[clang-tools-extra] [clang-tidy] Add check to flag objects hostile to suspension in a coroutine (PR #68738)
Utkarsh Saxena via cfe-commits
cfe-commits at lists.llvm.org
Tue Oct 10 13:04:22 PDT 2023
https://github.com/usx95 created https://github.com/llvm/llvm-project/pull/68738
None
>From f9e29053a7a8fd8222cfbdf579776fafd6564b89 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Tue, 10 Oct 2023 21:53:37 +0200
Subject: [PATCH] [clang-tidy] Add check to flag objects hostile to suspension
in a coroutine
---
.../clang-tidy/misc/CMakeLists.txt | 1 +
.../misc/CoroutineSuspensionHostileCheck.cpp | 79 +++++++++++
.../misc/CoroutineSuspensionHostileCheck.h | 45 ++++++
.../clang-tidy/misc/MiscTidyModule.cpp | 3 +
clang-tools-extra/docs/ReleaseNotes.rst | 6 +
.../docs/clang-tidy/checks/list.rst | 1 +
.../misc/coroutine-suspension-hostile.rst | 36 +++++
.../misc/coroutine-suspension-hostile.cpp | 131 ++++++++++++++++++
8 files changed, 302 insertions(+)
create mode 100644 clang-tools-extra/clang-tidy/misc/CoroutineSuspensionHostileCheck.cpp
create mode 100644 clang-tools-extra/clang-tidy/misc/CoroutineSuspensionHostileCheck.h
create mode 100644 clang-tools-extra/docs/clang-tidy/checks/misc/coroutine-suspension-hostile.rst
create mode 100644 clang-tools-extra/test/clang-tidy/checkers/misc/coroutine-suspension-hostile.cpp
diff --git a/clang-tools-extra/clang-tidy/misc/CMakeLists.txt b/clang-tools-extra/clang-tidy/misc/CMakeLists.txt
index 2e88e68a5447825..c58a99d165dc34c 100644
--- a/clang-tools-extra/clang-tidy/misc/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/misc/CMakeLists.txt
@@ -18,6 +18,7 @@ add_custom_target(genconfusable DEPENDS Confusables.inc)
add_clang_library(clangTidyMiscModule
ConstCorrectnessCheck.cpp
+ CoroutineSuspensionHostileCheck.cpp
DefinitionsInHeadersCheck.cpp
ConfusableIdentifierCheck.cpp
HeaderIncludeCycleCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/misc/CoroutineSuspensionHostileCheck.cpp b/clang-tools-extra/clang-tidy/misc/CoroutineSuspensionHostileCheck.cpp
new file mode 100644
index 000000000000000..d9fb34f5e92888a
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/misc/CoroutineSuspensionHostileCheck.cpp
@@ -0,0 +1,79 @@
+//===--- CoroutineSuspensionHostileCheck.cpp - clang-tidy --------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "CoroutineSuspensionHostileCheck.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/Attrs.inc"
+#include "clang/AST/Decl.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/Stmt.h"
+#include "clang/AST/Type.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::misc {
+CoroutineSuspensionHostileCheck::CoroutineSuspensionHostileCheck(
+ StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context),
+ DenyTypeList(
+ utils::options::parseStringList(Options.get("DenyTypeList", ""))) {}
+
+void CoroutineSuspensionHostileCheck::registerMatchers(MatchFinder *Finder) {
+ // A suspension happens with co_await or co_yield.
