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Subject[PATCH] net/ibmnvic: Fix deadlock problem in reset
Date
Subject: [PATCH] net/ibmnvic: Fix deadlock problem in reset

From: Juliet Kim <julietk@linux.vnet.ibm.com>

This patch changes to use rtnl_lock only during a reset to avoid
deadlock that could occur when a thread operating close is holding
rtnl_lock and waiting for reset_lock acquired by another thread,
which is waiting for rtnl_lock in order to set the number of tx/rx
queues during a reset.

Also, we now setting the number of tx/rx queues during a soft reset
for failover or LPM events.

Signed-off-by: Juliet Kim <julietk@linux.vnet.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c |   59
+++++++++++++-----------------------
 drivers/net/ethernet/ibm/ibmvnic.h |    2 +
 2 files changed, 22 insertions(+), 39 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c
b/drivers/net/ethernet/ibm/ibmvnic.c
index 7893bef..4a5de59 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -1103,20 +1103,15 @@ static int ibmvnic_open(struct net_device *netdev)
        return 0;
    }

-   mutex_lock(&adapter->reset_lock);
-
    if (adapter->state != VNIC_CLOSED) {
        rc = ibmvnic_login(netdev);
-       if (rc) {
-           mutex_unlock(&adapter->reset_lock);
+       if (rc)
            return rc;
-       }

        rc = init_resources(adapter);
        if (rc) {
            netdev_err(netdev, "failed to initialize resources\n");
            release_resources(adapter);
-           mutex_unlock(&adapter->reset_lock);
            return rc;
        }
    }
@@ -1124,8 +1119,6 @@ static int ibmvnic_open(struct net_device *netdev)
    rc = __ibmvnic_open(netdev);
    netif_carrier_on(netdev);

-   mutex_unlock(&adapter->reset_lock);
-
    return rc;
 }

@@ -1269,10 +1262,8 @@ static int ibmvnic_close(struct net_device *netdev)
        return 0;
    }

-   mutex_lock(&adapter->reset_lock);
    rc = __ibmvnic_close(netdev);
    ibmvnic_cleanup(netdev);
-   mutex_unlock(&adapter->reset_lock);

    return rc;
 }
@@ -1820,20 +1811,15 @@ static int do_reset(struct ibmvnic_adapter *adapter,
                return rc;
        } else if (adapter->req_rx_queues != old_num_rx_queues ||
               adapter->req_tx_queues != old_num_tx_queues) {
-           adapter->map_id = 1;
            release_rx_pools(adapter);
            release_tx_pools(adapter);
-           rc = init_rx_pools(netdev);
-           if (rc)
-               return rc;
-           rc = init_tx_pools(netdev);
-           if (rc)
-               return rc;
-
            release_napi(adapter);
-           rc = init_napi(adapter);
+           release_vpd_data(adapter);
+
+           rc = init_resources(adapter);
            if (rc)
                return rc;
+
        } else {
            rc = reset_tx_pools(adapter);
            if (rc)
@@ -1917,17 +1903,8 @@ static int do_hard_reset(struct ibmvnic_adapter
*adapter,
        adapter->state = VNIC_PROBED;
        return 0;
    }
-   /* netif_set_real_num_xx_queues needs to take rtnl lock here
-    * unless wait_for_reset is set, in which case the rtnl lock
-    * has already been taken before initializing the reset
-    */
-   if (!adapter->wait_for_reset) {
-       rtnl_lock();
-       rc = init_resources(adapter);
-       rtnl_unlock();
-   } else {
-       rc = init_resources(adapter);
-   }
+
+   rc = init_resources(adapter);
    if (rc)
        return rc;

@@ -1986,13 +1963,21 @@ static void __ibmvnic_reset(struct work_struct
*work)
    struct ibmvnic_rwi *rwi;
    struct ibmvnic_adapter *adapter;
    struct net_device *netdev;
+   bool we_lock_rtnl = false;
    u32 reset_state;
    int rc = 0;

    adapter = container_of(work, struct ibmvnic_adapter, ibmvnic_reset);
    netdev = adapter->netdev;

-   mutex_lock(&adapter->reset_lock);
+   /* netif_set_real_num_xx_queues needs to take rtnl lock here
+    * unless wait_for_reset is set, in which case the rtnl lock
+    * has already been taken before initializing the reset
+    */
+   if (!adapter->wait_for_reset) {
+       rtnl_lock();
+       we_lock_rtnl = true;
+   }

    reset_state = adapter->state;

    rwi = get_next_rwi(adapter);
@@ -2020,12 +2005,11 @@ static void __ibmvnic_reset(struct work_struct
*work)
    if (rc) {
        netdev_dbg(adapter->netdev, "Reset failed\n");
        free_all_rwi(adapter);
-       mutex_unlock(&adapter->reset_lock);
-       return;
    }
    adapter->resetting = false;
-   mutex_unlock(&adapter->reset_lock);
+   if (we_lock_rtnl)
+       rtnl_unlock();
 }
 static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
@@ -4768,7 +4752,6 @@ static int ibmvnic_probe(struct vio_dev *dev,
const struct vio_device_id *id)

    INIT_WORK(&adapter->ibmvnic_reset, __ibmvnic_reset);
    INIT_LIST_HEAD(&adapter->rwi_list);
-   mutex_init(&adapter->reset_lock);
    mutex_init(&adapter->rwi_lock);
    adapter->resetting = false;

@@ -4840,8 +4823,8 @@ static int ibmvnic_remove(struct vio_dev *dev)
    struct ibmvnic_adapter *adapter = netdev_priv(netdev);

    adapter->state = VNIC_REMOVING;
-   unregister_netdev(netdev);
-   mutex_lock(&adapter->reset_lock);
+   rtnl_lock();
+   unregister_netdevice(netdev);

    release_resources(adapter);
    release_sub_crqs(adapter, 1);
@@ -4852,7 +4835,7 @@ static int ibmvnic_remove(struct vio_dev *dev)

    adapter->state = VNIC_REMOVED;

-   mutex_unlock(&adapter->reset_lock);
+   rtnl_unlock();
    device_remove_file(&dev->dev, &dev_attr_failover);
    free_netdev(netdev);
    dev_set_drvdata(&dev->dev, NULL);
diff --git a/drivers/net/ethernet/ibm/ibmvnic.h
b/drivers/net/ethernet/ibm/ibmvnic.h
index 18103b8..99c4f8d 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.h
+++ b/drivers/net/ethernet/ibm/ibmvnic.h
@@ -1075,7 +1075,7 @@ struct ibmvnic_adapter {
    struct tasklet_struct tasklet;
    enum vnic_state state;
    enum ibmvnic_reset_reason reset_reason;
-   struct mutex reset_lock, rwi_lock;
+   struct mutex rwi_lock;
    struct list_head rwi_list;
    struct work_struct ibmvnic_reset;
    bool resetting;
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