From: tony.ys_liu <tony.ys_liu@htc.com>
Date: Wed, 14 Jan 2015 10:28:03 +0000 (+0800)
Subject: Fix false alarm on thread suspend timeout
X-Git-Tag: android-x86-7.1-r1~889^2~2205^2
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=071e48ecfc95b1c67b07c975190d51f646ac4276;p=android-x86%2Fart.git

Fix false alarm on thread suspend timeout

Root cause:
  CLOCK_REALTIME will jump backward/forward when system time-of-day clock is changed.
  It implies now_abs_ts will jump a lot across end_abs_ts.
  Then, it makes a false alarm (process crash) on thread suspend timeout when doing ComputeRelativeTimeSpec.

      if (ComputeRelativeTimeSpec(&rel_ts, end_abs_ts, now_abs_ts)) {
        return false;  // Timed out.
      }

Solution:
  Use CLOCK_MONOTONIC instead

Change-Id: I768af52b05ee1548bb291f7d5e2f389ec85e0e71
---

diff --git a/runtime/base/mutex.cc b/runtime/base/mutex.cc
index a4eb318d4..17b2ac98c 100644
--- a/runtime/base/mutex.cc
+++ b/runtime/base/mutex.cc
@@ -612,7 +612,7 @@ bool ReaderWriterMutex::ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32
 #if ART_USE_FUTEXES
   bool done = false;
   timespec end_abs_ts;
-  InitTimeSpec(true, CLOCK_REALTIME, ms, ns, &end_abs_ts);
+  InitTimeSpec(true, CLOCK_MONOTONIC, ms, ns, &end_abs_ts);
   do {
     int32_t cur_state = state_.LoadRelaxed();
     if (cur_state == 0) {
@@ -621,7 +621,7 @@ bool ReaderWriterMutex::ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32
     } else {
       // Failed to acquire, hang up.
       timespec now_abs_ts;
-      InitTimeSpec(true, CLOCK_REALTIME, 0, 0, &now_abs_ts);
+      InitTimeSpec(true, CLOCK_MONOTONIC, 0, 0, &now_abs_ts);
       timespec rel_ts;
       if (ComputeRelativeTimeSpec(&rel_ts, end_abs_ts, now_abs_ts)) {
         return false;  // Timed out.