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Date:   Mon,  9 Mar 2020 19:00:58 -0500
From:   Juliet Kim <julietk@...ux.vnet.ibm.com>
To:     netdev@...r.kernel.org
Cc:     linuxppc-dev@...ts.ozlabs.org, julietk@...ux.vnet.ibm.com,
        tlfalcon@...ux.vnet.ibm.com
Subject: [PATCH] ibmvnic: Do not process device remove during device reset

The ibmvnic driver does not check the device state when the device
is removed. If the device is removed while a device reset is being 
processed, the remove may free structures needed by the reset, 
causing an oops.

Fix this by checking the device state before processing device remove.

Signed-off-by: Juliet Kim <julietk@...ux.vnet.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 24 ++++++++++++++++++++++--
 drivers/net/ethernet/ibm/ibmvnic.h |  6 +++++-
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index c75239d8820f..7ef1ae0d49bc 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -2144,6 +2144,8 @@ static void __ibmvnic_reset(struct work_struct *work)
 	struct ibmvnic_adapter *adapter;
 	u32 reset_state;
 	int rc = 0;
+	unsigned long flags;
+	bool saved_state = false;
 
 	adapter = container_of(work, struct ibmvnic_adapter, ibmvnic_reset);
 
@@ -2153,17 +2155,25 @@ static void __ibmvnic_reset(struct work_struct *work)
 		return;
 	}
 
-	reset_state = adapter->state;
-
 	rwi = get_next_rwi(adapter);
 	while (rwi) {
+		spin_lock_irqsave(&adapter->state_lock, flags);
+
 		if (adapter->state == VNIC_REMOVING ||
 		    adapter->state == VNIC_REMOVED) {
+			spin_unlock_irqrestore(&adapter->state_lock, flags);
 			kfree(rwi);
 			rc = EBUSY;
 			break;
 		}
 
+		if (!saved_state) {
+			reset_state = adapter->state;
+			adapter->state = VNIC_RESETTING;
+			saved_state = true;
+		}
+		spin_unlock_irqrestore(&adapter->state_lock, flags);
+
 		if (rwi->reset_reason == VNIC_RESET_CHANGE_PARAM) {
 			/* CHANGE_PARAM requestor holds rtnl_lock */
 			rc = do_change_param_reset(adapter, rwi, reset_state);
@@ -5091,6 +5101,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 			  __ibmvnic_delayed_reset);
 	INIT_LIST_HEAD(&adapter->rwi_list);
 	spin_lock_init(&adapter->rwi_lock);
+	spin_lock_init(&adapter->state_lock);
 	mutex_init(&adapter->fw_lock);
 	init_completion(&adapter->init_done);
 	init_completion(&adapter->fw_done);
@@ -5161,10 +5172,19 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 
 static int ibmvnic_remove(struct vio_dev *dev)
 {
+	unsigned long flags;
 	struct net_device *netdev = dev_get_drvdata(&dev->dev);
 	struct ibmvnic_adapter *adapter = netdev_priv(netdev);
 
+	spin_lock_irqsave(&adapter->state_lock, flags);
+	if (adapter->state == VNIC_RESETTING) {
+		spin_unlock_irqrestore(&adapter->state_lock, flags);
+		return -EBUSY;
+	}
+
 	adapter->state = VNIC_REMOVING;
+	spin_unlock_irqrestore(&adapter->state_lock, flags);
+
 	rtnl_lock();
 	unregister_netdevice(netdev);
 
diff --git a/drivers/net/ethernet/ibm/ibmvnic.h b/drivers/net/ethernet/ibm/ibmvnic.h
index 60eccaf91b12..971505e4cc52 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.h
+++ b/drivers/net/ethernet/ibm/ibmvnic.h
@@ -941,7 +941,8 @@ enum vnic_state {VNIC_PROBING = 1,
 		 VNIC_CLOSING,
 		 VNIC_CLOSED,
 		 VNIC_REMOVING,
-		 VNIC_REMOVED};
+		 VNIC_REMOVED,
+		 VNIC_RESETTING};
 
 enum ibmvnic_reset_reason {VNIC_RESET_FAILOVER = 1,
 			   VNIC_RESET_MOBILITY,
@@ -1090,4 +1091,7 @@ struct ibmvnic_adapter {
 
 	struct ibmvnic_tunables desired;
 	struct ibmvnic_tunables fallback;
+
+	/* lock to protect state field */
+	spinlock_t state_lock;
 };
-- 
2.25.0

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