Merge branch 'ibmvnic-fixes'

Sukadev Bhattiprolu says:

====================
ibmvnic: Fix a race in ibmvnic_probe()

If we get a transport (reset) event right after a successful CRQ_INIT
during ibmvnic_probe() but before we set the adapter state to VNIC_PROBED,
we will throw away the reset assuming that the adapter is still in the
probing state. But since the adapter has completed the CRQ_INIT any
subsequent CRQs the we send will be ignored by the vnicserver until
we release/init the CRQ again. This can leave the adapter unconfigured.

While here fix a couple of other bugs that were observed (Patches 1,2,4).
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 156 insertions, 28 deletions

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index dee05a353dbd..b423e94956f1 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -2213,6 +2213,19 @@ static const char *reset_reason_to_string(enum ibmvnic_reset_reason reason)
 }
 
 /*
+ * Initialize the init_done completion and return code values. We
+ * can get a transport event just after registering the CRQ and the
+ * tasklet will use this to communicate the transport event. To ensure
+ * we don't miss the notification/error, initialize these _before_
+ * regisering the CRQ.
+ */
+static inline void reinit_init_done(struct ibmvnic_adapter *adapter)
+{
+	reinit_completion(&adapter->init_done);
+	adapter->init_done_rc = 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.
  */
@@ -2318,6 +2331,8 @@ static int do_reset(struct ibmvnic_adapter *adapter,
 		 */
 		adapter->state = VNIC_PROBED;
 
+		reinit_init_done(adapter);
+
 		if (adapter->reset_reason == VNIC_RESET_CHANGE_PARAM) {
 			rc = init_crq_queue(adapter);
 		} else if (adapter->reset_reason == VNIC_RESET_MOBILITY) {
@@ -2461,7 +2476,8 @@ static int do_hard_reset(struct ibmvnic_adapter *adapter,
 	 */
 	adapter->state = VNIC_PROBED;
 
-	reinit_completion(&adapter->init_done);
+	reinit_init_done(adapter);
+
 	rc = init_crq_queue(adapter);
 	if (rc) {
 		netdev_err(adapter->netdev,
@@ -2602,23 +2618,82 @@ out:
 static void __ibmvnic_reset(struct work_struct *work)
 {
 	struct ibmvnic_adapter *adapter;
-	bool saved_state = false;
+	unsigned int timeout = 5000;
 	struct ibmvnic_rwi *tmprwi;
+	bool saved_state = false;
 	struct ibmvnic_rwi *rwi;
 	unsigned long flags;
-	u32 reset_state;
+	struct device *dev;
+	bool need_reset;
 	int num_fails = 0;
+	u32 reset_state;
 	int rc = 0;
 
 	adapter = container_of(work, struct ibmvnic_adapter, ibmvnic_reset);
+		dev = &adapter->vdev->dev;
 
-	if (test_and_set_bit_lock(0, &adapter->resetting)) {
+	/* Wait for ibmvnic_probe() to complete. If probe is taking too long
+	 * or if another reset is in progress, defer work for now. If probe
+	 * eventually fails it will flush and terminate our work.
+	 *
+	 * Three possibilities here:
+	 * 1. Adpater being removed  - just return
+	 * 2. Timed out on probe or another reset in progress - delay the work
+	 * 3. Completed probe - perform any resets in queue
+	 */
+	if (adapter->state == VNIC_PROBING &&
+	    !wait_for_completion_timeout(&adapter->probe_done, timeout)) {
+		dev_err(dev, "Reset thread timed out on probe");
 		queue_delayed_work(system_long_wq,
 				   &adapter->ibmvnic_delayed_reset,
 				   IBMVNIC_RESET_DELAY);
 		return;
 	}
 
