diff --git a/include/private/ui/SharedBufferStack.h b/include/private/ui/SharedBufferStack.h
index 6181f55..8b0f154 100644
--- a/include/private/ui/SharedBufferStack.h
+++ b/include/private/ui/SharedBufferStack.h
@@ -228,6 +228,8 @@
     friend struct Condition;
     friend struct DequeueCondition;
     friend struct LockCondition;
+    
+    int32_t computeTail() const;
 
     struct QueueUpdate : public UpdateBase {
         inline QueueUpdate(SharedBufferBase* sbb);
diff --git a/include/utils/threads.h b/include/utils/threads.h
index f5304f7..0fc533f 100644
--- a/include/utils/threads.h
+++ b/include/utils/threads.h
@@ -90,11 +90,6 @@
     ANDROID_TGROUP_MAX              = ANDROID_TGROUP_FG_BOOST,
 };
 
-typedef enum {
-    SP_BACKGROUND = 0,
-    SP_FOREGROUND = 1,
-} SchedPolicy;
-
 // Create and run a new thread.
 extern int androidCreateThread(android_thread_func_t, void *);
 
diff --git a/libs/surfaceflinger/SurfaceFlinger.cpp b/libs/surfaceflinger/SurfaceFlinger.cpp
index 8685f99..a352431 100644
--- a/libs/surfaceflinger/SurfaceFlinger.cpp
+++ b/libs/surfaceflinger/SurfaceFlinger.cpp
@@ -1524,13 +1524,24 @@
                 result.append( l->lcblk->dump("      ") );
                 sp<const Buffer> buf0(l->getBuffer(0));
                 sp<const Buffer> buf1(l->getBuffer(1));
+                uint32_t w0=0, h0=0, s0=0;
+                uint32_t w1=0, h1=0, s1=0;
+                if (buf0 != 0) {
+                    w0 = buf0->getWidth();
+                    h0 = buf0->getHeight();
+                    s0 = buf0->getStride();
+                }
+                if (buf1 != 0) {
+                    w1 = buf1->getWidth();
+                    h1 = buf1->getHeight();
+                    s1 = buf1->getStride();
+                }
                 snprintf(buffer, SIZE,
                         "      "
                         "format=%2d, [%3ux%3u:%3u] [%3ux%3u:%3u],"
                         " freezeLock=%p\n",
                         l->pixelFormat(),
-                        buf0->getWidth(), buf0->getHeight(), buf0->getStride(),
-                        buf1->getWidth(), buf1->getHeight(), buf1->getStride(),
+                        w0, h0, s0, w1, h1, s1,
                         l->getFreezeLock().get());
                 result.append(buffer);
                 buffer[0] = 0;
diff --git a/libs/ui/SharedBufferStack.cpp b/libs/ui/SharedBufferStack.cpp
index 436d793..7789a3f 100644
--- a/libs/ui/SharedBufferStack.cpp
+++ b/libs/ui/SharedBufferStack.cpp
@@ -246,19 +246,26 @@
         int surface, int num)
     : SharedBufferBase(sharedClient, surface, num), tail(0)
 {
+    tail = computeTail();
+}
+
+int32_t SharedBufferClient::computeTail() const
+{
     SharedBufferStack& stack( *mSharedStack );
-    int32_t avail;
-    int32_t head;
     // we need to make sure we read available and head coherently,
     // w.r.t RetireUpdate.
+    int32_t newTail;
+    int32_t avail;
+    int32_t head;
     do {
         avail = stack.available;
         head = stack.head;
     } while (stack.available != avail);
-    tail = head - avail + 1;
-    if (tail < 0) {
-        tail += num;
+    newTail = head - avail + 1;
+    if (newTail < 0) {
+        newTail += mNumBuffers;
     }
+    return newTail;
 }
 
 ssize_t SharedBufferClient::dequeue()
@@ -296,6 +303,9 @@
 {
     UndoDequeueUpdate update(this);
     status_t err = updateCondition( update );
+    if (err == NO_ERROR) {
+        tail = computeTail();
+    }
     return err;
 }