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author | Hiroshi Yamauchi <yamauchi@google.com> | 2014-05-21 21:10:23 -0700 |
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committer | Hiroshi Yamauchi <yamauchi@google.com> | 2014-05-21 21:19:17 -0700 |
commit | 4cba0d979a11f955e6ec3c0f1bf61478af7aa810 (patch) | |
tree | b3e3b61af6bd079989a1bf5259daaa8006af32d4 /runtime/monitor.h | |
parent | 388c6e273018c753d7822d09d7cda0826f0c32ed (diff) | |
download | art-4cba0d979a11f955e6ec3c0f1bf61478af7aa810.tar.gz art-4cba0d979a11f955e6ec3c0f1bf61478af7aa810.tar.bz2 art-4cba0d979a11f955e6ec3c0f1bf61478af7aa810.zip |
Add a read barrier for weak roots in monitors.
A weak root requires a read barrier for the to-space invariant to hold
because the object pointed to by a weak root can't be marked/forwarded
like the one pointed to by a strong root (GC does not know if it's
alive or not at that point) and because, without a read barrier, a
mutator could access it and obtain a from-space reference, which would
violate the to-space invariant.
TODO: do similar for the other types of weak roots.
Bug: 12687968
Change-Id: I563a0fa4f875e0c21ac96f57696959454e13b15a
Diffstat (limited to 'runtime/monitor.h')
-rw-r--r-- | runtime/monitor.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/runtime/monitor.h b/runtime/monitor.h index bc5d2e4bb9..ed1b27b821 100644 --- a/runtime/monitor.h +++ b/runtime/monitor.h @@ -27,6 +27,7 @@ #include "atomic.h" #include "base/mutex.h" #include "object_callbacks.h" +#include "read_barrier.h" #include "thread_state.h" namespace art { @@ -92,8 +93,9 @@ class Monitor { static bool IsValidLockWord(LockWord lock_word); + template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier> mirror::Object* GetObject() const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) { - return obj_; + return ReadBarrier::BarrierForWeakRoot<mirror::Object, kReadBarrierOption>(obj_); } void SetObject(mirror::Object* object); @@ -190,7 +192,9 @@ class Monitor { // Owner's recursive lock depth. int lock_count_ GUARDED_BY(monitor_lock_); - // What object are we part of. + // What object are we part of. This is a weak root. Do not access + // this directly, use GetObject() to read it so it will be guarded + // by a read barrier. mirror::Object* obj_; // Threads currently waiting on this monitor. |