Strengthen the robustness of concurrent operations

1. Ensure the concurrent access to mChannels in Terminal.java
   is protected by the same lock instance
2. Move the remove operation of mSessions into synchronized block
   in method of Terminal.removeSession
3. Add synchronous block protection to mChannels.add operation in
   SecureElementService.java

2 files changed, 15 insertions, 8 deletions

diff --git a/src/com/android/se/SecureElementService.java b/src/com/android/se/SecureElementService.java
index e9a7b39..7f544e3 100755
--- a/src/com/android/se/SecureElementService.java
+++ b/src/com/android/se/SecureElementService.java
@@ -369,7 +369,9 @@ public final class SecureElementService extends Service {
             Log.i(mTag, "Open basic channel success. Channel: "
                     + channel.getChannelNumber());
 
-            mChannels.add(channel);
+            synchronized (mLock) {
+                mChannels.add(channel);
+            }
             return channel.new SecureElementChannel();
         }
 
@@ -409,7 +411,9 @@ public final class SecureElementService extends Service {
             Log.i(mTag, "openLogicalChannel() Success. Channel: "
                     + channel.getChannelNumber());
 
-            mChannels.add(channel);
+            synchronized (mLock) {
+                mChannels.add(channel);
+            }
             return channel.new SecureElementChannel();
         }
     }
diff --git a/src/com/android/se/Terminal.java b/src/com/android/se/Terminal.java
index a6a074b..2153dac 100755
--- a/src/com/android/se/Terminal.java
+++ b/src/com/android/se/Terminal.java
@@ -386,11 +386,13 @@ public class Terminal {
     /**
      * Cleans up all the channels in use.
      */
-    public synchronized void closeChannels() {
-        Collection<Channel> col = mChannels.values();
-        Channel[] channelList = col.toArray(new Channel[col.size()]);
-        for (Channel channel : channelList) {
-            channel.close();
+    public void closeChannels() {
+        synchronized (mLock) {
+            Collection<Channel> col = mChannels.values();
+            Channel[] channelList = col.toArray(new Channel[col.size()]);
+            for (Channel channel : channelList) {
+                channel.close();
+            }
         }
     }
 
@@ -1031,8 +1033,9 @@ public class Terminal {
                     }
                 }
             }
-            mSessions.remove(session);
+
             synchronized (mLock) {
+                mSessions.remove(session);
                 if (mSessions.size() == 0) {
                     mDefaultApplicationSelectedOnBasicChannel = true;
                 }