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2f2c0d2919a14002760f89f4e02960c735a316d2
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout 2f2c0d2919a14002760f89f4e02960c735a316d2
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash drivers/net/ethernet/mediatek/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> drivers/net/ethernet/mediatek/mtk_eth_soc.c:1481:23: warning: result of comparison of constant 65536 with expression of type 'u16' (aka 'unsigned short') is always true [-Wtautological-constant-out-of-range-compare]
if (ring->frag_size <= PAGE_SIZE)
~~~~~~~~~~~~~~~ ^ ~~~~~~~~~
drivers/net/ethernet/mediatek/mtk_eth_soc.c:1931:23: warning: result of comparison of constant 65536 with expression of type 'u16' (aka 'unsigned short') is always true [-Wtautological-constant-out-of-range-compare]
if (ring->frag_size <= PAGE_SIZE)
~~~~~~~~~~~~~~~ ^ ~~~~~~~~~
2 warnings generated.

vim +1481 drivers/net/ethernet/mediatek/mtk_eth_soc.c

1434
1435 static int mtk_poll_rx(struct napi_struct *napi, int budget,
1436 struct mtk_eth *eth)
1437 {
1438 struct dim_sample dim_sample = {};
1439 struct mtk_rx_ring *ring;
1440 int idx;
1441 struct sk_buff *skb;
1442 u8 *data, *new_data;
1443 struct mtk_rx_dma_v2 *rxd, trxd;
1444 int done = 0, bytes = 0;
1445
1446 while (done < budget) {
1447 struct net_device *netdev;
1448 unsigned int pktlen;
1449 dma_addr_t dma_addr;
1450 u32 hash, reason;
1451 int mac = 0;
1452
1453 ring = mtk_get_rx_ring(eth);
1454 if (unlikely(!ring))
1455 goto rx_done;
1456
1457 idx = NEXT_DESP_IDX(ring->calc_idx, ring->dma_size);
1458 rxd = ring->dma + idx * eth->soc->txrx.rxd_size;
1459 data = ring->data[idx];
1460
1461 if (!mtk_rx_get_desc(eth, &trxd, rxd))
1462 break;
1463
1464 /* find out which mac the packet come from. values start at 1 */
1465 if (MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2))
1466 mac = RX_DMA_GET_SPORT_V2(trxd.rxd5) - 1;
1467 else if (!MTK_HAS_CAPS(eth->soc->caps, MTK_SOC_MT7628) &&
1468 !(trxd.rxd4 & RX_DMA_SPECIAL_TAG))
1469 mac = RX_DMA_GET_SPORT(trxd.rxd4) - 1;
1470
1471 if (unlikely(mac < 0 || mac >= MTK_MAC_COUNT ||
1472 !eth->netdev[mac]))
1473 goto release_desc;
1474
1475 netdev = eth->netdev[mac];
1476
1477 if (unlikely(test_bit(MTK_RESETTING, &eth->state)))
1478 goto release_desc;
1479
1480 /* alloc new buffer */
> 1481 if (ring->frag_size <= PAGE_SIZE)
1482 new_data = napi_alloc_frag(ring->frag_size);
1483 else
1484 new_data = mtk_max_lro_buf_alloc(GFP_ATOMIC);
1485 if (unlikely(!new_data)) {
1486 netdev->stats.rx_dropped++;
1487 goto release_desc;
1488 }
1489 dma_addr = dma_map_single(eth->dma_dev,
1490 new_data + NET_SKB_PAD +
1491 eth->ip_align,
1492 ring->buf_size,
1493 DMA_FROM_DEVICE);
1494 if (unlikely(dma_mapping_error(eth->dma_dev, dma_addr))) {
1495 skb_free_frag(new_data);
1496 netdev->stats.rx_dropped++;
1497 goto release_desc;
1498 }
1499
1500 dma_unmap_single(eth->dma_dev, trxd.rxd1,
1501 ring->buf_size, DMA_FROM_DEVICE);
1502
1503 /* receive data */
1504 skb = build_skb(data, ring->frag_size);
1505 if (unlikely(!skb)) {
1506 skb_free_frag(data);
1507 netdev->stats.rx_dropped++;
1508 goto skip_rx;
1509 }
1510 skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
1511
1512 pktlen = RX_DMA_GET_PLEN0(trxd.rxd2);
1513 skb->dev = netdev;
1514 skb_put(skb, pktlen);
1515 if (trxd.rxd4 & eth->soc->txrx.rx_dma_l4_valid)
1516 skb->ip_summed = CHECKSUM_UNNECESSARY;
1517 else
1518 skb_checksum_none_assert(skb);
1519 skb->protocol = eth_type_trans(skb, netdev);
1520 bytes += pktlen;
1521
1522 hash = trxd.rxd4 & MTK_RXD4_FOE_ENTRY;
1523 if (hash != MTK_RXD4_FOE_ENTRY) {
1524 hash = jhash_1word(hash, 0);
1525 skb_set_hash(skb, hash, PKT_HASH_TYPE_L4);
1526 }
1527
1528 reason = FIELD_GET(MTK_RXD4_PPE_CPU_REASON, trxd.rxd4);
1529 if (reason == MTK_PPE_CPU_REASON_HIT_UNBIND_RATE_REACHED)
1530 mtk_ppe_check_skb(eth->ppe, skb,
1531 trxd.rxd4 & MTK_RXD4_FOE_ENTRY);
1532
1533 if (netdev->features & NETIF_F_HW_VLAN_CTAG_RX) {
1534 if (MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2)) {
1535 if (trxd.rxd3 & RX_DMA_VTAG_V2)
1536 __vlan_hwaccel_put_tag(skb,
1537 htons(RX_DMA_VPID(trxd.rxd4)),
1538 RX_DMA_VID(trxd.rxd4));
1539 } else if (trxd.rxd2 & RX_DMA_VTAG) {
1540 __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
1541 RX_DMA_VID(trxd.rxd3));
1542 }
1543
1544 /* If the device is attached to a dsa switch, the special
1545 * tag inserted in VLAN field by hw switch can * be offloaded
1546 * by RX HW VLAN offload. Clear vlan info.
1547 */
1548 if (netdev_uses_dsa(netdev))
1549 __vlan_hwaccel_clear_tag(skb);
1550 }
1551
1552 skb_record_rx_queue(skb, 0);
1553 napi_gro_receive(napi, skb);
1554
1555 skip_rx:
1556 ring->data[idx] = new_data;
1557 rxd->rxd1 = (unsigned int)dma_addr;
1558
1559 release_desc:
1560 if (MTK_HAS_CAPS(eth->soc->caps, MTK_SOC_MT7628))
1561 rxd->rxd2 = RX_DMA_LSO;
1562 else
1563 rxd->rxd2 = RX_DMA_PREP_PLEN0(ring->buf_size);
1564
1565 ring->calc_idx = idx;
1566
1567 done++;
1568 }
1569
1570 rx_done:
1571 if (done) {
1572 /* make sure that all changes to the dma ring are flushed before
1573 * we continue
1574 */
1575 wmb();
1576 mtk_update_rx_cpu_idx(eth);
1577 }
1578
1579 eth->rx_packets += done;
1580 eth->rx_bytes += bytes;
1581 dim_update_sample(eth->rx_events, eth->rx_packets, eth->rx_bytes,
1582 &dim_sample);
1583 net_dim(&eth->rx_dim, dim_sample);
1584
1585 return done;
1586 }
1587

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