+	/* adapter is done with probe (i.e state is never VNIC_PROBING now) */
+	if (adapter->state == VNIC_REMOVING)
+		return;
+
+	/* ->rwi_list is stable now (no one else is removing entries) */
+
+	/* ibmvnic_probe() may have purged the reset queue after we were
+	 * scheduled to process a reset so there maybe no resets to process.
+	 * Before setting the ->resetting bit though, we have to make sure
+	 * that there is infact a reset to process. Otherwise we may race
+	 * with ibmvnic_open() and end up leaving the vnic down:
+	 *
+	 *	__ibmvnic_reset()	    ibmvnic_open()
+	 *	-----------------	    --------------
+	 *
+	 *  set ->resetting bit
+	 *  				find ->resetting bit is set
+	 *  				set ->state to IBMVNIC_OPEN (i.e
+	 *  				assume reset will open device)
+	 *  				return
+	 *  find reset queue empty
+	 *  return
+	 *
+	 *  	Neither performed vnic login/open and vnic stays down
+	 *
+	 * If we hold the lock and conditionally set the bit, either we
+	 * or ibmvnic_open() will complete the open.
+	 */
+	need_reset = false;
+	spin_lock(&adapter->rwi_lock);
+	if (!list_empty(&adapter->rwi_list)) {
+		if (test_and_set_bit_lock(0, &adapter->resetting)) {
+			queue_delayed_work(system_long_wq,
+					   &adapter->ibmvnic_delayed_reset,
+					   IBMVNIC_RESET_DELAY);
+		} else {
+			need_reset = true;
+		}
+	}
+	spin_unlock(&adapter->rwi_lock);
+
+	if (!need_reset)
+		return;
+
 	rwi = get_next_rwi(adapter);
 	while (rwi) {
 		spin_lock_irqsave(&adapter->state_lock, flags);
@@ -2735,12 +2810,23 @@ static void __ibmvnic_delayed_reset(struct work_struct *work)
 	__ibmvnic_reset(&adapter->ibmvnic_reset);
 }
 
+static void flush_reset_queue(struct ibmvnic_adapter *adapter)
+{
+	struct list_head *entry, *tmp_entry;
+
+	if (!list_empty(&adapter->rwi_list)) {
+		list_for_each_safe(entry, tmp_entry, &adapter->rwi_list) {
+			list_del(entry);
+			kfree(list_entry(entry, struct ibmvnic_rwi, list));
+		}
+	}
+}
+
 static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
 			 enum ibmvnic_reset_reason reason)
 {
-	struct list_head *entry, *tmp_entry;
-	struct ibmvnic_rwi *rwi, *tmp;
 	struct net_device *netdev = adapter->netdev;
+	struct ibmvnic_rwi *rwi, *tmp;
 	unsigned long flags;
 	int ret;
 
@@ -2759,13 +2845,6 @@ static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
 		goto err;
 	}
 
-	if (adapter->state == VNIC_PROBING) {
-		netdev_warn(netdev, "Adapter reset during probe\n");
-		adapter->init_done_rc = -EAGAIN;
-		ret = EAGAIN;
-		goto err;
-	}
-
 	list_for_each_entry(tmp, &adapter->rwi_list, list) {
 		if (tmp->reset_reason == reason) {
 			netdev_dbg(netdev, "Skipping matching reset, reason=%s\n",
@@ -2783,10 +2862,9 @@ static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
 	/* if we just received a transport event,
 	 * flush reset queue and process this reset
 	 */
-	if (adapter->force_reset_recovery && !list_empty(&adapter->rwi_list)) {
-		list_for_each_safe(entry, tmp_entry, &adapter->rwi_list)
-			list_del(entry);
-	}
+	if (adapter->force_reset_recovery)
+		flush_reset_queue(adapter);
+
 	rwi->reset_reason = reason;
 	list_add_tail(&rwi->list, &adapter->rwi_list);
 	netdev_dbg(adapter->netdev, "Scheduling reset (reason %s)\n",
@@ -5321,9 +5399,9 @@ static void ibmvnic_handle_crq(union ibmvnic_crq *crq,
 			}
 
 			if (!completion_done(&adapter->init_done)) {
-				complete(&adapter->init_done);
 				if (!adapter->init_done_rc)
 					adapter->init_done_rc = -EAGAIN;
+				complete(&adapter->init_done);
 			}
 
 			break;
@@ -5346,6 +5424,13 @@ static void ibmvnic_handle_crq(union ibmvnic_crq *crq,
 			adapter->fw_done_rc = -EIO;
 			complete(&adapter->fw_done);
 		}
+
+		/* if we got here during crq-init, retry crq-init */
+		if (!completion_done(&adapter->init_done)) {
+			adapter->init_done_rc = -EAGAIN;
+			complete(&adapter->init_done);
+		}
+
 		if (!completion_done(&adapter->stats_done))
 			complete(&adapter->stats_done);
 		if (test_bit(0, &adapter->resetting))
@@ -5662,10 +5747,6 @@ static int ibmvnic_reset_init(struct ibmvnic_adapter *adapter, bool reset)
 
 	adapter->from_passive_init = false;
 
-	if (reset)
-		reinit_completion(&adapter->init_done);
-
-	adapter->init_done_rc = 0;
 	rc = ibmvnic_send_crq_init(adapter);
 	if (rc) {
 		dev_err(dev, "Send crq init failed with error %d\n", rc);
@@ -5679,12 +5760,14 @@ static int ibmvnic_reset_init(struct ibmvnic_adapter *adapter, bool reset)
 
 	if (adapter->init_done_rc) {
 		release_crq_queue(adapter);
+		dev_err(dev, "CRQ-init failed, %d\n", adapter->init_done_rc);
 		return adapter->init_done_rc;
 	}
 
 	if (adapter->from_passive_init) {
 		adapter->state = VNIC_OPEN;
 		adapter->from_passive_init = false;
+		dev_err(dev, "CRQ-init failed, passive-init\n");
 		return -EINVAL;
 	}
 
