fm10k: wait for queues to drain if stop_hw() fails once

It turns out that sometimes during a reset the Tx queues will be
temporarily stuck longer than .stop_hw() expects. Work around this issue
by attempting to .stop_hw() first. If it tails, wait a number of
attempts until the Tx queues appear to be drained. After this, attempt
stop_hw() again. This ensures that we avoid waiting if we don't need to,
such as during the first initialization of a VF, and give the proper
amount of time necessary to recover from most situations. It is possible
that the hardware is actually stuck. For PFs, this is usually fixed by
a datapath reset. Unfortunately the VF cannot request a similar reset
for itself.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/fm10k/fm10k.h b/drivers/net/ethernet/intel/fm10k/fm10k.h
index c8d0817766bf661a1bd647d5024cad4ce06a85a2..c4cf08dcf5af97205bc5f0fffa1cadd188f97fec 100644 (file)
--- a/drivers/net/ethernet/intel/fm10k/fm10k.h
+++ b/drivers/net/ethernet/intel/fm10k/fm10k.h
@@ -458,6 +458,7 @@ __be16 fm10k_tx_encap_offload(struct sk_buff *skb);
 netdev_tx_t fm10k_xmit_frame_ring(struct sk_buff *skb,
                                  struct fm10k_ring *tx_ring);
 void fm10k_tx_timeout_reset(struct fm10k_intfc *interface);
+u64 fm10k_get_tx_pending(struct fm10k_ring *ring);
 bool fm10k_check_tx_hang(struct fm10k_ring *tx_ring);
 void fm10k_alloc_rx_buffers(struct fm10k_ring *rx_ring, u16 cleaned_count);
 

diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_main.c b/drivers/net/ethernet/intel/fm10k/fm10k_main.c
index c6a464551577c6321508554d1be85a9b6d85ca61..c85fc98945fa7921909705b42bcaf6674b56148c 100644 (file)
--- a/drivers/net/ethernet/intel/fm10k/fm10k_main.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_main.c
@@ -1128,7 +1128,7 @@ static u64 fm10k_get_tx_completed(struct fm10k_ring *ring)
        return ring->stats.packets;
 }
 
-static u64 fm10k_get_tx_pending(struct fm10k_ring *ring)
+u64 fm10k_get_tx_pending(struct fm10k_ring *ring)
 {
        struct fm10k_intfc *interface = ring->q_vector->interface;
        struct fm10k_hw *hw = &interface->hw;

diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
index 4dfd1284a8dea8c2f3b6c3916decd9035b4c9bc6..7c9b20c6b6c14961daa25d45ca651744b287e2a2 100644 (file)
--- a/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
+++ b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c
@@ -1613,7 +1613,7 @@ void fm10k_down(struct fm10k_intfc *interface)
 {
        struct net_device *netdev = interface->netdev;
        struct fm10k_hw *hw = &interface->hw;
-       int err;
+       int err, i = 0, count = 0;
 
        /* signal that we are down to the interrupt handler and service task */
        if (test_and_set_bit(__FM10K_DOWN, &interface->state))
@@ -1629,9 +1629,6 @@ void fm10k_down(struct fm10k_intfc *interface)
        /* reset Rx filters */
        fm10k_reset_rx_state(interface);
 
-       /* allow 10ms for device to quiesce */
-       usleep_range(10000, 20000);
-
        /* disable polling routines */
        fm10k_napi_disable_all(interface);
 
@@ -1642,11 +1639,46 @@ void fm10k_down(struct fm10k_intfc *interface)
        while (test_and_set_bit(__FM10K_UPDATING_STATS, &interface->state))
                usleep_range(1000, 2000);
 
+       /* skip waiting for TX DMA if we lost PCIe link */
+       if (FM10K_REMOVED(hw->hw_addr))
+               goto skip_tx_dma_drain;
+
+       /* In some rare circumstances it can take a while for Tx queues to
+        * quiesce and be fully disabled. Attempt to .stop_hw() first, and
+        * then if we get ERR_REQUESTS_PENDING, go ahead and wait in a loop
+        * until the Tx queues have emptied, or until a number of retries. If
+        * we fail to clear within the retry loop, we will issue a warning
+        * indicating that Tx DMA is probably hung. Note this means we call
+        * .stop_hw() twice but this shouldn't cause any problems.
+        */
+       err = hw->mac.ops.stop_hw(hw);
+       if (err != FM10K_ERR_REQUESTS_PENDING)
+               goto skip_tx_dma_drain;
+
+#define TX_DMA_DRAIN_RETRIES 25
+       for (count = 0; count < TX_DMA_DRAIN_RETRIES; count++) {
+               usleep_range(10000, 20000);
+
+               /* start checking at the last ring to have pending Tx */
+               for (; i < interface->num_tx_queues; i++)
+                       if (fm10k_get_tx_pending(interface->tx_ring[i]))
+                               break;
+
+               /* if all the queues are drained, we can break now */
+               if (i == interface->num_tx_queues)
+                       break;
+       }
+
+       if (count >= TX_DMA_DRAIN_RETRIES)
+               dev_err(&interface->pdev->dev,
+                       "Tx queues failed to drain after %d tries. Tx DMA is probably hung.\n",
+                       count);
+skip_tx_dma_drain:
        /* Disable DMA engine for Tx/Rx */
        err = hw->mac.ops.stop_hw(hw);
        if (err == FM10K_ERR_REQUESTS_PENDING)
-               dev_info(&interface->pdev->dev,
-                        "due to pending requests hw was not shut down gracefully\n");
+               dev_err(&interface->pdev->dev,
+                       "due to pending requests hw was not shut down gracefully\n");
        else if (err)
                dev_err(&interface->pdev->dev, "stop_hw failed: %d\n", err);