i40e: rtnl_lock in reset path fixes

Any user-initiated path which eventually calls reset needs
to hold the rtnl_lock, so add functionality to do that.

Be careful not to use the safe reset when cleaning up
from the diagnostic tests, which avoids rtnl_lock
recursion from ethtool.

Protect the reset_task with rtnl_lock, since it runs from a work item.

Change-Id: Ib6e7a3fb2966809db2daf35fd5a123ccdf6f6f0f
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e.h

@@ -502,6 +502,7 @@ int i40e_up(struct i40e_vsi *vsi);
 void i40e_down(struct i40e_vsi *vsi);
 extern const char i40e_driver_name[];
 extern const char i40e_driver_version_str[];
+void i40e_do_reset_safe(struct i40e_pf *pf, u32 reset_flags);
 void i40e_do_reset(struct i40e_pf *pf, u32 reset_flags);
 void i40e_update_stats(struct i40e_vsi *vsi);
 void i40e_update_eth_stats(struct i40e_vsi *vsi);

drivers/net/ethernet/intel/i40e/i40e_debugfs.c

@@ -1462,19 +1462,19 @@ static ssize_t i40e_dbg_command_write(struct file *filp,
 		}
 	} else if (strncmp(cmd_buf, "pfr", 3) == 0) {
 		dev_info(&pf->pdev->dev, "forcing PFR\n");
-		i40e_do_reset(pf, (1 << __I40E_PF_RESET_REQUESTED));
+		i40e_do_reset_safe(pf, (1 << __I40E_PF_RESET_REQUESTED));
 
 	} else if (strncmp(cmd_buf, "corer", 5) == 0) {
 		dev_info(&pf->pdev->dev, "forcing CoreR\n");
-		i40e_do_reset(pf, (1 << __I40E_CORE_RESET_REQUESTED));
+		i40e_do_reset_safe(pf, (1 << __I40E_CORE_RESET_REQUESTED));
 
 	} else if (strncmp(cmd_buf, "globr", 5) == 0) {
 		dev_info(&pf->pdev->dev, "forcing GlobR\n");
-		i40e_do_reset(pf, (1 << __I40E_GLOBAL_RESET_REQUESTED));
+		i40e_do_reset_safe(pf, (1 << __I40E_GLOBAL_RESET_REQUESTED));
 
 	} else if (strncmp(cmd_buf, "empr", 4) == 0) {
 		dev_info(&pf->pdev->dev, "forcing EMPR\n");
-		i40e_do_reset(pf, (1 << __I40E_EMP_RESET_REQUESTED));
+		i40e_do_reset_safe(pf, (1 << __I40E_EMP_RESET_REQUESTED));
 
 	} else if (strncmp(cmd_buf, "read", 4) == 0) {
 		u32 address;

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -4131,6 +4131,19 @@ void i40e_do_reset(struct i40e_pf *pf, u32 reset_flags)
 	}
 }
 
+/**
+ * i40e_do_reset_safe - Protected reset path for userland calls.
+ * @pf: board private structure
+ * @reset_flags: which reset is requested
+ *
+ **/
+void i40e_do_reset_safe(struct i40e_pf *pf, u32 reset_flags)
+{
+	rtnl_lock();
+	i40e_do_reset(pf, reset_flags);
+	rtnl_unlock();
+}
+
 /**
  * i40e_handle_lan_overflow_event - Handler for LAN queue overflow event
  * @pf: board private structure
@@ -4376,6 +4389,7 @@ static void i40e_reset_subtask(struct i40e_pf *pf)
 {
 	u32 reset_flags = 0;
 
+	rtnl_lock();
 	if (test_bit(__I40E_REINIT_REQUESTED, &pf->state)) {
 		reset_flags |= (1 << __I40E_REINIT_REQUESTED);
 		clear_bit(__I40E_REINIT_REQUESTED, &pf->state);
@@ -4398,14 +4412,17 @@ static void i40e_reset_subtask(struct i40e_pf *pf)
 	 */
 	if (test_bit(__I40E_RESET_INTR_RECEIVED, &pf->state)) {
 		i40e_handle_reset_warning(pf);
-		return;
+		goto unlock;
 	}
 
 	/* If we're already down or resetting, just bail */
 	if (reset_flags &&
 	    !test_bit(__I40E_DOWN, &pf->state) &&
 	    !test_bit(__I40E_CONFIG_BUSY, &pf->state))
 		i40e_do_reset(pf, reset_flags);
+
+unlock:
+	rtnl_unlock();
 }
 
 /**