Date:   Thu, 15 Dec 2022 23:50:48 +0100
From:   Michal Schmidt <mschmidt@...hat.com>
To:     intel-wired-lan@...ts.osuosl.org
Cc:     Ivan Vecera <ivecera@...hat.com>, netdev@...r.kernel.org,
        Mateusz Palczewski <mateusz.palczewski@...el.com>,
        Patryk Piotrowski <patryk.piotrowski@...el.com>
Subject: [PATCH net 1/2] iavf: fix temporary deadlock and failure to set MAC address

We are seeing an issue where setting the MAC address on iavf fails with
EAGAIN after the 2.5s timeout expires in iavf_set_mac().

There is the following deadlock scenario:

iavf_set_mac(), holding rtnl_lock, waits on:
  iavf_watchdog_task (within iavf_wq) to send a message to the PF,
 and
  iavf_adminq_task (within iavf_wq) to receive a response from the PF.
In this adapter state (>=__IAVF_DOWN), these tasks do not need to take
rtnl_lock, but iavf_wq is a global single-threaded workqueue, so they
may get stuck waiting for another adapter's iavf_watchdog_task to run
iavf_init_config_adapter(), which does take rtnl_lock.

The deadlock resolves itself by the timeout in iavf_set_mac(),
which results in EAGAIN returned to userspace.

Let's break the deadlock loop by changing iavf_wq into a per-adapter
workqueue, so that one adapter's tasks are not blocked by another's.

Fixes: 35a2443d0910 ("iavf: Add waiting for response from PF in set mac")
Co-developed-by: Ivan Vecera <ivecera@...hat.com>
Signed-off-by: Ivan Vecera <ivecera@...hat.com>
Signed-off-by: Michal Schmidt <mschmidt@...hat.com>
---
 drivers/net/ethernet/intel/iavf/iavf.h        |  2 +-
 .../net/ethernet/intel/iavf/iavf_ethtool.c    | 10 +--
 drivers/net/ethernet/intel/iavf/iavf_main.c   | 86 +++++++++----------
 .../net/ethernet/intel/iavf/iavf_virtchnl.c   |  2 +-
 4 files changed, 49 insertions(+), 51 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf.h b/drivers/net/ethernet/intel/iavf/iavf.h
index 0d1bab4ac1b0..2a9f1eeeb701 100644
--- a/drivers/net/ethernet/intel/iavf/iavf.h
+++ b/drivers/net/ethernet/intel/iavf/iavf.h
@@ -249,6 +249,7 @@ struct iavf_cloud_filter {
 
 /* board specific private data structure */
 struct iavf_adapter {
+	struct workqueue_struct *wq;
 	struct work_struct reset_task;
 	struct work_struct adminq_task;
 	struct delayed_work client_task;
@@ -459,7 +460,6 @@ struct iavf_device {
 
 /* needed by iavf_ethtool.c */
 extern char iavf_driver_name[];
-extern struct workqueue_struct *iavf_wq;
 
 static inline const char *iavf_state_str(enum iavf_state_t state)
 {
diff --git a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
index a056e1545615..83cfc54a4706 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
@@ -532,7 +532,7 @@ static int iavf_set_priv_flags(struct net_device *netdev, u32 flags)
 	if (changed_flags & IAVF_FLAG_LEGACY_RX) {
 		if (netif_running(netdev)) {
 			adapter->flags |= IAVF_FLAG_RESET_NEEDED;
-			queue_work(iavf_wq, &adapter->reset_task);
+			queue_work(adapter->wq, &adapter->reset_task);
 		}
 	}
 
@@ -672,7 +672,7 @@ static int iavf_set_ringparam(struct net_device *netdev,
 
 	if (netif_running(netdev)) {
 		adapter->flags |= IAVF_FLAG_RESET_NEEDED;
-		queue_work(iavf_wq, &adapter->reset_task);
+		queue_work(adapter->wq, &adapter->reset_task);
 	}
 
 	return 0;
@@ -1433,7 +1433,7 @@ static int iavf_add_fdir_ethtool(struct iavf_adapter *adapter, struct ethtool_rx
 	adapter->aq_required |= IAVF_FLAG_AQ_ADD_FDIR_FILTER;
 	spin_unlock_bh(&adapter->fdir_fltr_lock);
 
