Waitkey() is designed to obtain lock "key_queue_mutex" in
the very beginning of function.
int RecoveryUI::WaitKey() {
std::unique_lock<std::mutex> lk(key_queue_mutex);
...
}
However, there's case "key_queue_mutex" being applied again in
waitkey(), thus cause deadlock. There are two reproduce
scenario:
1.Executing "fastboot reboot recovery" in userspace
fastboot
2.Executing "adb reboot fastboot" in recovery os
When entering userspace fastboot/recovery, waitkey()
will wait there for user action. fastboot/adb commands
will trigger ui->interruptkey() to notify the thread
waitkey() in. In the next, waitkey() will move on and call
SetScreenSaveState(), which do LOG(ERROR) in fail case of
brightness set. LOG(ERROR) is designed to print log on
UI. Unfortunately, UI->print() applies lock "key_queue_mutex"
too, so deadlock happen.
Note:
Here is details how lock "key_queue_mutex" applied in
UI->print():
Function Print() call
Function PrintV() call
Function update_screen_locked() call
Function draw_screen_locked() call
Function draw_menu_and_test_buffer_locked() call
Function IsLongPress()
bool RecoveryUI::IsLongPress() {
std::lock_guard<std::mutex> lg(key_queue_mutex);
bool result = key_long_press;
return result;
}
Bug: 135078366
Test: no errors when running "fastboot reboot recovery" in userspace
fastboot & "adb reboot fastboot" in recovery os
Change-Id: Ida6b3c4ba9896a70021373f02a94954f0a60cf31
Signed-off-by: Zhang, GaofengX <gaofengx.zhang@intel.com>
Signed-off-by: Xihua Chen <xihua.chen@intel.com>
852d9fec6d