net/ibmvnic: unlock rtnl_lock in reset so linkwatch_event can run

Commit a5681e20b541 ("net/ibmnvic: Fix deadlock problem in reset")
made the change to hold the RTNL lock during a reset to avoid deadlock
but linkwatch_event is fired during the reset and needs the RTNL lock.
That keeps linkwatch_event process from proceeding until the reset
is complete. The reset process cannot tolerate the linkwatch_event
processing after reset completes, so release the RTNL lock during the
process to allow a chance for linkwatch_event to run during reset.
This does not guarantee that the linkwatch_event will be processed as
soon as link state changes, but is an improvement over the current code
where linkwatch_event processing is always delayed, which prevents
transmissions on the device from being deactivated leading transmit
watchdog timer to time-out.

Release the RTNL lock before link state change and re-acquire after
the link state change to allow linkwatch_event to grab the RTNL lock
and run during the reset.

Fixes: a5681e20b541 ("net/ibmnvic: Fix deadlock problem in reset")
Signed-off-by: Juliet Kim <julietk@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 3816fff75bb585eae995b172926693d880e09634..d7db5cc51f6ac94a9babcbdd6ba338632b91cb74 100644 (file)
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -1723,6 +1723,86 @@ static int ibmvnic_set_mac(struct net_device *netdev, void *p)
        return rc;
 }
 
+/**
+ * do_change_param_reset returns zero if we are able to keep processing reset
+ * events, or non-zero if we hit a fatal error and must halt.
+ */
+static int do_change_param_reset(struct ibmvnic_adapter *adapter,
+                                struct ibmvnic_rwi *rwi,
+                                u32 reset_state)
+{
+       struct net_device *netdev = adapter->netdev;
+       int i, rc;
+
+       netdev_dbg(adapter->netdev, "Change param resetting driver (%d)\n",
+                  rwi->reset_reason);
+
+       netif_carrier_off(netdev);
+       adapter->reset_reason = rwi->reset_reason;
+
+       ibmvnic_cleanup(netdev);
+
+       if (reset_state == VNIC_OPEN) {
+               rc = __ibmvnic_close(netdev);
+               if (rc)
+                       return rc;
+       }
+
+       release_resources(adapter);
+       release_sub_crqs(adapter, 1);
+       release_crq_queue(adapter);
+
+       adapter->state = VNIC_PROBED;
+
+       rc = init_crq_queue(adapter);
+
+       if (rc) {
+               netdev_err(adapter->netdev,
+                          "Couldn't initialize crq. rc=%d\n", rc);
+               return rc;
+       }
+
+       rc = ibmvnic_reset_init(adapter);
+       if (rc)
+               return IBMVNIC_INIT_FAILED;
+
+       /* If the adapter was in PROBE state prior to the reset,
+        * exit here.
+        */
+       if (reset_state == VNIC_PROBED)
+               return 0;
+
+       rc = ibmvnic_login(netdev);
+       if (rc) {
+               adapter->state = reset_state;
+               return rc;
+       }
+
+       rc = init_resources(adapter);
+       if (rc)
+               return rc;
+
+       ibmvnic_disable_irqs(adapter);
+
+       adapter->state = VNIC_CLOSED;
+
+       if (reset_state == VNIC_CLOSED)
+               return 0;
+
+       rc = __ibmvnic_open(netdev);
+       if (rc)
+               return IBMVNIC_OPEN_FAILED;
+
+       /* refresh device's multicast list */
+       ibmvnic_set_multi(netdev);
+
+       /* kick napi */
+       for (i = 0; i < adapter->req_rx_queues; i++)
+               napi_schedule(&adapter->napi[i]);
+
+       return 0;
+}
+
 /**
  * do_reset returns zero if we are able to keep processing reset events, or
  * non-zero if we hit a fatal error and must halt.
@@ -1738,6 +1818,8 @@ static int do_reset(struct ibmvnic_adapter *adapter,
        netdev_dbg(adapter->netdev, "Re-setting driver (%d)\n",
                   rwi->reset_reason);
 
+       rtnl_lock();
+
        netif_carrier_off(netdev);
        adapter->reset_reason = rwi->reset_reason;
 
@@ -1751,16 +1833,25 @@ static int do_reset(struct ibmvnic_adapter *adapter,
        if (reset_state == VNIC_OPEN &&
            adapter->reset_reason != VNIC_RESET_MOBILITY &&
            adapter->reset_reason != VNIC_RESET_FAILOVER) {
-               rc = __ibmvnic_close(netdev);
+               adapter->state = VNIC_CLOSING;
+
+               /* Release the RTNL lock before link state change and
+                * re-acquire after the link state change to allow
+                * linkwatch_event to grab the RTNL lock and run during
+                * a reset.
+                */
+               rtnl_unlock();
+               rc = set_link_state(adapter, IBMVNIC_LOGICAL_LNK_DN);
+               rtnl_lock();
                if (rc)
-                       return rc;
-       }
+                       goto out;
 
