| commit | dd8f24ee49a7a4a6829b91d54a6db439420298e7 | [log] [tgz] |
|---|---|---|
| author | Martin Kustermann <kustermann@google.com> | Wed Feb 17 09:53:49 2021 +0000 |
| committer | William Hesse <whesse@google.com> | Fri Feb 19 12:25:49 2021 +0100 |
| tree | eb6564e3293d60d23e508df6b586238ffebb5ab0 | |
| parent | dcaded0347cb6a6fa1906c3d52070e0617d4202d [diff] |
[vm/concurrency] Refactor SafepointRwLock to ensure unlocking never causes safepoint transition.
The previous implementation of SafepointRwLock has an issue (discovered
by Slava, see bug) with the following code pattern:
{
SafepointReadRwLocker locker(...);
return Foo(); // <-- Returns raw ptr.
}
After the return expression has been evaluated to a raw pointer
the destructor might enter safepoint and cause GC, which leaves
the raw pointer unchanged (since it's not in a handle).
This CL refactors the implementation to ensure we don't perform any
state transition in the destructor, therefore eliminate the
possibility of GC moving the object we return.
Issue https://github.com/dart-lang/sdk/issues/44998
TEST=Relying on existing SafepointRwLock.
Change-Id: Ib7a62b36838edd4b39ad67a8c58f048aa05aa144
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/185062
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
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