[PATCH] D87065: Thread safety analysis: Document how try-acquire is handled
Aaron Puchert via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Wed Sep 2 17:55:11 PDT 2020
aaronpuchert created this revision.
aaronpuchert added a reviewer: aaron.ballman.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
aaronpuchert requested review of this revision.
I don't think this is obvious, since try-acquire seemingly contradicts
our usual requirements of "no conditional locking".
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D87065
Files:
clang/docs/ThreadSafetyAnalysis.rst
Index: clang/docs/ThreadSafetyAnalysis.rst
===================================================================
--- clang/docs/ThreadSafetyAnalysis.rst
+++ clang/docs/ThreadSafetyAnalysis.rst
@@ -414,6 +414,26 @@
indicates success, and the remaining arguments are interpreted in the same way
as ``ACQUIRE``. See :ref:`mutexheader`, below, for example uses.
+Because the analysis doesn't support conditional locking, a capability is
+treated as acquired after the first branch on the return value of a try-acquire
+function.
+
+.. code-block:: c++
+
+ Mutex mu;
+ int a GUARDED_BY(mu);
+
+ void foo() {
+ bool success = mu.TryLock();
+ a = 0; // Warning, mu is not locked.
+ if (success) {
+ a = 0; // Ok.
+ mu.Unlock();
+ } else {
+ a = 0; // Warning, mu is not locked.
+ }
+ }
+
ASSERT_CAPABILITY(...) and ASSERT_SHARED_CAPABILITY(...)
--------------------------------------------------------
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