diff --git a/core/java/android/net/ConnectivityManager.java b/core/java/android/net/ConnectivityManager.java
index 4a64128..6ba4a30 100644
--- a/core/java/android/net/ConnectivityManager.java
+++ b/core/java/android/net/ConnectivityManager.java
@@ -3234,7 +3234,7 @@
          *
          * @hide
          */
-        public void onPreCheck(Network network) {}
+        public void onPreCheck(@NonNull Network network) {}
 
         /**
          * Called when the framework connects and has declared a new network ready for use.
@@ -3247,8 +3247,9 @@
          * @param blocked Whether access to the {@link Network} is blocked due to system policy.
          * @hide
          */
-        public void onAvailable(Network network, NetworkCapabilities networkCapabilities,
-                LinkProperties linkProperties, boolean blocked) {
+        public void onAvailable(@NonNull Network network,
+                @NonNull NetworkCapabilities networkCapabilities,
+                @NonNull LinkProperties linkProperties, boolean blocked) {
             // Internally only this method is called when a new network is available, and
             // it calls the callback in the same way and order that older versions used
             // to call so as not to change the behavior.
@@ -3272,7 +3273,7 @@
          *
          * @param network The {@link Network} of the satisfying network.
          */
-        public void onAvailable(Network network) {}
+        public void onAvailable(@NonNull Network network) {}
 
         /**
          * Called when the network is about to be disconnected.  Often paired with an
@@ -3288,7 +3289,7 @@
          *                     network connected.  Note that the network may suffer a
          *                     hard loss at any time.
          */
-        public void onLosing(Network network, int maxMsToLive) {}
+        public void onLosing(@NonNull Network network, int maxMsToLive) {}
 
         /**
          * Called when the framework has a hard loss of the network or when the
@@ -3296,7 +3297,7 @@
          *
          * @param network The {@link Network} lost.
          */
-        public void onLost(Network network) {}
+        public void onLost(@NonNull Network network) {}
 
         /**
          * Called if no network is found in the timeout time specified in
@@ -3316,8 +3317,8 @@
          * @param networkCapabilities The new {@link android.net.NetworkCapabilities} for this
          *                            network.
          */
-        public void onCapabilitiesChanged(Network network,
-                NetworkCapabilities networkCapabilities) {}
+        public void onCapabilitiesChanged(@NonNull Network network,
+                @NonNull NetworkCapabilities networkCapabilities) {}
 
         /**
          * Called when the network the framework connected to for this request
@@ -3326,7 +3327,8 @@
          * @param network The {@link Network} whose link properties have changed.
          * @param linkProperties The new {@link LinkProperties} for this network.
          */
-        public void onLinkPropertiesChanged(Network network, LinkProperties linkProperties) {}
+        public void onLinkPropertiesChanged(@NonNull Network network,
+                @NonNull LinkProperties linkProperties) {}
 
         /**
          * Called when the network the framework connected to for this request
@@ -3337,7 +3339,7 @@
          * a tunnel, etc.
          * @hide
          */
-        public void onNetworkSuspended(Network network) {}
+        public void onNetworkSuspended(@NonNull Network network) {}
 
         /**
          * Called when the network the framework connected to for this request
@@ -3345,7 +3347,7 @@
          * preceded by a matching {@link NetworkCallback#onNetworkSuspended} call.
          * @hide
          */
-        public void onNetworkResumed(Network network) {}
+        public void onNetworkResumed(@NonNull Network network) {}
 
