i40e: recalculate vsi->active_filters from hash contents

Previous code refactors have accidentally caused issues with the
counting of active_filters. Avoid similar issues in the future by simply
re-counting the active filters every time after we handle add and delete
of all the filters. Additionally this allows us to simplify the check
for when we exit promiscuous mode since we can combine the check for
failed filters at the same time.

Additionally since we recount filters at the end we need to set
vsi->promisc_threshold as well.

The resulting code takes a bit longer since we do have to loop over
filters again. However, the result is more readable and less likely to
become incorrect due to failed accounting of filters in the future.
Finally, this ensures that it is not possible for vsi->active_filters to
ever underflow since we never decrement it.

Change-ID: Ib4f3a377e60eb1fa6c91ea86cc02238c08edd102
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -1870,12 +1870,10 @@ void i40e_aqc_add_filters(struct i40e_vsi *vsi, const char *vsi_name,
 	aq_ret = i40e_aq_add_macvlan(hw, vsi->seid, list, num_add, NULL);
 	aq_err = hw->aq.asq_last_status;
 	fcnt = i40e_update_filter_state(num_add, list, add_head, aq_ret);
-	vsi->active_filters += fcnt;
 
 	if (fcnt != num_add) {
 		*promisc_changed = true;
 		set_bit(__I40E_FILTER_OVERFLOW_PROMISC, &vsi->state);
-		vsi->promisc_threshold = (vsi->active_filters * 3) / 4;
 		dev_warn(&vsi->back->pdev->dev,
 			 "Error %s adding RX filters on %s, promiscuous mode forced on\n",
 			 i40e_aq_str(hw, aq_err),
@@ -1939,6 +1937,7 @@ int i40e_sync_vsi_filters(struct i40e_vsi *vsi)
 	struct i40e_hw *hw = &vsi->back->hw;
 	unsigned int vlan_any_filters = 0;
 	unsigned int non_vlan_filters = 0;
+	unsigned int failed_filters = 0;
 	unsigned int vlan_filters = 0;
 	bool promisc_changed = false;
 	char vsi_name[16] = "PF";
@@ -1985,7 +1984,6 @@ int i40e_sync_vsi_filters(struct i40e_vsi *vsi)
 				/* Move the element into temporary del_list */
 				hash_del(&f->hlist);
 				hlist_add_head(&f->hlist, &tmp_del_list);
-				vsi->active_filters--;
 
 				/* Avoid counting removed filters */
 				continue;
@@ -2046,7 +2044,6 @@ int i40e_sync_vsi_filters(struct i40e_vsi *vsi)
 				f->state = I40E_FILTER_REMOVE;
 				hash_del(&f->hlist);
 				hlist_add_head(&f->hlist, &tmp_del_list);
-				vsi->active_filters--;
 			}
 
 			/* Also update any filters on the tmp_add list */
@@ -2203,27 +2200,36 @@ int i40e_sync_vsi_filters(struct i40e_vsi *vsi)
 		add_list = NULL;
 	}
 
-	/* Check to see if we can drop out of overflow promiscuous mode. */
+	/* Determine the number of active and failed filters. */
+	spin_lock_bh(&vsi->mac_filter_hash_lock);
+	vsi->active_filters = 0;
+	hash_for_each(vsi->mac_filter_hash, bkt, f, hlist) {
+		if (f->state == I40E_FILTER_ACTIVE)
+			vsi->active_filters++;
+		else if (f->state == I40E_FILTER_FAILED)
+			failed_filters++;
+	}
+	spin_unlock_bh(&vsi->mac_filter_hash_lock);
+
+	/* If promiscuous mode has changed, we need to calculate a new
+	 * threshold for when we are safe to exit
+	 */
+	if (promisc_changed)
+		vsi->promisc_threshold = (vsi->active_filters * 3) / 4;
+
+	/* Check if we are able to exit overflow promiscuous mode. We can
+	 * safely exit if we didn't just enter, we no longer have any failed
+	 * filters, and we have reduced filters below the threshold value.
+	 */
 	if (test_bit(__I40E_FILTER_OVERFLOW_PROMISC, &vsi->state) &&
+	    !promisc_changed && !failed_filters &&
 	    (vsi->active_filters < vsi->promisc_threshold)) {
-		int failed_count = 0;
-		/* See if we have any failed filters. We can't drop out of
-		 * promiscuous until these have all been deleted.
-		 */
-		spin_lock_bh(&vsi->mac_filter_hash_lock);
-		hash_for_each(vsi->mac_filter_hash, bkt, f, hlist) {
-			if (f->state == I40E_FILTER_FAILED)
-				failed_count++;
-		}
-		spin_unlock_bh(&vsi->mac_filter_hash_lock);
-		if (!failed_count) {
-			dev_info(&pf->pdev->dev,
-				 "filter logjam cleared on %s, leaving overflow promiscuous mode\n",
-				 vsi_name);
-			clear_bit(__I40E_FILTER_OVERFLOW_PROMISC, &vsi->state);
-			promisc_changed = true;
-			vsi->promisc_threshold = 0;
-		}
+		dev_info(&pf->pdev->dev,
+			 "filter logjam cleared on %s, leaving overflow promiscuous mode\n",
+			 vsi_name);
+		clear_bit(__I40E_FILTER_OVERFLOW_PROMISC, &vsi->state);
+		promisc_changed = true;
+		vsi->promisc_threshold = 0;
 	}
 
 	/* if the VF is not trusted do not do promisc */