only allow top-stake SN owner hk to stay immune

Author: camfairchild

pallets/subtensor/src/subnets/registration.rs

@@ -2,6 +2,7 @@ use super::*;
 use sp_core::{H256, U256};
 use sp_io::hashing::{keccak_256, sha2_256};
 use sp_runtime::Saturating;
+use substrate_fixed::types::I64F64;
 use system::pallet_prelude::BlockNumberFor;
 
 const LOG_TARGET: &str = "runtime::subtensor::registration";
@@ -424,13 +425,32 @@ impl<T: Config> Pallet<T> {
             return 0; // If there are no neurons in this network.
         }
 
+        // Get SN owner top stake hotkey
+        let mut top_stake_sn_owner_hotkey: Option<T::AccountId> = None;
+        let mut max_stake_weight: I64F64 = I64F64::from_num(-1);
         for neuron_uid in 0..neurons_n {
-            // Do not deregister the owner
             if let Ok(hotkey) = Self::get_hotkey_for_net_and_uid(netuid, neuron_uid) {
                 let coldkey = Self::get_owning_coldkey_for_hotkey(&hotkey);
-                if Self::get_subnet_owner(netuid) == coldkey {
+                if Self::get_subnet_owner(netuid) != coldkey {
                     continue;
                 }
+
+                let stake_weights = Self::get_stake_weights_for_hotkey_on_subnet(&hotkey, netuid);
+                if stake_weights.0 > max_stake_weight {
+                    max_stake_weight = stake_weights.0;
+                    top_stake_sn_owner_hotkey = Some(hotkey);
+                }
+            }
+        }
+
+        for neuron_uid in 0..neurons_n {
+            // Do not deregister the owner's top-stake hotkey
+            if let Ok(hotkey) = Self::get_hotkey_for_net_and_uid(netuid, neuron_uid) {
+                if let Some(ref top_sn_owner_hotkey) = top_stake_sn_owner_hotkey {
+                    if top_sn_owner_hotkey == &hotkey {
+                        continue;
+                    }
+                }
             }
 
             let pruning_score: u16 = Self::get_pruning_score_for_uid(netuid, neuron_uid);