+ Finder->addMatcher(coawaitExpr().bind("suspension"), this);
+ Finder->addMatcher(coyieldExpr().bind("suspension"), this);
+}
+
+void CoroutineSuspensionHostileCheck::checkVarDecl(VarDecl *VD) {
+ RecordDecl *RD = VD->getType().getCanonicalType()->getAsRecordDecl();
+ if (RD->hasAttr<clang::ScopedLockableAttr>()) {
+ diag(VD->getLocation(),
+ "%0 holds a lock across a suspension point of coroutine and could be "
+ "unlocked by a different thread")
+ << VD;
+ }
+ if (std::find(DenyTypeList.begin(), DenyTypeList.end(),
+ RD->getQualifiedNameAsString()) != DenyTypeList.end()) {
+ diag(VD->getLocation(),
+ "%0 persists across a suspension point of coroutine")
+ << VD;
+ }
+}
+
+void CoroutineSuspensionHostileCheck::check(
+ const MatchFinder::MatchResult &Result) {
+ const auto *Suspension = Result.Nodes.getNodeAs<Stmt>("suspension");
+ DynTypedNode P;
+ for (const Stmt *Child = Suspension; Child; Child = P.get<Stmt>()) {
+ auto Parents = Result.Context->getParents(*Child);
+ if (Parents.empty())
+ break;
+ P = *Parents.begin();
+ auto *PCS = P.get<CompoundStmt>();
+ if (!PCS)
+ continue;
+ for (auto Sibling = PCS->child_begin();
+ *Sibling != Child && Sibling != PCS->child_end(); ++Sibling) {
+ if (auto *DS = dyn_cast<DeclStmt>(*Sibling)) {
+ for (Decl *D : DS->decls()) {
+ if (VarDecl *VD = dyn_cast<VarDecl>(D)) {
+ checkVarDecl(VD);
+ }
+ }
+ }
+ }
+ }
+}
+
+void CoroutineSuspensionHostileCheck::storeOptions(
+ ClangTidyOptions::OptionMap &Opts) {
+ Options.store(Opts, "DenyTypeList",
+ utils::options::serializeStringList(DenyTypeList));
+}
+} // namespace clang::tidy::misc
diff --git a/clang-tools-extra/clang-tidy/misc/CoroutineSuspensionHostileCheck.h b/clang-tools-extra/clang-tidy/misc/CoroutineSuspensionHostileCheck.h
new file mode 100644
index 000000000000000..1075507416c7c89
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/misc/CoroutineSuspensionHostileCheck.h
@@ -0,0 +1,45 @@
+//===--- HeaderIncludeCycleCheck.h - clang-tidy -----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_COROUTINESUSPENSSIONHOSTILECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_COROUTINESUSPENSSIONHOSTILECHECK_H
+
+#include "../ClangTidyCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "llvm/ADT/StringRef.h"
+#include <vector>
+
+namespace clang::tidy::misc {
+
+/// Check detects objects which should not to persist across suspension points
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/misc/coroutine-hostile-check.html
+class CoroutineSuspensionHostileCheck : public ClangTidyCheck {
+public:
+ CoroutineSuspensionHostileCheck(llvm::StringRef Name,
+ ClangTidyContext *Context);
+
+ bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+ return LangOpts.CPlusPlus20;
+ }
+
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+ void checkVarDecl(VarDecl *VD);
+ // List of fully qualified types which should not persist across a suspension
+ // point in a coroutine.
+ const std::vector<StringRef> DenyTypeList;
+};
+
+} // namespace clang::tidy::misc
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_COROUTINESUSPENSSIONHOSTILECHECK_H
diff --git a/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp b/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
index 92590506e1ec1e6..189fd1a4787a21b 100644
--- a/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/misc/MiscTidyModule.cpp
@@ -11,6 +11,7 @@
#include "../ClangTidyModuleRegistry.h"
#include "ConfusableIdentifierCheck.h"
#include "ConstCorrectnessCheck.h"
+#include "CoroutineSuspensionHostileCheck.h"
#include "DefinitionsInHeadersCheck.h"
#include "HeaderIncludeCycleCheck.h"
#include "IncludeCleanerCheck.h"
@@ -41,6 +42,8 @@ class MiscModule : public ClangTidyModule {
"misc-confusable-identifiers");
CheckFactories.registerCheck<ConstCorrectnessCheck>(
"misc-const-correctness");
+ CheckFactories.registerCheck<CoroutineSuspensionHostileCheck>(
+ "misc-coroutine-suspension-hostile");
CheckFactories.registerCheck<DefinitionsInHeadersCheck>(
"misc-definitions-in-headers");
CheckFactories.registerCheck<HeaderIncludeCycleCheck>(
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 03e5dc6f164af2a..fd5d66f5c809eb1 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -180,6 +180,12 @@ New checks
Detects C++ code where a reference variable is used to extend the lifetime
of a temporary object that has just been constructed.
