Messages in this thread Patch in this message | | | From | Qiao Ma <> | Subject | [PATCH] net: hinic: avoid kernel hung in hinic_get_stats64() | Date | Wed, 29 Jun 2022 15:28:26 +0800 |
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When using hinic device as a bond slave device, and reading device stats of master bond device, the kernel may hung.
The kernel panic calltrace as follows: Kernel panic - not syncing: softlockup: hung tasks Call trace: native_queued_spin_lock_slowpath+0x1ec/0x31c dev_get_stats+0x60/0xcc dev_seq_printf_stats+0x40/0x120 dev_seq_show+0x1c/0x40 seq_read_iter+0x3c8/0x4dc seq_read+0xe0/0x130 proc_reg_read+0xa8/0xe0 vfs_read+0xb0/0x1d4 ksys_read+0x70/0xfc __arm64_sys_read+0x20/0x30 el0_svc_common+0x88/0x234 do_el0_svc+0x2c/0x90 el0_svc+0x1c/0x30 el0_sync_handler+0xa8/0xb0 el0_sync+0x148/0x180
And the calltrace of task that actually caused kernel hungs as follows: __switch_to+124 __schedule+548 schedule+72 schedule_timeout+348 __down_common+188 __down+24 down+104 hinic_get_stats64+44 [hinic] dev_get_stats+92 bond_get_stats+172 [bonding] dev_get_stats+92 dev_seq_printf_stats+60 dev_seq_show+24 seq_read_iter+964 seq_read+220 proc_reg_read+164 vfs_read+172 ksys_read+108 __arm64_sys_read+28 el0_svc_common+132 do_el0_svc+40 el0_svc+24 el0_sync_handler+164 el0_sync+324
When getting device stats from bond, kernel will call bond_get_stats(). It first holds the spinlock bond->stats_lock, and then call hinic_get_stats64() to collect hinic device's stats. However, hinic_get_stats64() calls `down(&nic_dev->mgmt_lock)` to protect its critical section, which may schedule current task out. And if system is under high pressure, the task cannot be woken up immediately, which eventually triggers kernel hung panic.
Fixes: edd384f682cc ("net-next/hinic: Add ethtool and stats") Signed-off-by: Qiao Ma <mqaio@linux.alibaba.com> --- drivers/net/ethernet/huawei/hinic/hinic_dev.h | 1 + drivers/net/ethernet/huawei/hinic/hinic_main.c | 7 +++---- 2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/huawei/hinic/hinic_dev.h b/drivers/net/ethernet/huawei/hinic/hinic_dev.h index fb3e89141a0d..1fb343d03fd5 100644 --- a/drivers/net/ethernet/huawei/hinic/hinic_dev.h +++ b/drivers/net/ethernet/huawei/hinic/hinic_dev.h @@ -97,6 +97,7 @@ struct hinic_dev { struct hinic_txq_stats tx_stats; struct hinic_rxq_stats rx_stats; + spinlock_t stats_lock; u8 rss_tmpl_idx; u8 rss_hash_engine; diff --git a/drivers/net/ethernet/huawei/hinic/hinic_main.c b/drivers/net/ethernet/huawei/hinic/hinic_main.c index 56a89793f47d..32a3d700ad26 100644 --- a/drivers/net/ethernet/huawei/hinic/hinic_main.c +++ b/drivers/net/ethernet/huawei/hinic/hinic_main.c @@ -125,11 +125,13 @@ static void update_nic_stats(struct hinic_dev *nic_dev) { int i, num_qps = hinic_hwdev_num_qps(nic_dev->hwdev); + spin_lock(&nic_dev->stats_lock); for (i = 0; i < num_qps; i++) update_rx_stats(nic_dev, &nic_dev->rxqs[i]); for (i = 0; i < num_qps; i++) update_tx_stats(nic_dev, &nic_dev->txqs[i]); + spin_unlock(&nic_dev->stats_lock); } /** @@ -859,13 +861,9 @@ static void hinic_get_stats64(struct net_device *netdev, nic_rx_stats = &nic_dev->rx_stats; nic_tx_stats = &nic_dev->tx_stats; - down(&nic_dev->mgmt_lock); - if (nic_dev->flags & HINIC_INTF_UP) update_nic_stats(nic_dev); - up(&nic_dev->mgmt_lock); - stats->rx_bytes = nic_rx_stats->bytes; stats->rx_packets = nic_rx_stats->pkts; stats->rx_errors = nic_rx_stats->errors; @@ -1239,6 +1237,7 @@ static int nic_dev_init(struct pci_dev *pdev) u64_stats_init(&tx_stats->syncp); u64_stats_init(&rx_stats->syncp); + spin_lock_init(&nic_dev->stats_lock); nic_dev->vlan_bitmap = devm_bitmap_zalloc(&pdev->dev, VLAN_N_VID, GFP_KERNEL); -- 1.8.3.1
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