-	mod_delayed_work(iavf_wq, &adapter->watchdog_task, 0);
+	mod_delayed_work(adapter->wq, &adapter->watchdog_task, 0);
 
 ret:
 	if (err && fltr)
@@ -1474,7 +1474,7 @@ static int iavf_del_fdir_ethtool(struct iavf_adapter *adapter, struct ethtool_rx
 	spin_unlock_bh(&adapter->fdir_fltr_lock);
 
 	if (fltr && fltr->state == IAVF_FDIR_FLTR_DEL_REQUEST)
-		mod_delayed_work(iavf_wq, &adapter->watchdog_task, 0);
+		mod_delayed_work(adapter->wq, &adapter->watchdog_task, 0);
 
 	return err;
 }
@@ -1658,7 +1658,7 @@ iavf_set_adv_rss_hash_opt(struct iavf_adapter *adapter,
 	spin_unlock_bh(&adapter->adv_rss_lock);
 
 	if (!err)
-		mod_delayed_work(iavf_wq, &adapter->watchdog_task, 0);
+		mod_delayed_work(adapter->wq, &adapter->watchdog_task, 0);
 
 	mutex_unlock(&adapter->crit_lock);
 
diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
index f71e132ede09..e7380f1b4acc 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_main.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
@@ -49,7 +49,6 @@ MODULE_DESCRIPTION("Intel(R) Ethernet Adaptive Virtual Function Network Driver")
 MODULE_LICENSE("GPL v2");
 
 static const struct net_device_ops iavf_netdev_ops;
-struct workqueue_struct *iavf_wq;
 
 int iavf_status_to_errno(enum iavf_status status)
 {
@@ -277,7 +276,7 @@ void iavf_schedule_reset(struct iavf_adapter *adapter)
 	if (!(adapter->flags &
 	      (IAVF_FLAG_RESET_PENDING | IAVF_FLAG_RESET_NEEDED))) {
 		adapter->flags |= IAVF_FLAG_RESET_NEEDED;
-		queue_work(iavf_wq, &adapter->reset_task);
+		queue_work(adapter->wq, &adapter->reset_task);
 	}
 }
 
@@ -291,7 +290,7 @@ void iavf_schedule_reset(struct iavf_adapter *adapter)
 void iavf_schedule_request_stats(struct iavf_adapter *adapter)
 {
 	adapter->aq_required |= IAVF_FLAG_AQ_REQUEST_STATS;
-	mod_delayed_work(iavf_wq, &adapter->watchdog_task, 0);
+	mod_delayed_work(adapter->wq, &adapter->watchdog_task, 0);
 }
 
 /**
@@ -411,7 +410,7 @@ static irqreturn_t iavf_msix_aq(int irq, void *data)
 
 	if (adapter->state != __IAVF_REMOVE)
 		/* schedule work on the private workqueue */
-		queue_work(iavf_wq, &adapter->adminq_task);
+		queue_work(adapter->wq, &adapter->adminq_task);
 
 	return IRQ_HANDLED;
 }
@@ -1034,7 +1033,7 @@ int iavf_replace_primary_mac(struct iavf_adapter *adapter,
 
 	/* schedule the watchdog task to immediately process the request */
 	if (f) {
-		queue_work(iavf_wq, &adapter->watchdog_task.work);
+		queue_work(adapter->wq, &adapter->watchdog_task.work);
 		return 0;
 	}
 	return -ENOMEM;
@@ -1257,7 +1256,7 @@ static void iavf_up_complete(struct iavf_adapter *adapter)
 	adapter->aq_required |= IAVF_FLAG_AQ_ENABLE_QUEUES;
 	if (CLIENT_ENABLED(adapter))
 		adapter->flags |= IAVF_FLAG_CLIENT_NEEDS_OPEN;
-	mod_delayed_work(iavf_wq, &adapter->watchdog_task, 0);
+	mod_delayed_work(adapter->wq, &adapter->watchdog_task, 0);
 }
 