         /**
          * Called when access to the specified network is blocked or unblocked.
diff --git a/core/java/android/net/LinkProperties.java b/core/java/android/net/LinkProperties.java
index 03d6d48..ad67763 100644
--- a/core/java/android/net/LinkProperties.java
+++ b/core/java/android/net/LinkProperties.java
@@ -316,9 +316,6 @@
     @SystemApi
     @TestApi
     public boolean removeLinkAddress(@NonNull LinkAddress toRemove) {
-        if (toRemove == null) {
-            return false;
-        }
         int i = findLinkAddressIndex(toRemove);
         if (i >= 0) {
             mLinkAddresses.remove(i);
@@ -391,10 +388,7 @@
     @TestApi
     @SystemApi
     public boolean removeDnsServer(@NonNull InetAddress dnsServer) {
-        if (dnsServer != null) {
-            return mDnses.remove(dnsServer);
-        }
-        return false;
+        return mDnses.remove(dnsServer);
     }
 
     /**
diff --git a/core/java/android/net/NetworkRequest.java b/core/java/android/net/NetworkRequest.java
index 3a41a07..acafa13 100644
--- a/core/java/android/net/NetworkRequest.java
+++ b/core/java/android/net/NetworkRequest.java
@@ -17,6 +17,7 @@
 package android.net;
 
 import android.annotation.NonNull;
+import android.annotation.RequiresPermission;
 import android.annotation.SystemApi;
 import android.annotation.UnsupportedAppUsage;
 import android.net.NetworkCapabilities.NetCapability;
@@ -343,10 +344,14 @@
          * current value. A value of {@code SIGNAL_STRENGTH_UNSPECIFIED} means no value when
          * received and has no effect when requesting a callback.
          *
+         * <p>This method requires the caller to hold the
+         * {@link android.Manifest.permission#NETWORK_SIGNAL_STRENGTH_WAKEUP} permission
+         *
          * @param signalStrength the bearer-specific signal strength.
          * @hide
          */
         @SystemApi
+        @RequiresPermission(android.Manifest.permission.NETWORK_SIGNAL_STRENGTH_WAKEUP)
         public @NonNull Builder setSignalStrength(int signalStrength) {
             mNetworkCapabilities.setSignalStrength(signalStrength);
             return this;
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index bd93184..946c81f 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -1892,6 +1892,15 @@
         return false;
     }
 
+    private boolean checkAnyPermissionOf(int pid, int uid, String... permissions) {
+        for (String permission : permissions) {
+            if (mContext.checkPermission(permission, pid, uid) == PERMISSION_GRANTED) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     private void enforceAnyPermissionOf(String... permissions) {
         if (!checkAnyPermissionOf(permissions)) {
             throw new SecurityException("Requires one of the following permissions: "
@@ -1966,6 +1975,12 @@
                 NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
     }
 
+    private boolean checkNetworkSignalStrengthWakeupPermission(int pid, int uid) {
+        return checkAnyPermissionOf(pid, uid,
+                android.Manifest.permission.NETWORK_SIGNAL_STRENGTH_WAKEUP,
+                NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK);
+    }
+
     private void enforceConnectivityRestrictedNetworksPermission() {
         try {
             mContext.enforceCallingOrSelfPermission(
@@ -3738,16 +3753,6 @@
                     break;
                 }
                 case EVENT_SYSTEM_READY: {
-                    for (NetworkAgentInfo nai : mNetworkAgentInfos.values()) {
-                        // Might have been called already in handleRegisterNetworkAgent since
-                        // mSystemReady is set before sending EVENT_SYSTEM_READY, but calling
-                        // this several times is fine.
-                        try {
-                            nai.networkMonitor().notifySystemReady();
-                        } catch (RemoteException e) {
-                            e.rethrowFromSystemServer();
-                        }
-                    }
                     mMultipathPolicyTracker.start();
                     break;
                 }
@@ -4969,13 +4974,19 @@
         }
     }
 
