From d2d5a64aa21cfc548c8c8333d1b36979e5e5a640 Mon Sep 17 00:00:00 2001
From: Mathias Agopian <mathias@google.com>
Date: Mon, 11 Mar 2013 17:59:59 -0700
Subject: [PATCH] workaround a deadlock when taking screenshots into a surface

When disconnecting from BufferQueue, we now drain the queue
except the head (which means in the screenshot case we won't
have to block, but we might not have a buffer to show, this
will appear as an error in the log).

Bug: 8362363
Change-Id: If80989aac3c917beea2ebddf3cbb502849d394da
---
 libs/gui/BufferQueue.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libs/gui/BufferQueue.cpp b/libs/gui/BufferQueue.cpp
index d93c06717..41ee1be92 100644
--- a/libs/gui/BufferQueue.cpp
+++ b/libs/gui/BufferQueue.cpp
@@ -995,7 +995,7 @@ void BufferQueue::freeAllBuffersExceptHeadLocked() {
 }
 
 status_t BufferQueue::drainQueueLocked() {
-    while (mSynchronousMode && !mQueue.isEmpty()) {
+    while (mSynchronousMode && mQueue.size() > 1) {
         mDequeueCondition.wait(mMutex);
         if (mAbandoned) {
             ST_LOGE("drainQueueLocked: BufferQueue has been abandoned!");
@@ -1012,7 +1012,7 @@ status_t BufferQueue::drainQueueLocked() {
 status_t BufferQueue::drainQueueAndFreeBuffersLocked() {
     status_t err = drainQueueLocked();
     if (err == NO_ERROR) {
-        if (mSynchronousMode) {
+        if (mQueue.empty()) {
             freeAllBuffersLocked();
         } else {
             freeAllBuffersExceptHeadLocked();