 /**
@@ -1414,7 +1413,7 @@ void iavf_down(struct iavf_adapter *adapter)
 		adapter->aq_required |= IAVF_FLAG_AQ_DISABLE_QUEUES;
 	}
 
-	mod_delayed_work(iavf_wq, &adapter->watchdog_task, 0);
+	mod_delayed_work(adapter->wq, &adapter->watchdog_task, 0);
 }
 
 /**
@@ -2248,7 +2247,7 @@ iavf_set_vlan_offload_features(struct iavf_adapter *adapter,
 
 	if (aq_required) {
 		adapter->aq_required |= aq_required;
-		mod_delayed_work(iavf_wq, &adapter->watchdog_task, 0);
+		mod_delayed_work(adapter->wq, &adapter->watchdog_task, 0);
 	}
 }
 
@@ -2700,7 +2699,7 @@ static void iavf_watchdog_task(struct work_struct *work)
 		adapter->aq_required = 0;
 		adapter->current_op = VIRTCHNL_OP_UNKNOWN;
 		mutex_unlock(&adapter->crit_lock);
-		queue_work(iavf_wq, &adapter->reset_task);
+		queue_work(adapter->wq, &adapter->reset_task);
 		return;
 	}
 
@@ -2708,31 +2707,31 @@ static void iavf_watchdog_task(struct work_struct *work)
 	case __IAVF_STARTUP:
 		iavf_startup(adapter);
 		mutex_unlock(&adapter->crit_lock);
-		queue_delayed_work(iavf_wq, &adapter->watchdog_task,
+		queue_delayed_work(adapter->wq, &adapter->watchdog_task,
 				   msecs_to_jiffies(30));
 		return;
 	case __IAVF_INIT_VERSION_CHECK:
 		iavf_init_version_check(adapter);
 		mutex_unlock(&adapter->crit_lock);
-		queue_delayed_work(iavf_wq, &adapter->watchdog_task,
+		queue_delayed_work(adapter->wq, &adapter->watchdog_task,
 				   msecs_to_jiffies(30));
 		return;
 	case __IAVF_INIT_GET_RESOURCES:
 		iavf_init_get_resources(adapter);
 		mutex_unlock(&adapter->crit_lock);
-		queue_delayed_work(iavf_wq, &adapter->watchdog_task,
+		queue_delayed_work(adapter->wq, &adapter->watchdog_task,
 				   msecs_to_jiffies(1));
 		return;
 	case __IAVF_INIT_EXTENDED_CAPS:
 		iavf_init_process_extended_caps(adapter);
 		mutex_unlock(&adapter->crit_lock);
-		queue_delayed_work(iavf_wq, &adapter->watchdog_task,
+		queue_delayed_work(adapter->wq, &adapter->watchdog_task,
 				   msecs_to_jiffies(1));
 		return;
 	case __IAVF_INIT_CONFIG_ADAPTER:
 		iavf_init_config_adapter(adapter);
 		mutex_unlock(&adapter->crit_lock);
-		queue_delayed_work(iavf_wq, &adapter->watchdog_task,
+		queue_delayed_work(adapter->wq, &adapter->watchdog_task,
 				   msecs_to_jiffies(1));
 		return;
 	case __IAVF_INIT_FAILED:
@@ -2751,14 +2750,14 @@ static void iavf_watchdog_task(struct work_struct *work)
 			adapter->flags |= IAVF_FLAG_PF_COMMS_FAILED;
 			iavf_shutdown_adminq(hw);
 			mutex_unlock(&adapter->crit_lock);
-			queue_delayed_work(iavf_wq,
+			queue_delayed_work(adapter->wq,
 					   &adapter->watchdog_task, (5 * HZ));
 			return;
 		}
 		/* Try again from failed step*/
 		iavf_change_state(adapter, adapter->last_state);
 		mutex_unlock(&adapter->crit_lock);
-		queue_delayed_work(iavf_wq, &adapter->watchdog_task, HZ);
+		queue_delayed_work(adapter->wq, &adapter->watchdog_task, HZ);
 		return;
 	case __IAVF_COMM_FAILED:
 		if (test_bit(__IAVF_IN_REMOVE_TASK,
@@ -2789,13 +2788,14 @@ static void iavf_watchdog_task(struct work_struct *work)
 		adapter->aq_required = 0;
 		adapter->current_op = VIRTCHNL_OP_UNKNOWN;
 		mutex_unlock(&adapter->crit_lock);
-		queue_delayed_work(iavf_wq,
+		queue_delayed_work(adapter->wq,
 				   &adapter->watchdog_task,
 				   msecs_to_jiffies(10));
 		return;
 	case __IAVF_RESETTING:
 		mutex_unlock(&adapter->crit_lock);
-		queue_delayed_work(iavf_wq, &adapter->watchdog_task, HZ * 2);
+		queue_delayed_work(adapter->wq, &adapter->watchdog_task,
+				   HZ * 2);
 		return;
 	case __IAVF_DOWN:
 	case __IAVF_DOWN_PENDING:
@@ -2834,9 +2834,9 @@ static void iavf_watchdog_task(struct work_struct *work)
 		adapter->aq_required = 0;
 		adapter->current_op = VIRTCHNL_OP_UNKNOWN;
 		dev_err(&adapter->pdev->dev, "Hardware reset detected\n");
-		queue_work(iavf_wq, &adapter->reset_task);
+		queue_work(adapter->wq, &adapter->reset_task);
 		mutex_unlock(&adapter->crit_lock);
-		queue_delayed_work(iavf_wq,
+		queue_delayed_work(adapter->wq,
 				   &adapter->watchdog_task, HZ * 2);
 		return;
 	}
@@ -2845,12 +2845,13 @@ static void iavf_watchdog_task(struct work_struct *work)
 	mutex_unlock(&adapter->crit_lock);
 restart_watchdog:
 	if (adapter->state >= __IAVF_DOWN)
-		queue_work(iavf_wq, &adapter->adminq_task);
+		queue_work(adapter->wq, &adapter->adminq_task);
 	if (adapter->aq_required)
-		queue_delayed_work(iavf_wq, &adapter->watchdog_task,
+		queue_delayed_work(adapter->wq, &adapter->watchdog_task,
 				   msecs_to_jiffies(20));
 	else
-		queue_delayed_work(iavf_wq, &adapter->watchdog_task, HZ * 2);
+		queue_delayed_work(adapter->wq, &adapter->watchdog_task,
+				   HZ * 2);
 }
 
