[PATCH V2 net 4/4] net: hns3: fix deadlock issue when externel_lb and reset are executed together

[Jijie Shao]

From: Yonglong Liu <liuyonglong@xxxxxxxxxx>

When externel_lb and reset are executed together, a deadlock may
occur:
[ 3147.217009] INFO: task kworker/u321:0:7 blocked for more than 120 seconds.
[ 3147.230483] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3147.238999] task:kworker/u321:0  state:D stack:    0 pid:    7 ppid:     2 flags:0x00000008
[ 3147.248045] Workqueue: hclge hclge_service_task [hclge]
[ 3147.253957] Call trace:
[ 3147.257093]  __switch_to+0x7c/0xbc
[ 3147.261183]  __schedule+0x338/0x6f0
[ 3147.265357]  schedule+0x50/0xe0
[ 3147.269185]  schedule_preempt_disabled+0x18/0x24
[ 3147.274488]  __mutex_lock.constprop.0+0x1d4/0x5dc
[ 3147.279880]  __mutex_lock_slowpath+0x1c/0x30
[ 3147.284839]  mutex_lock+0x50/0x60
[ 3147.288841]  rtnl_lock+0x20/0x2c
[ 3147.292759]  hclge_reset_prepare+0x68/0x90 [hclge]
[ 3147.298239]  hclge_reset_subtask+0x88/0xe0 [hclge]
[ 3147.303718]  hclge_reset_service_task+0x84/0x120 [hclge]
[ 3147.309718]  hclge_service_task+0x2c/0x70 [hclge]
[ 3147.315109]  process_one_work+0x1d0/0x490
[ 3147.319805]  worker_thread+0x158/0x3d0
[ 3147.324240]  kthread+0x108/0x13c
[ 3147.328154]  ret_from_fork+0x10/0x18

In externel_lb process, the hns3 driver call napi_disable()
first, then the reset happen, then the restore process of the
externel_lb will fail, and will not call napi_enable(). When
doing externel_lb again, napi_disable() will be double call,
cause a deadlock of rtnl_lock().

This patch use the HNS3_NIC_STATE_DOWN state to protect the
calling of napi_disable() and napi_enable() in externel_lb
process, just as the usage in ndo_stop() and ndo_start().

Fixes: 04b6ba143521 ("net: hns3: add support for external loopback test")
Signed-off-by: Yonglong Liu <liuyonglong@xxxxxxxxxx>
Signed-off-by: Jijie Shao <shaojijie@xxxxxxxxxx>
---
 drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index 9f6890059666..b7b51e56b030 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -5854,6 +5854,9 @@ void hns3_external_lb_prepare(struct net_device *ndev, bool if_running)
 	if (!if_running)
 		return;
 
+	if (test_and_set_bit(HNS3_NIC_STATE_DOWN, &priv->state))
+		return;
+
 	netif_carrier_off(ndev);
 	netif_tx_disable(ndev);
 
@@ -5882,7 +5885,16 @@ void hns3_external_lb_restore(struct net_device *ndev, bool if_running)
 	if (!if_running)
 		return;
 
-	hns3_nic_reset_all_ring(priv->ae_handle);
+	if (hns3_nic_resetting(ndev))
+		return;
+
+	if (!test_bit(HNS3_NIC_STATE_DOWN, &priv->state))
+		return;
+
+	if (hns3_nic_reset_all_ring(priv->ae_handle))
+		return;
+
+	clear_bit(HNS3_NIC_STATE_DOWN, &priv->state);
 
 	for (i = 0; i < priv->vector_num; i++)
 		hns3_vector_enable(&priv->tqp_vector[i]);
-- 
2.30.0