commit b8a959b00fe57fc431034f9bea3c7b3380d4b6a5
author Tianjie Xu <xunchang@google.com> Fri Jun 14 15:35:31 2019 -0700
committer Tianjie Xu <xunchang@google.com> Tue Jul 09 16:47:07 2019 -0700
tree dbe96a31cb6b275b6c56c16872ec1acd5b1592d9
parent e1701454b2f46503f5886e09d29645688bea27ca

Add a new key_pressed_mutex

The following variables in recovery ui were protected by
key_queue_mutex. But the purpose of key_queue_mutex is to protect the
key_queue, which will be changed after we already have a key code. So
getting the key pressed should be orthogonal to the key queue. And
adding a mutex will help to avoid deadlocks in b/135078366.

Variables include:
  char key_pressed[KEY_MAX + 1];
  int key_last_down;
  bool key_long_press;
  int key_down_count;
  bool enable_reboot;

Bug: 135078366
Test: boot into recovery and press keys
Change-Id: Ie2cfcf1f2fec49b53f8fac97aa9a2c60f15b84f9

recovery_ui/include/recovery_ui/ui.h

diff --git a/recovery_ui/include/recovery_ui/ui.h b/recovery_ui/include/recovery_ui/ui.h
index 797e2f0..0b29c29 100644
--- a/recovery_ui/include/recovery_ui/ui.h
+++ b/recovery_ui/include/recovery_ui/ui.h
@@ -230,18 +230,22 @@
 
   bool InitScreensaver();
   void SetScreensaverState(ScreensaverState state);
+
   // Key event input queue
   std::mutex key_queue_mutex;
   std::condition_variable key_queue_cond;
   bool key_interrupted_;
   int key_queue[256], key_queue_len;
-  char key_pressed[KEY_MAX + 1];  // under key_queue_mutex
-  int key_last_down;              // under key_queue_mutex
-  bool key_long_press;            // under key_queue_mutex
-  int key_down_count;             // under key_queue_mutex
-  bool enable_reboot;             // under key_queue_mutex
-  int rel_sum;
 
+  // key press events
+  std::mutex key_press_mutex;
+  char key_pressed[KEY_MAX + 1];
+  int key_last_down;
+  bool key_long_press;
+  int key_down_count;
+  bool enable_reboot;
+
+  int rel_sum;
   int consecutive_power_keys;
   int last_key;
 

recovery_ui/ui.cpp

diff --git a/recovery_ui/ui.cpp b/recovery_ui/ui.cpp
index cf0d3b5..51ad169 100644
--- a/recovery_ui/ui.cpp
+++ b/recovery_ui/ui.cpp
@@ -346,7 +346,7 @@
   bool long_press = false;
 
   {
-    std::lock_guard<std::mutex> lg(key_queue_mutex);
+    std::lock_guard<std::mutex> lg(key_press_mutex);
     key_pressed[key_code] = updown;
     if (updown) {
       ++key_down_count;
@@ -393,7 +393,7 @@
   std::this_thread::sleep_for(750ms);  // 750 ms == "long"
   bool long_press = false;
   {
-    std::lock_guard<std::mutex> lg(key_queue_mutex);
+    std::lock_guard<std::mutex> lg(key_press_mutex);
     if (key_last_down == key_code && key_down_count == count) {
       long_press = key_long_press = true;
     }
@@ -518,13 +518,13 @@
 }
 
 bool RecoveryUI::IsKeyPressed(int key) {
-  std::lock_guard<std::mutex> lg(key_queue_mutex);
+  std::lock_guard<std::mutex> lg(key_press_mutex);
   int pressed = key_pressed[key];
   return pressed;
 }
 
 bool RecoveryUI::IsLongPress() {
-  std::lock_guard<std::mutex> lg(key_queue_mutex);
+  std::lock_guard<std::mutex> lg(key_press_mutex);
   bool result = key_long_press;
   return result;
 }
@@ -548,7 +548,7 @@
 
 RecoveryUI::KeyAction RecoveryUI::CheckKey(int key, bool is_long_press) {
   {
-    std::lock_guard<std::mutex> lg(key_queue_mutex);
+    std::lock_guard<std::mutex> lg(key_press_mutex);
     key_long_press = false;
   }
 
@@ -592,6 +592,6 @@
 void RecoveryUI::KeyLongPress(int) {}
 
 void RecoveryUI::SetEnableReboot(bool enabled) {
-  std::lock_guard<std::mutex> lg(key_queue_mutex);
+  std::lock_guard<std::mutex> lg(key_press_mutex);
   enable_reboot = enabled;
 }