Implement PCI device reset handler to allow the network device to
get re-initialized and function after a PCI-level reset.

This is necessary for the adapter to avoid TX queue timeouts
occurring when the PCI reset is initiated via sysfs during
the operation

Signed-off-by: Sergey Temerkhanov <[email protected]>
Reviewed-by: Aleksandr Loktionov <[email protected]>
---

Previous version: 
https://lore.kernel.org/netdev/mw4pr11mb6864bc9ca84f060af7e0248480...@mw4pr11mb6864.namprd11.prod.outlook.com/
v1->v2 changes: Rearranged the order of operations, switched to 
poll_timeout_us() macro

 drivers/net/ethernet/intel/ixgbe/ixgbe.h      |  1 +
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 82 +++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h 
b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index 594ccb28da20..c4b0c5bb89c6 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -912,6 +912,7 @@ enum ixgbe_state_t {
        __IXGBE_PTP_TX_IN_PROGRESS,
        __IXGBE_RESET_REQUESTED,
        __IXGBE_PHY_INIT_COMPLETE,
+       __IXGBE_PCIE_RESET_IN_PROGRESS,
 };
 
 struct ixgbe_cb {
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c 
b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 2ac274c73d61..0fb64aef223e 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -12352,6 +12352,86 @@ static pci_ers_result_t ixgbe_io_slot_reset(struct 
pci_dev *pdev)
        return result;
 }
 
+/* 1500 us poll interval */
+#define IXGBE_RESET_PREP_POLL_INTERVAL_US 1500
+/* 2 second timeout to acquire reset lock before proceeding */
+#define IXGBE_RESET_PREP_TIMEOUT_US 2000000
+
+/**
+ * ixgbe_reset_prep - called before the pci bus is reset.
+ * @pdev: Pointer to PCI device
+ *
+ * Prepare the card for a reset, preventing the service task from running.
+ */
+static void ixgbe_reset_prep(struct pci_dev *pdev)
+{
+       struct ixgbe_adapter *adapter = pci_get_drvdata(pdev);
+
+       if (!adapter)
+               return;
+
+       if (poll_timeout_us(test_and_set_bit(__IXGBE_RESETTING, 
&adapter->state),
+                           test_bit(__IXGBE_RESETTING, &adapter->state),
+                           IXGBE_RESET_PREP_POLL_INTERVAL_US,
+                           IXGBE_RESET_PREP_TIMEOUT_US, false)) {
+               /* ixgbe_reset_done() will exit early if this happens.
+                * A retry will be needed
+                */
+               e_err(drv, "Timed out waiting for __IXGBE_RESETTING to be 
released. Reset is needed\n");
+               return;
+       }
+
+       /* Sync __IXGBE_RESETTING */
+       smp_mb__after_atomic();
+
+       if (test_bit(__IXGBE_SERVICE_INITED, &adapter->state)) {
+               /* Prevent the service task from being requeued in the timer 
callback */
+               timer_delete_sync(&adapter->service_timer);
+               /* Cancel any possibly queued service task */
+               cancel_work_sync(&adapter->service_task);
+       }
+
+       pci_clear_master(pdev);
+
+       set_bit(__IXGBE_PCIE_RESET_IN_PROGRESS, &adapter->state);
+}
+
+/**
+ * ixgbe_reset_done - called after the pci bus has been reset.
+ * @pdev: Pointer to PCI device
+ *
+ * Allow the service task to run and schedule re-initialization.
+ */
+static void ixgbe_reset_done(struct pci_dev *pdev)
+{
+       struct ixgbe_adapter *adapter = pci_get_drvdata(pdev);
+
+       if (!adapter)
+               return;
+
+       if (!test_and_clear_bit(__IXGBE_PCIE_RESET_IN_PROGRESS, 
&adapter->state)) {
+               /* Should never get here */
+               e_err(drv, "Reset done called without PCIe reset in 
progress\n");
+               return;
+       }
+
+       pci_set_master(pdev);
+
+       /* Allow the service task to run */
+       if (!test_bit(__IXGBE_REMOVING, &adapter->state)) {
+               clear_bit(__IXGBE_RESETTING, &adapter->state);
+               /* Sync __IXGBE_RESETTING */
+               smp_mb__after_atomic();
+       }
+
+       /* Schedule re-initialization */
+       if (!test_bit(__IXGBE_DOWN, &adapter->state)) {
+               set_bit(__IXGBE_RESET_REQUESTED, &adapter->state);
+               if (test_bit(__IXGBE_SERVICE_INITED, &adapter->state))
+                       mod_timer(&adapter->service_timer, jiffies + 1);
+       }
+}
+
 /**
  * ixgbe_io_resume - called when traffic can start flowing again.
  * @pdev: Pointer to PCI device
@@ -12384,6 +12464,8 @@ static const struct pci_error_handlers 
ixgbe_err_handler = {
        .error_detected = ixgbe_io_error_detected,
        .slot_reset = ixgbe_io_slot_reset,
        .resume = ixgbe_io_resume,
+       .reset_prepare = ixgbe_reset_prep,
+       .reset_done = ixgbe_reset_done,
 };
 
 static DEFINE_SIMPLE_DEV_PM_OPS(ixgbe_pm_ops, ixgbe_suspend, ixgbe_resume);
-- 
2.53.0

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