+- New :doc:`misc-coroutine-suspension-hostile
+ <clang-tidy/checks/misc/coroutine-suspension-hostile>` check.
+
+ Detects when objects of certain hostile types persists across suspension points in a coroutine.
+ Such hostile types include scoped-lockable types and types belonging to a configurable denylist.
+
New check aliases
^^^^^^^^^^^^^^^^^
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 1baabceea06ef48..5047f91e33d67cd 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -241,6 +241,7 @@ Clang-Tidy Checks
:doc:`llvmlibc-restrict-system-libc-headers <llvmlibc/restrict-system-libc-headers>`, "Yes"
:doc:`misc-confusable-identifiers <misc/confusable-identifiers>`,
:doc:`misc-const-correctness <misc/const-correctness>`, "Yes"
+ :doc:`misc-coroutine-suspension-hostile <misc/coroutine-suspension-hostile.html>`_, "Yes"
:doc:`misc-definitions-in-headers <misc/definitions-in-headers>`, "Yes"
:doc:`misc-header-include-cycle <misc/header-include-cycle>`,
:doc:`misc-include-cleaner <misc/include-cleaner>`, "Yes"
diff --git a/clang-tools-extra/docs/clang-tidy/checks/misc/coroutine-suspension-hostile.rst b/clang-tools-extra/docs/clang-tidy/checks/misc/coroutine-suspension-hostile.rst
new file mode 100644
index 000000000000000..123d9a966a0a058
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/misc/coroutine-suspension-hostile.rst
@@ -0,0 +1,36 @@
+.. title:: clang-tidy - misc-coroutine-suspension-hostile
+
+misc-coroutine-suspension-hostile
+====================
+
+This check detects when objects of certain hostile types persists across suspension points in a coroutine.
+Such hostile types include scoped-lockable types and types belonging to a configurable denylist.
+
+A scoped-lockable object persisting across a suspension point in a coroutine is
+problematic as it is possible for the lock held by this object at the suspension
+point to be unlocked by a wrong thread if the coroutine resume on a different thread.
+This would be undefined behaviour.
+
+The check also diagnosis objects persisting across suspension points which belong to a configurable denylist.
+
+.. code-block:: c++
+
+ // Call some async API while holding a lock.
+ {
+ const my::MutexLock l(&mu_);
+
+ // Oops! The async Bar function may finish on a different
+ // thread from the one that created the MutexLock object and therefore called
+ // Mutex::Lock -- now Mutex::Unlock will be called on the wrong thread.
+ co_await Bar();
+ }
+
+
+Options
+-------
+
+.. option:: DenyTypeList
+
+ A semicolon-separated list of qualified types which should not be allowed to persist across suspension points.
+ Do not include trailing `::` in the qualified name.
+ Eg: `my::lockable; my::other::lockable;`
\ No newline at end of file
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/coroutine-suspension-hostile.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/coroutine-suspension-hostile.cpp
new file mode 100644
index 000000000000000..987339816b4bdc4
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc/coroutine-suspension-hostile.cpp
@@ -0,0 +1,131 @@
+// RUN: %check_clang_tidy -std=c++20 %s misc-coroutine-suspension-hostile %t \
+// RUN: -config="{CheckOptions: \
+// RUN: {misc-coroutine-suspension-hostile.DenyTypeList: \
+// RUN: 'my::Mutex; my::other::Mutex'}}"
+
+namespace std {
+
+template <typename R, typename...> struct coroutine_traits {
+ using promise_type = typename R::promise_type;
+};
+
+template <typename Promise = void> struct coroutine_handle;
+
+template <> struct coroutine_handle<void> {
+ static coroutine_handle from_address(void *addr) noexcept {
+ coroutine_handle me;
+ me.ptr = addr;
+ return me;
+ }
+ void operator()() { resume(); }
+ void *address() const noexcept { return ptr; }
+ void resume() const { }
+ void destroy() const { }
+ bool done() const { return true; }
+ coroutine_handle &operator=(decltype(nullptr)) {
+ ptr = nullptr;
+ return *this;
+ }
+ coroutine_handle(decltype(nullptr)) : ptr(nullptr) {}
+ coroutine_handle() : ptr(nullptr) {}
+ // void reset() { ptr = nullptr; } // add to P0057?
