ASan-exempt CrossThreadPersistentRegion::shouldTracePersistentNode().

ASan-exempt CrossThreadPersistentRegion::shouldTracePersistentNode().

CrossThreadPersistent<T>s can reside on heap objects which are lazily
swept. Consequently, when a (per-)thread GC runs and it iterates over the
CrossThreadPersistentRegion to determine what nodes point into its heaps,
it can in the general case also touch lazily sweepable heap objects.

This is a benign read access to a region of memory that Oilpan has poisoned;
therefore, shouldTracePersistentNode() must be exempt from ASan checks to
prevent false negatives from being caught and reported.

R=
BUG=635574
Committed: https://crrev.com/c00a99cd755fb8d985d811fef885a3dcf446abf2
Cr-Commit-Position: refs/heads/master@{#410980}

[sof, 2016-08-09 20:37:44]

The CQ bit was checked by sigbjornf@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2016-08-09 20:38:40]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[sof, 2016-08-09 20:43:46]

sigbjornf@opera.com changed reviewers:
+ oilpan-reviews@chromium.org

[sof, 2016-08-09 20:43:46]

please take a look.

[commit-bot: I haz the power, 2016-08-09 23:42:53]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-09 23:42:54]

Dry run: Try jobs failed on following builders:
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[haraken, 2016-08-10 01:02:47]

LGTM

[sof, 2016-08-10 05:20:57]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2016-08-10 05:21:23]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-10 06:25:02]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-10 06:26:19]

Description was changed from

==========
ASan-exempt CrossThreadPersistentRegion::shouldTracePersistentNode().

CrossThreadPersistent<T>s can reside on heap objects which are lazily
swept. Consequently, when a (per-)thread GC runs and it iterates over the
CrossThreadPersistentRegion to determine what nodes point into its heaps,
it can in the general case also touch lazily sweepable heap objects.

This is a benign read access to a region of memory that Oilpan has poisoned;
therefore, shouldTracePersistentNode() must be exempt from ASan checks to
prevent false negatives from being caught and reported.

R=
BUG=635574
==========

to

==========
ASan-exempt CrossThreadPersistentRegion::shouldTracePersistentNode().

CrossThreadPersistent<T>s can reside on heap objects which are lazily
swept. Consequently, when a (per-)thread GC runs and it iterates over the
CrossThreadPersistentRegion to determine what nodes point into its heaps,
it can in the general case also touch lazily sweepable heap objects.

This is a benign read access to a region of memory that Oilpan has poisoned;
therefore, shouldTracePersistentNode() must be exempt from ASan checks to
prevent false negatives from being caught and reported.

R=
BUG=635574

Committed: https://crrev.com/c00a99cd755fb8d985d811fef885a3dcf446abf2
Cr-Commit-Position: refs/heads/master@{#410980}
==========

[commit-bot: I haz the power, 2016-08-10 06:26:20]

Patchset 1 (id:??) landed as
https://crrev.com/c00a99cd755fb8d985d811fef885a3dcf446abf2
Cr-Commit-Position: refs/heads/master@{#410980}