Ignore BPF tethering offload test if tether config is disabled

Needed because OEM can disable BPF offload by PRO.

Bug: 237144191
Bug: 236925089
Test: atest EthernetTetheringTest
Change-Id: Idf965caa44aeaae1f084d2c4fcd516a352c1b138

Tethering/src/com/android/networkstack/tethering/BpfCoordinator.java

@@ -944,6 +944,8 @@ public class BpfCoordinator {
      * be allowed to be accessed on the handler thread.
      */
     public void dump(@NonNull IndentingPrintWriter pw) {
+        // Note that EthernetTetheringTest#isTetherConfigBpfOffloadEnabled relies on
+        // "mIsBpfEnabled" to check tethering config via dumpsys. Beware of the change if any.
         pw.println("mIsBpfEnabled: " + mIsBpfEnabled);
         pw.println("Polling " + (mPollingStarted ? "started" : "not started"));
         pw.println("Stats provider " + (mStatsProvider != null

Tethering/tests/integration/src/android/net/EthernetTetheringTest.java

@@ -1125,12 +1125,18 @@ public class EthernetTetheringTest {
     @IgnoreUpTo(Build.VERSION_CODES.R)
     public void testTetherUdpV4AfterR() throws Exception {
         final String kernelVersion = VintfRuntimeInfo.getKernelVersion();
-        boolean usingBpf = isUdpOffloadSupportedByKernel(kernelVersion);
+        final boolean isUdpOffloadSupported = isUdpOffloadSupportedByKernel(kernelVersion);
-        if (!usingBpf) {
+        if (!isUdpOffloadSupported) {
             Log.i(TAG, "testTetherUdpV4AfterR will skip BPF offload test for kernel "
                     + kernelVersion);
         }
-        runUdp4Test(initTetheringTester(toList(TEST_IP4_ADDR), toList(TEST_IP4_DNS)), usingBpf);
+        final boolean isTetherConfigBpfOffloadEnabled = isTetherConfigBpfOffloadEnabled();
+        if (!isTetherConfigBpfOffloadEnabled) {
+            Log.i(TAG, "testTetherUdpV4AfterR will skip BPF offload test "
+                    + "because tethering config doesn't enable BPF offload.");
+        }
+        runUdp4Test(initTetheringTester(toList(TEST_IP4_ADDR), toList(TEST_IP4_DNS)),
+                isUdpOffloadSupported && isTetherConfigBpfOffloadEnabled);
     }
 
     @Nullable
@@ -1189,6 +1195,21 @@ public class EthernetTetheringTest {
         return null;
     }
 
+    private boolean isTetherConfigBpfOffloadEnabled() throws Exception {
+        final String dumpStr = DumpTestUtils.dumpService(Context.TETHERING_SERVICE, "--short");
+
+        // BPF offload tether config can be overridden by "config_tether_enable_bpf_offload" in
+        // packages/modules/Connectivity/Tethering/res/values/config.xml. OEM may disable config by
+        // RRO to override the enabled default value. Get the tethering config via dumpsys.
+        // $ dumpsys tethering
+        //   mIsBpfEnabled: true
+        boolean enabled = dumpStr.contains("mIsBpfEnabled: true");
+        if (!enabled) {
+            Log.d(TAG, "BPF offload tether config not enabled: " + dumpStr);
+        }
+        return enabled;
+    }
+
     @NonNull
     private Inet6Address getClatIpv6Address(TetheringTester tester, TetheredDevice tethered)
             throws Exception {