-       if (adapter->reset_reason == VNIC_RESET_CHANGE_PARAM ||
-           adapter->wait_for_reset) {
-               release_resources(adapter);
-               release_sub_crqs(adapter, 1);
-               release_crq_queue(adapter);
+               if (adapter->state != VNIC_CLOSING) {
+                       rc = -1;
+                       goto out;
+               }
+
+               adapter->state = VNIC_CLOSED;
        }
 
        if (adapter->reset_reason != VNIC_RESET_NON_FATAL) {
@@ -1769,9 +1860,7 @@ static int do_reset(struct ibmvnic_adapter *adapter,
                 */
                adapter->state = VNIC_PROBED;
 
-               if (adapter->wait_for_reset) {
-                       rc = init_crq_queue(adapter);
-               } else if (adapter->reset_reason == VNIC_RESET_MOBILITY) {
+               if (adapter->reset_reason == VNIC_RESET_MOBILITY) {
                        rc = ibmvnic_reenable_crq_queue(adapter);
                        release_sub_crqs(adapter, 1);
                } else {
@@ -1783,36 +1872,35 @@ static int do_reset(struct ibmvnic_adapter *adapter,
                if (rc) {
                        netdev_err(adapter->netdev,
                                   "Couldn't initialize crq. rc=%d\n", rc);
-                       return rc;
+                       goto out;
                }
 
                rc = ibmvnic_reset_init(adapter);
-               if (rc)
-                       return IBMVNIC_INIT_FAILED;
+               if (rc) {
+                       rc = IBMVNIC_INIT_FAILED;
+                       goto out;
+               }
 
                /* If the adapter was in PROBE state prior to the reset,
                 * exit here.
                 */
-               if (reset_state == VNIC_PROBED)
-                       return 0;
+               if (reset_state == VNIC_PROBED) {
+                       rc = 0;
+                       goto out;
+               }
 
                rc = ibmvnic_login(netdev);
                if (rc) {
                        adapter->state = reset_state;
-                       return rc;
+                       goto out;
                }
 
-               if (adapter->reset_reason == VNIC_RESET_CHANGE_PARAM ||
-                   adapter->wait_for_reset) {
-                       rc = init_resources(adapter);
-                       if (rc)
-                               return rc;
-               } else if (adapter->req_rx_queues != old_num_rx_queues ||
-                          adapter->req_tx_queues != old_num_tx_queues ||
-                          adapter->req_rx_add_entries_per_subcrq !=
-                                                       old_num_rx_slots ||
-                          adapter->req_tx_entries_per_subcrq !=
-                                                       old_num_tx_slots) {
+               if (adapter->req_rx_queues != old_num_rx_queues ||
+                   adapter->req_tx_queues != old_num_tx_queues ||
+                   adapter->req_rx_add_entries_per_subcrq !=
+                   old_num_rx_slots ||
+                   adapter->req_tx_entries_per_subcrq !=
+                   old_num_tx_slots) {
                        release_rx_pools(adapter);
                        release_tx_pools(adapter);
                        release_napi(adapter);
@@ -1820,32 +1908,30 @@ static int do_reset(struct ibmvnic_adapter *adapter,
 
                        rc = init_resources(adapter);
                        if (rc)
-                               return rc;
+                               goto out;
 
                } else {
                        rc = reset_tx_pools(adapter);
                        if (rc)
-                               return rc;
+                               goto out;
 
                        rc = reset_rx_pools(adapter);
                        if (rc)
-                               return rc;
+                               goto out;
                }
                ibmvnic_disable_irqs(adapter);
        }
        adapter->state = VNIC_CLOSED;
 
-       if (reset_state == VNIC_CLOSED)
-               return 0;
+       if (reset_state == VNIC_CLOSED) {
+               rc = 0;
+               goto out;
+       }
 
        rc = __ibmvnic_open(netdev);
        if (rc) {
-               if (list_empty(&adapter->rwi_list))
-                       adapter->state = VNIC_CLOSED;
-               else
-                       adapter->state = reset_state;
-
-               return 0;
+               rc = IBMVNIC_OPEN_FAILED;
+               goto out;
        }
 
        /* refresh device's multicast list */
@@ -1855,11 +1941,15 @@ static int do_reset(struct ibmvnic_adapter *adapter,
        for (i = 0; i < adapter->req_rx_queues; i++)
                napi_schedule(&adapter->napi[i]);
 