-    // This checks that the passed capabilities either do not request a specific SSID, or the
-    // calling app has permission to do so.
+    // This checks that the passed capabilities either do not request a specific SSID/SignalStrength
+    // , or the calling app has permission to do so.
     private void ensureSufficientPermissionsForRequest(NetworkCapabilities nc,
             int callerPid, int callerUid) {
         if (null != nc.getSSID() && !checkSettingsPermission(callerPid, callerUid)) {
             throw new SecurityException("Insufficient permissions to request a specific SSID");
         }
+
+        if (nc.hasSignalStrength()
+                && !checkNetworkSignalStrengthWakeupPermission(callerPid, callerUid)) {
+            throw new SecurityException(
+                    "Insufficient permissions to request a specific signal strength");
+        }
     }
 
     private ArrayList<Integer> getSignalStrengthThresholds(NetworkAgentInfo nai) {
@@ -5423,15 +5434,6 @@
         synchronized (mNetworkForNetId) {
             mNetworkForNetId.put(nai.network.netId, nai);
         }
-        synchronized (this) {
-            if (mSystemReady) {
-                try {
-                    networkMonitor.notifySystemReady();
-                } catch (RemoteException e) {
-                    e.rethrowFromSystemServer();
-                }
-            }
-        }
 
         try {
             networkMonitor.start();
diff --git a/services/core/java/com/android/server/connectivity/KeepaliveTracker.java b/services/core/java/com/android/server/connectivity/KeepaliveTracker.java
index d7a57b9..35f7ea3 100644
--- a/services/core/java/com/android/server/connectivity/KeepaliveTracker.java
+++ b/services/core/java/com/android/server/connectivity/KeepaliveTracker.java
@@ -132,6 +132,7 @@
         private static final int NOT_STARTED = 1;
         private static final int STARTING = 2;
         private static final int STARTED = 3;
+        private static final int STOPPING = 4;
         private int mStartedState = NOT_STARTED;
 
         KeepaliveInfo(@NonNull ISocketKeepaliveCallback callback,
@@ -314,6 +315,7 @@
                 }
             }
             if (NOT_STARTED != mStartedState) {
+                mStartedState = STOPPING;
                 Log.d(TAG, "Stopping keepalive " + mSlot + " on " + mNai.name());
                 if (mType == TYPE_NATT) {
                     mNai.asyncChannel.sendMessage(CMD_STOP_SOCKET_KEEPALIVE, mSlot);
@@ -456,8 +458,8 @@
             ki = mKeepalives.get(nai).get(slot);
         } catch(NullPointerException e) {}
         if (ki == null) {
-            Log.e(TAG, "Event " + message.what + " for unknown keepalive " + slot + " on "
-                    + nai.name());
+            Log.e(TAG, "Event " + message.what + "," + slot + "," + reason
+                    + " for unknown keepalive " + slot + " on " + nai.name());
             return;
         }
 
@@ -476,27 +478,30 @@
         // messages in order.
         // TODO : clarify this code and get rid of mStartedState. Using a StateMachine is an
         // option.
-        if (reason == SUCCESS && KeepaliveInfo.STARTING == ki.mStartedState) {
-            // Keepalive successfully started.
-            if (DBG) Log.d(TAG, "Started keepalive " + slot + " on " + nai.name());
-            ki.mStartedState = KeepaliveInfo.STARTED;
-            try {
-                ki.mCallback.onStarted(slot);
-            } catch (RemoteException e) {
-                Log.w(TAG, "Discarded onStarted(" + slot + ") callback");
-            }
-        } else {
-            // Keepalive successfully stopped, or error.
-            if (reason == SUCCESS) {
-                // The message indicated success stopping : don't call handleStopKeepalive.
-                if (DBG) Log.d(TAG, "Successfully stopped keepalive " + slot + " on " + nai.name());
+        if (KeepaliveInfo.STARTING == ki.mStartedState) {
+            if (SUCCESS == reason) {
+                // Keepalive successfully started.
+                if (DBG) Log.d(TAG, "Started keepalive " + slot + " on " + nai.name());
+                ki.mStartedState = KeepaliveInfo.STARTED;
+                try {
+                    ki.mCallback.onStarted(slot);
+                } catch (RemoteException e) {
+                    Log.w(TAG, "Discarded onStarted(" + slot + ") callback");
+                }
             } else {
-                // The message indicated some error trying to start or during the course of
-                // keepalive : do call handleStopKeepalive.
+                Log.d(TAG, "Failed to start keepalive " + slot + " on " + nai.name()
+                        + ": " + reason);
+                // The message indicated some error trying to start: do call handleStopKeepalive.
                 handleStopKeepalive(nai, slot, reason);
-                if (DBG) Log.d(TAG, "Keepalive " + slot + " on " + nai.name() + " error " + reason);
             }
+        } else if (KeepaliveInfo.STOPPING == ki.mStartedState) {
+            // The message indicated result of stopping : don't call handleStopKeepalive.
+            Log.d(TAG, "Stopped keepalive " + slot + " on " + nai.name()
+                    + " stopped: " + reason);
             ki.mStartedState = KeepaliveInfo.NOT_STARTED;
+        } else {
+            Log.wtf(TAG, "Event " + message.what + "," + slot + "," + reason
+                    + " for keepalive in wrong state: " + ki.toString());
         }
     }
 