@@ -5724,6 +5807,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 	struct ibmvnic_adapter *adapter;
 	struct net_device *netdev;
 	unsigned char *mac_addr_p;
+	unsigned long flags;
 	bool init_success;
 	int rc;
 
@@ -5768,6 +5852,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 	spin_lock_init(&adapter->rwi_lock);
 	spin_lock_init(&adapter->state_lock);
 	mutex_init(&adapter->fw_lock);
+	init_completion(&adapter->probe_done);
 	init_completion(&adapter->init_done);
 	init_completion(&adapter->fw_done);
 	init_completion(&adapter->reset_done);
@@ -5778,6 +5863,33 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 
 	init_success = false;
 	do {
+		reinit_init_done(adapter);
+
+		/* clear any failovers we got in the previous pass
+		 * since we are reinitializing the CRQ
+		 */
+		adapter->failover_pending = false;
+
+		/* If we had already initialized CRQ, we may have one or
+		 * more resets queued already. Discard those and release
+		 * the CRQ before initializing the CRQ again.
+		 */
+		release_crq_queue(adapter);
+
+		/* Since we are still in PROBING state, __ibmvnic_reset()
+		 * will not access the ->rwi_list and since we released CRQ,
+		 * we won't get _new_ transport events. But there maybe an
+		 * ongoing ibmvnic_reset() call. So serialize access to
+		 * rwi_list. If we win the race, ibvmnic_reset() could add
+		 * a reset after we purged but thats ok - we just may end
+		 * up with an extra reset (i.e similar to having two or more
+		 * resets in the queue at once).
+		 * CHECK.
+		 */
+		spin_lock_irqsave(&adapter->rwi_lock, flags);
+		flush_reset_queue(adapter);
+		spin_unlock_irqrestore(&adapter->rwi_lock, flags);
+
 		rc = init_crq_queue(adapter);
 		if (rc) {
 			dev_err(&dev->dev, "Couldn't initialize crq. rc=%d\n",
@@ -5809,12 +5921,6 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 		goto ibmvnic_dev_file_err;
 
 	netif_carrier_off(netdev);
-	rc = register_netdev(netdev);
-	if (rc) {
-		dev_err(&dev->dev, "failed to register netdev rc=%d\n", rc);
-		goto ibmvnic_register_fail;
-	}
-	dev_info(&dev->dev, "ibmvnic registered\n");
 
 	if (init_success) {
 		adapter->state = VNIC_PROBED;
@@ -5827,6 +5933,16 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 
 	adapter->wait_for_reset = false;
 	adapter->last_reset_time = jiffies;
+
+	rc = register_netdev(netdev);
+	if (rc) {
+		dev_err(&dev->dev, "failed to register netdev rc=%d\n", rc);
+		goto ibmvnic_register_fail;
+	}
+	dev_info(&dev->dev, "ibmvnic registered\n");
+
+	complete(&adapter->probe_done);
+
 	return 0;
 
 ibmvnic_register_fail:
@@ -5841,6 +5957,17 @@ ibmvnic_stats_fail:
 ibmvnic_init_fail:
 	release_sub_crqs(adapter, 1);
 	release_crq_queue(adapter);
+
+	/* cleanup worker thread after releasing CRQ so we don't get
+	 * transport events (i.e new work items for the worker thread).
+	 */
+	adapter->state = VNIC_REMOVING;
+	complete(&adapter->probe_done);
+	flush_work(&adapter->ibmvnic_reset);
+	flush_delayed_work(&adapter->ibmvnic_delayed_reset);
+
+	flush_reset_queue(adapter);
+
 	mutex_destroy(&adapter->fw_lock);
 	free_netdev(netdev);
 
diff --git a/drivers/net/ethernet/ibm/ibmvnic.h b/drivers/net/ethernet/ibm/ibmvnic.h
index 4a7a56ff74ce..fa2d607a7b1b 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.h
+++ b/drivers/net/ethernet/ibm/ibmvnic.h
@@ -930,6 +930,7 @@ struct ibmvnic_adapter {
 
 	struct ibmvnic_tx_pool *tx_pool;
 	struct ibmvnic_tx_pool *tso_pool;
+	struct completion probe_done;
 	struct completion init_done;
 	int init_done_rc;