 /**
@@ -2952,7 +2953,7 @@ static void iavf_reset_task(struct work_struct *work)
 	 */
 	if (!mutex_trylock(&adapter->crit_lock)) {
 		if (adapter->state != __IAVF_REMOVE)
-			queue_work(iavf_wq, &adapter->reset_task);
+			queue_work(adapter->wq, &adapter->reset_task);
 
 		goto reset_finish;
 	}
@@ -3116,7 +3117,7 @@ static void iavf_reset_task(struct work_struct *work)
 	bitmap_clear(adapter->vsi.active_cvlans, 0, VLAN_N_VID);
 	bitmap_clear(adapter->vsi.active_svlans, 0, VLAN_N_VID);
 
-	mod_delayed_work(iavf_wq, &adapter->watchdog_task, 2);
+	mod_delayed_work(adapter->wq, &adapter->watchdog_task, 2);
 
 	/* We were running when the reset started, so we need to restore some
 	 * state here.
@@ -3208,7 +3209,7 @@ static void iavf_adminq_task(struct work_struct *work)
 		if (adapter->state == __IAVF_REMOVE)
 			return;
 
-		queue_work(iavf_wq, &adapter->adminq_task);
+		queue_work(adapter->wq, &adapter->adminq_task);
 		goto out;
 	}
 