diff --git a/tests/net/java/android/net/IpPrefixTest.java b/tests/net/java/android/net/IpPrefixTest.java
index 3cc0e36..abf019a 100644
--- a/tests/net/java/android/net/IpPrefixTest.java
+++ b/tests/net/java/android/net/IpPrefixTest.java
@@ -231,7 +231,6 @@
         assertFalse(p.contains(Address("2001:db8:f00::ace:d00e")));
         assertFalse(p.contains(Address("2001:db8:f00::bad:d00d")));
         assertFalse(p.contains(Address("2001:4868:4860::8888")));
-        assertFalse(p.contains((InetAddress)null));
         assertFalse(p.contains(Address("8.8.8.8")));
 
         p = new IpPrefix("192.0.2.0/23");
diff --git a/tests/net/java/com/android/server/ConnectivityServiceTest.java b/tests/net/java/com/android/server/ConnectivityServiceTest.java
index 46a8955..c2fc0b3 100644
--- a/tests/net/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/net/java/com/android/server/ConnectivityServiceTest.java
@@ -3047,6 +3047,47 @@
     }
 
     @Test
+    public void testInvalidSignalStrength() {
+        NetworkRequest r = new NetworkRequest.Builder()
+                .addCapability(NET_CAPABILITY_INTERNET)
+                .addTransportType(TRANSPORT_WIFI)
+                .setSignalStrength(-75)
+                .build();
+        // Registering a NetworkCallback with signal strength but w/o NETWORK_SIGNAL_STRENGTH_WAKEUP
+        // permission should get SecurityException.
+        try {
+            mCm.registerNetworkCallback(r, new NetworkCallback());
+            fail("Expected SecurityException filing a callback with signal strength");
+        } catch (SecurityException expected) {
+            // expected
+        }
+
+        try {
+            mCm.registerNetworkCallback(r, PendingIntent.getService(
+                    mServiceContext, 0, new Intent(), 0));
+            fail("Expected SecurityException filing a callback with signal strength");
+        } catch (SecurityException expected) {
+            // expected
+        }
+
+        // Requesting a Network with signal strength should get IllegalArgumentException.
+        try {
+            mCm.requestNetwork(r, new NetworkCallback());
+            fail("Expected IllegalArgumentException filing a request with signal strength");
+        } catch (IllegalArgumentException expected) {
+            // expected
+        }
+
+        try {
+            mCm.requestNetwork(r, PendingIntent.getService(
+                    mServiceContext, 0, new Intent(), 0));
+            fail("Expected IllegalArgumentException filing a request with signal strength");
+        } catch (IllegalArgumentException expected) {
+            // expected
+        }
+    }
+
+    @Test
     public void testRegisterDefaultNetworkCallback() throws Exception {
         final TestNetworkCallback defaultNetworkCallback = new TestNetworkCallback();
         mCm.registerDefaultNetworkCallback(defaultNetworkCallback);