zdtorok created this revision.
zdtorok added reviewers: zaks.anna, dcoughlin, xazax.hun.
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zdtorok set the repository for this revision to rL LLVM.
This checker should find the calls to blocking functions (for example: sleep,
getc, fgets,read,recv etc.) inside a critical section. When sleep(x) is called
while a mutex is held, other threads cannot lock the same mutex. This might
take some time, leading to bad performance or even deadlock.
Example:
```
mutex_t m;
void f() {
sleep(1000); // Error: sleep() while m is locked! [f() is called from
foobar() while m is locked]
// do some work
}
void foobar() {
lock(m);
f();
unlock(m);
}
```
Repository:
rL LLVM
http://reviews.llvm.org/D21506
Files:
include/clang/StaticAnalyzer/Checkers/Checkers.td
lib/StaticAnalyzer/Checkers/BlockInCriticalSectionChecker.cpp
lib/StaticAnalyzer/Checkers/CMakeLists.txt
test/Analysis/block-in-critical-section.cpp
Index: test/Analysis/block-in-critical-section.cpp
===================================================================
--- /dev/null
+++ test/Analysis/block-in-critical-section.cpp
@@ -0,0 +1,31 @@
+// RUN: %clang --analyze -std=c++11 -Xclang -analyzer-checker -Xclang alpha.unix.BlockInCriticalSection %s
+
+void sleep(int x) {}
+
+namespace std {
+struct mutex {
+ void lock() {}
+ void unlock() {}
+};
+}
+
+void testBlockInCriticalSection() {
+ std::mutex m;
+ m.lock();
+ sleep(3); // expected-warning {{Block in a critical section}}
+ m.unlock();
+}
+
+void testBlockInCriticalSectionWithNestedMutexes() {
+ std::mutex m, n, k;
+ m.lock();
+ n.lock();
+ k.lock();
+ sleep(3); // expected-warning {{Block in a critical section}}
+ k.unlock();
+ sleep(5); // expected-warning {{Block in a critical section}}
+ n.unlock();
+ sleep(3); // expected-warning {{Block in a critical section}}
+ m.unlock();
+ sleep(3); // no-warning
+}
Index: lib/StaticAnalyzer/Checkers/CMakeLists.txt
===================================================================
--- lib/StaticAnalyzer/Checkers/CMakeLists.txt
+++ lib/StaticAnalyzer/Checkers/CMakeLists.txt
@@ -8,6 +8,7 @@
ArrayBoundChecker.cpp
ArrayBoundCheckerV2.cpp
BasicObjCFoundationChecks.cpp
+ BlockInCriticalSectionChecker.cpp
BoolAssignmentChecker.cpp
BuiltinFunctionChecker.cpp
CStringChecker.cpp
Index: lib/StaticAnalyzer/Checkers/BlockInCriticalSectionChecker.cpp
===================================================================
--- /dev/null
+++ lib/StaticAnalyzer/Checkers/BlockInCriticalSectionChecker.cpp
@@ -0,0 +1,111 @@
+//===-- BlockInCriticalSectionChecker.cpp -----------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Defines a checker for blocks in critical sections. This checker should find
+// the calls to blocking functions (for example: sleep, getc, fgets, read,
+// recv etc.) inside a critical section. When sleep(x) is called while a mutex
+// is held, other threades cannot lock the same mutex. This might take some
+// time, leading to bad performance or even deadlock.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+
+class BlockInCriticalSectionChecker : public Checker<check::PostCall,
+ check::PreCall> {
+
+ CallDescription LockFn, UnlockFn, SleepFn, GetcFn, FgetsFn, ReadFn, RecvFn;
+
+ std::unique_ptr<BugType> BlockInCritSectionBugType;
+
+ void reportBlockInCritSection(SymbolRef FileDescSym,
+ const CallEvent &call,
+ CheckerContext &C) const;
+
+public:
+ BlockInCriticalSectionChecker();
+
+ /// Process lock.
+ /// Process blocking functions (sleep, getc, fgets, read, recv)
+ void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
+
+ /// Process unlock.
+ void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
+
+};
+
+} // end anonymous namespace
+
+REGISTER_TRAIT_WITH_PROGRAMSTATE(Counter, unsigned)
+
+BlockInCriticalSectionChecker::BlockInCriticalSectionChecker()
+ : LockFn("lock"), UnlockFn("unlock"), SleepFn("sleep"), GetcFn("getc"),
+ FgetsFn("fgets"), ReadFn("read"), RecvFn("recv") {
+ // Initialize the bug type.
+ BlockInCritSectionBugType.reset(
+ new BugType(this, "Block in critical section", "Unix Stream API Error"));
+}
+
+void BlockInCriticalSectionChecker::checkPostCall(const CallEvent &Call,
+ CheckerContext &C) const {
+ if (!Call.isCalled(LockFn)
+ && !Call.isCalled(SleepFn)
+ && !Call.isCalled(GetcFn)
+ && !Call.isCalled(FgetsFn)
+ && !Call.isCalled(ReadFn)
+ && !Call.isCalled(RecvFn))
+ return;
+
+ ProgramStateRef State = C.getState();
+ unsigned mutexCount = State->get<Counter>();
+ if (Call.isCalled(LockFn)) {
+ State = State->set<Counter>(++mutexCount);
+ C.addTransition(State);
+ } else if (mutexCount > 0) {
+ SymbolRef BlockDesc = Call.getReturnValue().getAsSymbol();
+ reportBlockInCritSection(BlockDesc, Call, C);
+ }
+}
+
+void BlockInCriticalSectionChecker::checkPreCall(const CallEvent &Call,
+ CheckerContext &C) const {
+ if (!Call.isCalled(UnlockFn))
+ return;
+
+ ProgramStateRef State = C.getState();
+ unsigned mutexCount = State->get<Counter>();
+ State = State->set<Counter>(--mutexCount);
+ C.addTransition(State);
+}
+
+void BlockInCriticalSectionChecker::reportBlockInCritSection(
+ SymbolRef BlockDescSym, const CallEvent &Call, CheckerContext &C) const {
+ ExplodedNode *ErrNode = C.generateNonFatalErrorNode();
+ if (!ErrNode)
+ return;
+
+ auto R = llvm::make_unique<BugReport>(*BlockInCritSectionBugType,
+ "Block in a critical section", ErrNode);
+ R->addRange(Call.getSourceRange());
+ R->markInteresting(BlockDescSym);
+ C.emitReport(std::move(R));
+}
+
+void ento::registerBlockInCriticalSectionChecker(CheckerManager &mgr) {
+ mgr.registerChecker<BlockInCriticalSectionChecker>();
+}
Index: include/clang/StaticAnalyzer/Checkers/Checkers.td
===================================================================
--- include/clang/StaticAnalyzer/Checkers/Checkers.td
+++ include/clang/StaticAnalyzer/Checkers/Checkers.td
@@ -402,6 +402,10 @@
HelpText<"Check for misuses of stream APIs">,
DescFile<"SimpleStreamChecker.cpp">;
+def BlockInCriticalSectionChecker : Checker<"BlockInCriticalSection">,
+ HelpText<"Check for blocks in critical section">,
+ DescFile<"BlockInCriticalSectionChecker.cpp">;
+
} // end "alpha.unix"
let ParentPackage = CString in {
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