@@ -4349,7 +4350,7 @@ static int iavf_change_mtu(struct net_device *netdev, int new_mtu)
 
 	if (netif_running(netdev)) {
 		adapter->flags |= IAVF_FLAG_RESET_NEEDED;
-		queue_work(iavf_wq, &adapter->reset_task);
+		queue_work(adapter->wq, &adapter->reset_task);
 	}
 
 	return 0;
@@ -4898,6 +4899,13 @@ static int iavf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	hw = &adapter->hw;
 	hw->back = adapter;
 
+	adapter->wq = alloc_ordered_workqueue("%s", WQ_MEM_RECLAIM,
+					      iavf_driver_name);
+	if (!adapter->wq) {
+		err = -ENOMEM;
+		goto err_alloc_wq;
+	}
+
 	adapter->msg_enable = BIT(DEFAULT_DEBUG_LEVEL_SHIFT) - 1;
 	iavf_change_state(adapter, __IAVF_STARTUP);
 
@@ -4942,7 +4950,7 @@ static int iavf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	INIT_WORK(&adapter->adminq_task, iavf_adminq_task);
 	INIT_DELAYED_WORK(&adapter->watchdog_task, iavf_watchdog_task);
 	INIT_DELAYED_WORK(&adapter->client_task, iavf_client_task);
-	queue_delayed_work(iavf_wq, &adapter->watchdog_task,
+	queue_delayed_work(adapter->wq, &adapter->watchdog_task,
 			   msecs_to_jiffies(5 * (pdev->devfn & 0x07)));
 
 	/* Setup the wait queue for indicating transition to down status */
@@ -4954,6 +4962,8 @@ static int iavf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	return 0;
 
 err_ioremap:
+	destroy_workqueue(adapter->wq);
+err_alloc_wq:
 	free_netdev(netdev);
 err_alloc_etherdev:
 	pci_disable_pcie_error_reporting(pdev);
@@ -5023,7 +5033,7 @@ static int __maybe_unused iavf_resume(struct device *dev_d)
 		return err;
 	}
 
-	queue_work(iavf_wq, &adapter->reset_task);
+	queue_work(adapter->wq, &adapter->reset_task);
 
 	netif_device_attach(adapter->netdev);
 
@@ -5170,6 +5180,8 @@ static void iavf_remove(struct pci_dev *pdev)
 	}
 	spin_unlock_bh(&adapter->adv_rss_lock);
 
+	destroy_workqueue(adapter->wq);
+
 	free_netdev(netdev);
 
 	pci_disable_pcie_error_reporting(pdev);
@@ -5196,24 +5208,11 @@ static struct pci_driver iavf_driver = {
  **/
 static int __init iavf_init_module(void)
 {
-	int ret;
-
 	pr_info("iavf: %s\n", iavf_driver_string);
 
 	pr_info("%s\n", iavf_copyright);
 
-	iavf_wq = alloc_workqueue("%s", WQ_UNBOUND | WQ_MEM_RECLAIM, 1,
-				  iavf_driver_name);
-	if (!iavf_wq) {
-		pr_err("%s: Failed to create workqueue\n", iavf_driver_name);
-		return -ENOMEM;
-	}
-
-	ret = pci_register_driver(&iavf_driver);
-	if (ret)
-		destroy_workqueue(iavf_wq);
-
-	return ret;
+	return pci_register_driver(&iavf_driver);
 }
 
 module_init(iavf_init_module);
@@ -5227,7 +5226,6 @@ module_init(iavf_init_module);
 static void __exit iavf_exit_module(void)
 {
 	pci_unregister_driver(&iavf_driver);
-	destroy_workqueue(iavf_wq);
 }
 
 module_exit(iavf_exit_module);
diff --git a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
index 24a701fd140e..0752fd67c96e 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
@@ -1952,7 +1952,7 @@ void iavf_virtchnl_completion(struct iavf_adapter *adapter,
 			if (!(adapter->flags & IAVF_FLAG_RESET_PENDING)) {
 				adapter->flags |= IAVF_FLAG_RESET_PENDING;
 				dev_info(&adapter->pdev->dev, "Scheduling reset task\n");
-				queue_work(iavf_wq, &adapter->reset_task);
+				queue_work(adapter->wq, &adapter->reset_task);
 			}
 			break;
 		default:
-- 
2.37.2

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