contrib/llvm/tools/clang/lib/StaticAnalyzer/Checkers/BlockInCriticalSectionChecker.cpp

   1 //===-- BlockInCriticalSectionChecker.cpp -----------------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Defines a checker for blocks in critical sections. This checker should find
  11 // the calls to blocking functions (for example: sleep, getc, fgets, read,
  12 // recv etc.) inside a critical section. When sleep(x) is called while a mutex
  13 // is held, other threades cannot lock the same mutex. This might take some
  14 // time, leading to bad performance or even deadlock.
  15 //
  16 //===----------------------------------------------------------------------===//
  17
  18 #include "ClangSACheckers.h"
  19 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
  20 #include "clang/StaticAnalyzer/Core/Checker.h"
  21 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
  22 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
  23
  24 using namespace clang;
  25 using namespace ento;
  26
  27 namespace {
  28
  29 class BlockInCriticalSectionChecker : public Checker<check::PostCall,
  30                                                      check::PreCall> {
  31
  32   CallDescription LockFn, UnlockFn, SleepFn, GetcFn, FgetsFn, ReadFn, RecvFn,
  33                   PthreadLockFn, PthreadTryLockFn, PthreadUnlockFn,
  34                   MtxLock, MtxTimedLock, MtxTryLock, MtxUnlock;
  35
  36   std::unique_ptr<BugType> BlockInCritSectionBugType;
  37
  38   void reportBlockInCritSection(SymbolRef FileDescSym,
  39                                 const CallEvent &call,
  40                                 CheckerContext &C) const;
  41
  42 public:
  43   BlockInCriticalSectionChecker();
  44
  45   bool isBlockingFunction(const CallEvent &Call) const;
  46   bool isLockFunction(const CallEvent &Call) const;
  47   bool isUnlockFunction(const CallEvent &Call) const;
  48
  49   void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
  50
  51   /// Process unlock.
  52   /// Process lock.
  53   /// Process blocking functions (sleep, getc, fgets, read, recv)
  54   void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
  55
  56 };
  57
  58 } // end anonymous namespace
  59
  60 REGISTER_TRAIT_WITH_PROGRAMSTATE(MutexCounter, unsigned)
  61
  62 BlockInCriticalSectionChecker::BlockInCriticalSectionChecker()
  63     : LockFn("lock"), UnlockFn("unlock"), SleepFn("sleep"), GetcFn("getc"),
  64       FgetsFn("fgets"), ReadFn("read"), RecvFn("recv"),
  65       PthreadLockFn("pthread_mutex_lock"),
  66       PthreadTryLockFn("pthread_mutex_trylock"),
  67       PthreadUnlockFn("pthread_mutex_unlock"),
  68       MtxLock("mtx_lock"),
  69       MtxTimedLock("mtx_timedlock"),
  70       MtxTryLock("mtx_trylock"),
  71       MtxUnlock("mtx_unlock") {
  72   // Initialize the bug type.
  73   BlockInCritSectionBugType.reset(
  74       new BugType(this, "Call to blocking function in critical section",
  75                         "Blocking Error"));
  76 }
  77
  78 bool BlockInCriticalSectionChecker::isBlockingFunction(const CallEvent &Call) const {
  79   if (Call.isCalled(SleepFn)
  80       || Call.isCalled(GetcFn)
  81       || Call.isCalled(FgetsFn)
  82       || Call.isCalled(ReadFn)
  83       || Call.isCalled(RecvFn)) {
  84     return true;
  85   }
  86   return false;
  87 }
  88
  89 bool BlockInCriticalSectionChecker::isLockFunction(const CallEvent &Call) const {
  90   if (Call.isCalled(LockFn)
  91       || Call.isCalled(PthreadLockFn)
  92       || Call.isCalled(PthreadTryLockFn)
  93       || Call.isCalled(MtxLock)
  94       || Call.isCalled(MtxTimedLock)
  95       || Call.isCalled(MtxTryLock)) {
  96     return true;
  97   }
  98   return false;
  99 }
 100
 101 bool BlockInCriticalSectionChecker::isUnlockFunction(const CallEvent &Call) const {
 102   if (Call.isCalled(UnlockFn)
 103        || Call.isCalled(PthreadUnlockFn)
 104        || Call.isCalled(MtxUnlock)) {
 105     return true;
 106   }
 107   return false;
 108 }
 109
 110 void BlockInCriticalSectionChecker::checkPreCall(const CallEvent &Call,
 111                                                  CheckerContext &C) const {
 112 }
 113
 114 void BlockInCriticalSectionChecker::checkPostCall(const CallEvent &Call,
 115                                                   CheckerContext &C) const {
 116   if (!isBlockingFunction(Call)
 117       && !isLockFunction(Call)
 118       && !isUnlockFunction(Call))
 119     return;
 120
 121   ProgramStateRef State = C.getState();
 122   unsigned mutexCount = State->get<MutexCounter>();
 123   if (isUnlockFunction(Call) && mutexCount > 0) {
 124     State = State->set<MutexCounter>(--mutexCount);
 125     C.addTransition(State);
 126   } else if (isLockFunction(Call)) {
 127     State = State->set<MutexCounter>(++mutexCount);
 128     C.addTransition(State);
 129   } else if (mutexCount > 0) {
 130     SymbolRef BlockDesc = Call.getReturnValue().getAsSymbol();
 131     reportBlockInCritSection(BlockDesc, Call, C);
 132   }
 133 }
 134
 135 void BlockInCriticalSectionChecker::reportBlockInCritSection(
 136     SymbolRef BlockDescSym, const CallEvent &Call, CheckerContext &C) const {
 137   ExplodedNode *ErrNode = C.generateNonFatalErrorNode();
 138   if (!ErrNode)
 139     return;
 140
 141   std::string msg;
 142   llvm::raw_string_ostream os(msg);
 143   os << "Call to blocking function '" << Call.getCalleeIdentifier()->getName()
 144      << "' inside of critical section";
 145   auto R = llvm::make_unique<BugReport>(*BlockInCritSectionBugType, os.str(), ErrNode);
 146   R->addRange(Call.getSourceRange());
 147   R->markInteresting(BlockDescSym);
 148   C.emitReport(std::move(R));
 149 }
 150
 151 void ento::registerBlockInCriticalSectionChecker(CheckerManager &mgr) {
 152   mgr.registerChecker<BlockInCriticalSectionChecker>();
 153 }