[PATCH net] iavf: fix deadlock in reset handling

[Petr Oros <poros@redhat.com>]

description... 

Fixes: 120f28a6f314 ("iavf: get rid of the crit lock")
Signed-off-by: Petr Oros <poros@redhat.com>
---
 drivers/net/ethernet/intel/iavf/iavf.h        |  2 +-
 .../net/ethernet/intel/iavf/iavf_ethtool.c    | 21 +++---
 drivers/net/ethernet/intel/iavf/iavf_main.c   | 72 +++++++------------
 3 files changed, 33 insertions(+), 62 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf.h b/drivers/net/ethernet/intel/iavf/iavf.h
index d552f912e8a947..0c3844b3ff1c86 100644
--- a/drivers/net/ethernet/intel/iavf/iavf.h
+++ b/drivers/net/ethernet/intel/iavf/iavf.h
@@ -625,5 +625,5 @@ void iavf_add_adv_rss_cfg(struct iavf_adapter *adapter);
 void iavf_del_adv_rss_cfg(struct iavf_adapter *adapter);
 struct iavf_mac_filter *iavf_add_filter(struct iavf_adapter *adapter,
 					const u8 *macaddr);
-int iavf_wait_for_reset(struct iavf_adapter *adapter);
+void iavf_reset_step(struct iavf_adapter *adapter);
 #endif /* _IAVF_H_ */
diff --git a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
index 2cc21289a70779..9b0f47f9340942 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
@@ -492,7 +492,6 @@ static int iavf_set_ringparam(struct net_device *netdev,
 {
 	struct iavf_adapter *adapter = netdev_priv(netdev);
 	u32 new_rx_count, new_tx_count;
-	int ret = 0;
 
 	if ((ring->rx_mini_pending) || (ring->rx_jumbo_pending))
 		return -EINVAL;
@@ -537,13 +536,11 @@ static int iavf_set_ringparam(struct net_device *netdev,
 	}
 
 	if (netif_running(netdev)) {
-		iavf_schedule_reset(adapter, IAVF_FLAG_RESET_NEEDED);
-		ret = iavf_wait_for_reset(adapter);
-		if (ret)
-			netdev_warn(netdev, "Changing ring parameters timeout or interrupted waiting for reset");
+		adapter->flags |= IAVF_FLAG_RESET_NEEDED;
+		iavf_reset_step(adapter);
 	}
 
-	return ret;
+	return 0;
 }
 
 /**
@@ -1723,7 +1720,6 @@ static int iavf_set_channels(struct net_device *netdev,
 {
 	struct iavf_adapter *adapter = netdev_priv(netdev);
 	u32 num_req = ch->combined_count;
-	int ret = 0;
 
 	if ((adapter->vf_res->vf_cap_flags & VIRTCHNL_VF_OFFLOAD_ADQ) &&
 	    adapter->num_tc) {
@@ -1745,13 +1741,12 @@ static int iavf_set_channels(struct net_device *netdev,
 
 	adapter->num_req_queues = num_req;
 	adapter->flags |= IAVF_FLAG_REINIT_ITR_NEEDED;
-	iavf_schedule_reset(adapter, IAVF_FLAG_RESET_NEEDED);
-
-	ret = iavf_wait_for_reset(adapter);
-	if (ret)
-		netdev_warn(netdev, "Changing channel count timeout or interrupted waiting for reset");
+	if (netif_running(netdev)) {
+		adapter->flags |= IAVF_FLAG_RESET_NEEDED;
+		iavf_reset_step(adapter);
+	}
 
-	return ret;
+	return 0;
 }
 
 /**
diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
index 8aa6e92c16431f..9c8d6125106f5a 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_main.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
@@ -185,31 +185,6 @@ static bool iavf_is_reset_in_progress(struct iavf_adapter *adapter)
 	return false;
 }
 
-/**
- * iavf_wait_for_reset - Wait for reset to finish.
- * @adapter: board private structure
- *
- * Returns 0 if reset finished successfully, negative on timeout or interrupt.
- */
-int iavf_wait_for_reset(struct iavf_adapter *adapter)
-{
-	int ret = wait_event_interruptible_timeout(adapter->reset_waitqueue,
-					!iavf_is_reset_in_progress(adapter),
-					msecs_to_jiffies(5000));
-
-	/* If ret < 0 then it means wait was interrupted.
-	 * If ret == 0 then it means we got a timeout while waiting
-	 * for reset to finish.
-	 * If ret > 0 it means reset has finished.
-	 */
-	if (ret > 0)
-		return 0;
-	else if (ret < 0)
-		return -EINTR;
-	else
-		return -EBUSY;
-}
-
 /**
  * iavf_allocate_dma_mem_d - OS specific memory alloc for shared code
  * @hw:   pointer to the HW structure
@@ -3100,18 +3075,16 @@ static void iavf_reconfig_qs_bw(struct iavf_adapter *adapter)
 }
 
