[cfe-dev] clang static analyzer for PthreadLockChecker.cpp

[Jean Lee]

Platform: ubuntu 12.04 i386 + clang 3.4 rc1(built by myself). Also in clang 3.3
Checker:-enable-checker alpha.unix.PthreadLock
The checker located in
llvm/tools/clang/lib/StaticAnalyzer/Checkers/PthreadLockChecker.cpp

I find the checker has false positive for "This was not the most
recently acquired lock. Possible lock order reversal".
Code is as follows:
pthread_mutex_lock(&(pNode->pIPCSocket->mutexHandle));
PushNodeMsg(pNode, pEvent); //lock + unlock other mutex
// send notify
pthread_cond_signal(&(pNode->pIPCSocket->condHandle));
pthread_mutex_unlock(&(pNode->pIPCSocket->mutexHandle));

I debug it myself with my modification listed in attached file and find
/opt/evpp/cbb/evideo/commu/ipc/trunk/src/ipc.c:502:9: warning: This
was not the most recently acquired lock. Possible lock order reversal
208741436 SymRegion{derived_$133{conj_$132{int},SymRegion{reg_$115<SymRegion{reg_$67<SymRegion{reg_$12<g_pNodeHead>}->pNext>}->pNext>}->pIPCSocket}}->mutexHandle
208753604 SymRegion{derived_$136{conj_$135{int},SymRegion{reg_$115<SymRegion{reg_$67<SymRegion{reg_$12<g_pNodeHead>}->pNext>}->pNext>}->pIPCSocket}}->mutexHandle
[0]SymRegion{derived_$133{conj_$132{int},SymRegion{reg_$115<SymRegion{reg_$67<SymRegion{reg_$12<g_pNodeHead>}->pNext>}->pNext>}->pIPCSocket}}->mutexHandle

I think maybe it is ugly to use
pthread_mutex_lock(&(pNode->pIPCSocket->mutexHandle));
...
pthread_mutex_unlock(&(pNode->pIPCSocket->mutexHandle));
and there is no false positive if I modify to
pthread_mutex_lock(&(pIPCSocket->mutexHandle));
...
pthread_mutex_unlock(&(pIPCSocket->mutexHandle));

So, I guess the code(PthreadLockChecker.cpp)
const MemRegion *firstLockR = LS.getHead();
  if (firstLockR != lockR) {
    //This was not the most recently acquired lock. Possible lock order reversal
  }
is insuffient.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: PthreadLockChecker.cpp
Type: text/x-c++src
Size: 7830 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20131123/963f0491/attachment.cpp>