-       if (adapter->reset_reason != VNIC_RESET_FAILOVER &&
-           adapter->reset_reason != VNIC_RESET_CHANGE_PARAM)
+       if (adapter->reset_reason != VNIC_RESET_FAILOVER)
                call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, netdev);
 
-       return 0;
+       rc = 0;
+
+out:
+       rtnl_unlock();
+
+       return rc;
 }
 
 static int do_hard_reset(struct ibmvnic_adapter *adapter,
@@ -1919,14 +2009,8 @@ static int do_hard_reset(struct ibmvnic_adapter *adapter,
                return 0;
 
        rc = __ibmvnic_open(netdev);
-       if (rc) {
-               if (list_empty(&adapter->rwi_list))
-                       adapter->state = VNIC_CLOSED;
-               else
-                       adapter->state = reset_state;
-
-               return 0;
-       }
+       if (rc)
+               return IBMVNIC_OPEN_FAILED;
 
        return 0;
 }
@@ -1965,20 +2049,11 @@ static void __ibmvnic_reset(struct work_struct *work)
 {
        struct ibmvnic_rwi *rwi;
        struct ibmvnic_adapter *adapter;
-       bool we_lock_rtnl = false;
        u32 reset_state;
        int rc = 0;
 
        adapter = container_of(work, struct ibmvnic_adapter, ibmvnic_reset);
 
-       /* 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);
@@ -1990,14 +2065,32 @@ static void __ibmvnic_reset(struct work_struct *work)
                        break;
                }
 
-               if (adapter->force_reset_recovery) {
-                       adapter->force_reset_recovery = false;
-                       rc = do_hard_reset(adapter, rwi, reset_state);
+               if (rwi->reset_reason == VNIC_RESET_CHANGE_PARAM) {
+                       /* CHANGE_PARAM requestor holds rtnl_lock */
+                       rc = do_change_param_reset(adapter, rwi, reset_state);
+               } else if (adapter->force_reset_recovery) {
+                       /* Transport event occurred during previous reset */
+                       if (adapter->wait_for_reset) {
+                               /* Previous was CHANGE_PARAM; caller locked */
+                               adapter->force_reset_recovery = false;
+                               rc = do_hard_reset(adapter, rwi, reset_state);
+                       } else {
+                               rtnl_lock();
+                               adapter->force_reset_recovery = false;
+                               rc = do_hard_reset(adapter, rwi, reset_state);
+                               rtnl_unlock();
+                       }
                } else {
                        rc = do_reset(adapter, rwi, reset_state);
                }
                kfree(rwi);
-               if (rc && rc != IBMVNIC_INIT_FAILED &&
+               if (rc == IBMVNIC_OPEN_FAILED) {
+                       if (list_empty(&adapter->rwi_list))
+                               adapter->state = VNIC_CLOSED;
+                       else
+                               adapter->state = reset_state;
+                       rc = 0;
+               } else if (rc && rc != IBMVNIC_INIT_FAILED &&
                    !adapter->force_reset_recovery)
                        break;
 
@@ -2005,7 +2098,6 @@ static void __ibmvnic_reset(struct work_struct *work)
        }
 
        if (adapter->wait_for_reset) {
-               adapter->wait_for_reset = false;
                adapter->reset_done_rc = rc;
                complete(&adapter->reset_done);
        }
@@ -2016,8 +2108,6 @@ static void __ibmvnic_reset(struct work_struct *work)
        }
 
        adapter->resetting = false;
-       if (we_lock_rtnl)
-               rtnl_unlock();
 }
 
 static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
@@ -2078,8 +2168,6 @@ static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
 
        return 0;
 err:
-       if (adapter->wait_for_reset)
-               adapter->wait_for_reset = false;
        return -ret;
 }
 

diff --git a/drivers/net/ethernet/ibm/ibmvnic.h b/drivers/net/ethernet/ibm/ibmvnic.h
index 70bd286f89325d34cad7831ce793860f5a4eed8f..9d3d35cc91d6f76490b6f572d8e727a699f0068a 100644 (file)
--- a/drivers/net/ethernet/ibm/ibmvnic.h
+++ b/drivers/net/ethernet/ibm/ibmvnic.h
@@ -20,6 +20,7 @@
 #define IBMVNIC_INVALID_MAP    -1
 #define IBMVNIC_STATS_TIMEOUT  1
 #define IBMVNIC_INIT_FAILED    2
+#define IBMVNIC_OPEN_FAILED    3
 
 /* basic structures plus 100 2k buffers */
 #define IBMVNIC_IO_ENTITLEMENT_DEFAULT 610305