+ explicit operator bool() const { return ptr; }
+
+protected:
+ void *ptr;
+};
+
+template <typename Promise> struct coroutine_handle : coroutine_handle<> {
+ using coroutine_handle<>::operator=;
+
+ static coroutine_handle from_address(void *addr) noexcept {
+ coroutine_handle me;
+ me.ptr = addr;
+ return me;
+ }
+
+ Promise &promise() const {
+ return *reinterpret_cast<Promise *>(
+ __builtin_coro_promise(ptr, alignof(Promise), false));
+ }
+ static coroutine_handle from_promise(Promise &promise) {
+ coroutine_handle p;
+ p.ptr = __builtin_coro_promise(&promise, alignof(Promise), true);
+ return p;
+ }
+};
+
+struct suspend_always {
+ bool await_ready() noexcept { return false; }
+ void await_suspend(std::coroutine_handle<>) noexcept {}
+ void await_resume() noexcept {}
+};
+} // namespace std
+
+struct ReturnObject {
+ struct promise_type {
+ ReturnObject get_return_object() { return {}; }
+ std::suspend_always initial_suspend() { return {}; }
+ std::suspend_always final_suspend() noexcept { return {}; }
+ void unhandled_exception() {}
+ std::suspend_always yield_value(int value) { return {}; }
+ };
+};
+
+
+#define SCOPED_LOCKABLE __attribute__ ((scoped_lockable))
+
+namespace absl {
+class SCOPED_LOCKABLE Mutex {};
+using Mutex2 = Mutex;
+} // namespace absl
+
+
+ReturnObject scopedLockableTest() {
+ absl::Mutex a;
+ // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: 'a' holds a lock across a suspension point of coroutine and could be unlocked by a different thread [misc-coroutine-suspension-hostile]
+ absl::Mutex2 b;
+ // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: 'b' holds a lock across a suspension point of coroutine and could be unlocked by a different thread [misc-coroutine-suspension-hostile]
+ {
+ absl::Mutex no_warning_1;
+ { absl::Mutex no_warning_2; }
+ }
+
+ co_yield 1;
+ absl::Mutex c;
+ // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: 'c' holds a lock across a suspension point of coroutine and could be unlocked by a different thread [misc-coroutine-suspension-hostile]
+ co_await std::suspend_always{};
+ for(int i=1;i<=10;++i ) {
+ absl::Mutex d;
+ // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: 'd' holds a lock across a suspension point of coroutine and could be unlocked by a different thread [misc-coroutine-suspension-hostile]
+ co_await std::suspend_always{};
+ co_yield 1;
+ absl::Mutex no_warning_3;
+ }
+ if (true) {
+ absl::Mutex e;
+ // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: 'e' holds a lock across a suspension point of coroutine and could be unlocked by a different thread [misc-coroutine-suspension-hostile]
+ co_yield 1;
+ absl::Mutex no_warning_4;
+ }
+ absl::Mutex no_warning_5;
+}
+namespace my {
+class Mutex{};
+
+namespace other {
+class Mutex{};
+} // namespace other
+
+using Mutex2 = Mutex;
+} // namespace my
+
+ReturnObject denyListTest() {
+ my::Mutex a;
+ // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: 'a' persists across a suspension point of coroutine [misc-coroutine-suspension-hostile]
+ my::other::Mutex b;
+ // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: 'b' persists across a suspension point of coroutine [misc-coroutine-suspension-hostile]
+ my::Mutex2 c;
+ // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: 'c' persists across a suspension point of coroutine [misc-coroutine-suspension-hostile]
+ co_yield 1;
+}
\ No newline at end of file
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