 /**
- * iavf_reset_task - Call-back task to handle hardware reset
- * @work: pointer to work_struct
+ * iavf_reset_step - Perform the VF reset sequence
+ * @adapter: board private structure
  *
- * During reset we need to shut down and reinitialize the admin queue
- * before we can use it to communicate with the PF again. We also clear
- * and reinit the rings because that context is lost as well.
- **/
-static void iavf_reset_task(struct work_struct *work)
+ * Requests a reset from PF, polls for completion, and reconfigures
+ * the driver. Caller must hold the netdev instance lock.
+ *
+ * This can sleep for several seconds while polling HW registers.
+ */
+void iavf_reset_step(struct iavf_adapter *adapter)
 {
-	struct iavf_adapter *adapter = container_of(work,
-						      struct iavf_adapter,
-						      reset_task);
 	struct virtchnl_vf_resource *vfres = adapter->vf_res;
 	struct net_device *netdev = adapter->netdev;
 	struct iavf_hw *hw = &adapter->hw;
@@ -3122,7 +3095,7 @@ static void iavf_reset_task(struct work_struct *work)
 	int i = 0, err;
 	bool running;
 
-	netdev_lock(netdev);
+	netdev_assert_locked(netdev);
 
 	iavf_misc_irq_disable(adapter);
 	if (adapter->flags & IAVF_FLAG_RESET_NEEDED) {
@@ -3167,7 +3140,6 @@ static void iavf_reset_task(struct work_struct *work)
 		dev_err(&adapter->pdev->dev, "Reset never finished (%x)\n",
 			reg_val);
 		iavf_disable_vf(adapter);
-		netdev_unlock(netdev);
 		return; /* Do not attempt to reinit. It's dead, Jim. */
 	}
 
@@ -3179,7 +3151,6 @@ static void iavf_reset_task(struct work_struct *work)
 		iavf_startup(adapter);
 		queue_delayed_work(adapter->wq, &adapter->watchdog_task,
 				   msecs_to_jiffies(30));
-		netdev_unlock(netdev);
 		return;
 	}
 
@@ -3321,7 +3292,6 @@ static void iavf_reset_task(struct work_struct *work)
 	adapter->flags &= ~IAVF_FLAG_REINIT_ITR_NEEDED;
 
 	wake_up(&adapter->reset_waitqueue);
-	netdev_unlock(netdev);
 
 	return;
 reset_err:
@@ -3331,10 +3301,21 @@ static void iavf_reset_task(struct work_struct *work)
 	}
 	iavf_disable_vf(adapter);
 
-	netdev_unlock(netdev);
 	dev_err(&adapter->pdev->dev, "failed to allocate resources during reinit\n");
 }
 
+static void iavf_reset_task(struct work_struct *work)
+{
+	struct iavf_adapter *adapter = container_of(work,
+						      struct iavf_adapter,
+						      reset_task);
+	struct net_device *netdev = adapter->netdev;
+
+	netdev_lock(netdev);
+	iavf_reset_step(adapter);
+	netdev_unlock(netdev);
+}
+
 /**
  * iavf_adminq_task - worker thread to clean the admin queue
  * @work: pointer to work_struct containing our data
@@ -4600,22 +4581,17 @@ static int iavf_close(struct net_device *netdev)
 static int iavf_change_mtu(struct net_device *netdev, int new_mtu)
 {
 	struct iavf_adapter *adapter = netdev_priv(netdev);
-	int ret = 0;
 
 	netdev_dbg(netdev, "changing MTU from %d to %d\n",
 		   netdev->mtu, new_mtu);
 	WRITE_ONCE(netdev->mtu, new_mtu);
 
 	if (netif_running(netdev)) {
-		iavf_schedule_reset(adapter, IAVF_FLAG_RESET_NEEDED);
-		ret = iavf_wait_for_reset(adapter);
-		if (ret < 0)
-			netdev_warn(netdev, "MTU change interrupted waiting for reset");
-		else if (ret)
-			netdev_warn(netdev, "MTU change timed out waiting for reset");
+		adapter->flags |= IAVF_FLAG_RESET_NEEDED;
+		iavf_reset_step(adapter);
 	}
 
-	return ret;
+	return 0;
 }
 
 /**
-- 
2.52.0