bugfix: potential abort with DA queue after high watermark is reached

There exists a race condition that can lead to a segfault. Thanks
go to vbernetr, who performed the analysis and provided patch, which
I only tweaked a very little bit.

1 files changed, 69 insertions, 0 deletions

diff --git a/runtime/debug.c b/runtime/debug.c
index 1450d029..9d45c737 100644
--- a/runtime/debug.c
+++ b/runtime/debug.c
@@ -473,6 +473,55 @@ static inline void dbgMutexLockLog(pthread_mutex_t *pmut, dbgFuncDB_t *pFuncDB,
 		dbgprintf("%s:%d:%s: mutex %p aquired\n", pFuncDB->file, lockLn, pFuncDB->func, (void*)pmut); 
 }
 
+
+/* report trylock on a mutex and add it to the mutex log */
+static inline void dbgMutexPreTryLockLog(pthread_mutex_t *pmut, dbgFuncDB_t *pFuncDB, int ln)
+{
+   dbgMutLog_t *pHolder;
+   dbgMutLog_t *pLog;
+   char pszBuf[128];
+   char pszHolderThrdName[64];
+   char *pszHolder;
+
+   pthread_mutex_lock(&mutMutLog);
+   pHolder = dbgMutLogFindHolder(pmut);
+   pLog = dbgMutLogAddEntry(pmut, MUTOP_TRYLOCK, pFuncDB, ln);
+
+   if(pHolder == NULL)
+      pszHolder = "[NONE]";
+   else {
+      dbgGetThrdName(pszHolderThrdName, sizeof(pszHolderThrdName), pHolder->thrd, 1);
+      snprintf(pszBuf, sizeof(pszBuf)/sizeof(char), "%s:%d [%s]", pHolder->pFuncDB->file, pHolder->lockLn, pszHolderThrdName);
+      pszHolder = pszBuf;
+   }
+
+   if(bPrintMutexAction)
+      dbgprintf("%s:%d:%s: mutex %p trying to get lock, held by %s\n", pFuncDB->file, ln, pFuncDB->func, (void*)pmut, pszHolder);
+   pthread_mutex_unlock(&mutMutLog);
+}
+
+
+/* report attempted mutex lock */
+static inline void dbgMutexTryLockLog(pthread_mutex_t *pmut, dbgFuncDB_t *pFuncDB, int lockLn)
+{
+   dbgMutLog_t *pLog;
+
+   pthread_mutex_lock(&mutMutLog);
+
+   /* find and delete "trylock" entry */
+   pLog = dbgMutLogFindSpecific(pmut, MUTOP_TRYLOCK, pFuncDB);
+   assert(pLog != NULL);
+   dbgMutLogDelEntry(pLog);
+
+   /* add "lock" entry */
+   pLog = dbgMutLogAddEntry(pmut, MUTOP_LOCK, pFuncDB, lockLn);
+   dbgFuncDBAddMutexLock(pFuncDB, pmut, lockLn);
+   pthread_mutex_unlock(&mutMutLog);
+   if(bPrintMutexAction)
+      dbgprintf("%s:%d:%s: mutex %p aquired\n", pFuncDB->file, lockLn, pFuncDB->func, (void*)pmut);
+}
+
+
 /* if we unlock, we just remove the lock aquired entry from the log list */
 static inline void dbgMutexUnlockLog(pthread_mutex_t *pmut, dbgFuncDB_t *pFuncDB, int unlockLn)
 {
@@ -515,6 +564,26 @@ int dbgMutexLock(pthread_mutex_t *pmut, dbgFuncDB_t *pFuncDB, int ln, int iStack
 }
 
 
+/* wrapper for pthread_mutex_trylock() */
+int dbgMutexTryLock(pthread_mutex_t *pmut, dbgFuncDB_t *pFuncDB, int ln, int iStackPtr)
+{
+   int ret;
+
+   dbgRecordExecLocation(iStackPtr, ln);
+   dbgMutexPreLockLog(pmut, pFuncDB, ln); // TODO : update this
+   ret = pthread_mutex_trylock(pmut);
+   if(ret == 0 || ret == EBUSY) {
+      // TODO : update this
+      dbgMutexLockLog(pmut, pFuncDB, ln);
+   } else {
+      dbgprintf("%s:%d:%s: ERROR: pthread_mutex_trylock() for mutex %p failed with error %d\n",
+           pFuncDB->file, ln, pFuncDB->func, (void*)pmut, ret);
+   }
+
+   return ret;
+}
+
+
 /* wrapper for pthread_mutex_unlock() */
 int dbgMutexUnlock(pthread_mutex_t *pmut, dbgFuncDB_t *pFuncDB, int ln, int iStackPtr)
 {