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Remove use of locks in VcnGatewayConnection.

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This CL updates VcnGatewayConnection to not use locking for accesses to
its TelephonySubscriptionSnapshot field. Instead, it will verify that
the caller is running on the VCN-Looper. Because VcnGatewayConnection
also runs on the VCN-Looper, this check guarantees that accesses to that
field are safe even when not explicitly in a Handler event.

Bug: 177364490
Test: atest FrameworksVcnTests
Change-Id: I128a894cead739b88a77e37f4d829d33f6bfb26a
This commit is contained in:
Cody Kesting
2021-02-03 23:40:46 -08:00
parent 204a2fed4f
commit da86336b18
1 changed files with 4 additions and 13 deletions
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17
services/core/java/com/android/server/vcn/VcnGatewayConnection.java
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@@ -61,7 +61,6 @@ import android.os.ParcelUuid;
import android.util.ArraySet;
import android.util.Slog;
import com.android.internal.annotations.GuardedBy;
import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.annotations.VisibleForTesting.Visibility;
import com.android.internal.util.State;
@@ -404,9 +403,6 @@ public class VcnGatewayConnection extends StateMachine {
@NonNull
final RetryTimeoutState mRetryTimeoutState = new RetryTimeoutState();
@NonNull private final Object mLock = new Object();
@GuardedBy("mLock")
@NonNull private TelephonySubscriptionSnapshot mLastSnapshot;
@NonNull private final VcnContext mVcnContext;
@@ -516,9 +512,7 @@ public class VcnGatewayConnection extends StateMachine {
Objects.requireNonNull(gatewayStatusCallback, "Missing gatewayStatusCallback");
mDeps = Objects.requireNonNull(deps, "Missing deps");
synchronized (mLock) {
mLastSnapshot = Objects.requireNonNull(snapshot, "Missing snapshot");
}
mLastSnapshot = Objects.requireNonNull(snapshot, "Missing snapshot");
mUnderlyingNetworkTrackerCallback = new VcnUnderlyingNetworkTrackerCallback();
@@ -589,13 +583,10 @@ public class VcnGatewayConnection extends StateMachine {
*/
public void updateSubscriptionSnapshot(@NonNull TelephonySubscriptionSnapshot snapshot) {
Objects.requireNonNull(snapshot, "Missing snapshot");
mVcnContext.ensureRunningOnLooperThread();
// Vcn is the only user of this method and runs on the same Thread, but lock around
// mLastSnapshot to be technically correct.
synchronized (mLock) {
mLastSnapshot = snapshot;
mUnderlyingNetworkTracker.updateSubscriptionSnapshot(mLastSnapshot);
}
mLastSnapshot = snapshot;
mUnderlyingNetworkTracker.updateSubscriptionSnapshot(mLastSnapshot);
sendMessage(EVENT_SUBSCRIPTIONS_CHANGED, TOKEN_ALL);
}