i40evf: fix oops in watchdog handler

The Tx watchdog handler runs in interrupt context, so it would cause an
oops when sending an admin queue message to request a reset, because the
admin queue functions use spinlocks.

Instead, set a flag and let the reset task handle sending the request.

Change-ID: I65879470b72963d9c308edfb8f45ac4fbba2c14f
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40evf/i40evf.h

@@ -211,6 +211,7 @@ struct i40evf_adapter {
 #define I40EVF_FLAG_NEED_LINK_UPDATE             (u32)(1 << 7)
 #define I40EVF_FLAG_PF_COMMS_FAILED              (u32)(1 << 8)
 #define I40EVF_FLAG_RESET_PENDING                (u32)(1 << 9)
+#define I40EVF_FLAG_RESET_NEEDED                 (u32)(1 << 10)
 /* duplcates for common code */
 #define I40E_FLAG_FDIR_ATR_ENABLED		 0
 #define I40E_FLAG_DCB_ENABLED			 0

drivers/net/ethernet/intel/i40evf/i40evf_main.c

@@ -169,9 +169,7 @@ static void i40evf_tx_timeout(struct net_device *netdev)
 	adapter->tx_timeout_count++;
 	dev_info(&adapter->pdev->dev, "TX timeout detected.\n");
 	if (!(adapter->flags & I40EVF_FLAG_RESET_PENDING)) {
-		dev_info(&adapter->pdev->dev, "Requesting reset from PF\n");
-		i40evf_request_reset(adapter);
-		adapter->flags |= I40EVF_FLAG_RESET_PENDING;
+		adapter->flags |= I40EVF_FLAG_RESET_NEEDED;
 		schedule_work(&adapter->reset_task);
 	}
 }
@@ -1484,6 +1482,12 @@ static void i40evf_reset_task(struct work_struct *work)
 	while (test_and_set_bit(__I40EVF_IN_CRITICAL_TASK,
 				&adapter->crit_section))
 		udelay(500);
+
+	if (adapter->flags & I40EVF_FLAG_RESET_NEEDED) {
+		dev_info(&adapter->pdev->dev, "Requesting reset from PF\n");
+		i40evf_request_reset(adapter);
+	}
+
 	/* poll until we see the reset actually happen */
 	for (i = 0; i < I40EVF_RESET_WAIT_COUNT; i++) {
 		rstat_val = rd32(hw, I40E_VFGEN_RSTAT) &