From: adash <adash>
Date: Thu, 7 May 2009 19:26:22 +0000 (+0000)
Subject: race condition fixed: race due to thread rec becoming NULL before accessing its field... 
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=e1026930b587bd6dd313190f857d08547158809e;p=IRC.git

race condition fixed: race due to thread rec becoming NULL before accessing its field/element
---

diff --git a/Robust/src/Runtime/STM/stm.c b/Robust/src/Runtime/STM/stm.c
index 71bb1214..c731895b 100644
--- a/Robust/src/Runtime/STM/stm.c
+++ b/Robust/src/Runtime/STM/stm.c
@@ -12,6 +12,8 @@
 
 #include "tm.h"
 #include "garbage.h"
+
+/*** Globals *****/
 /* Thread transaction variables */
 __thread objstr_t *t_cache;
 __thread objstr_t *t_reserve;
@@ -27,8 +29,9 @@ int nSoftAbortAbort = 0;
 
 #ifdef STMSTATS
 /* Thread variable for locking/unlocking */
-__thread threadrec_t trec;
+__thread threadrec_t *trec;
 __thread struct objlist * lockedobjs;
+/** Global lock **/
 int typesCausingAbort[TOTALNUMCLASSANDARRAY];
 /******Keep track of objects and types causing aborts******/
 /*TODO
@@ -787,8 +790,36 @@ void getTotalAbortCount(int start, int stop, void *startptr, void *checkptr, cha
  * Locks an object that causes aborts
  **/
 void needLock(objheader_t *header) {
+  int lockstatus;
+  threadrec_t *ptr;
+  while((lockstatus = pthread_mutex_trylock(&(header->objlock))) 
+      && ((ptr = header->trec) == NULL)) { //retry
+    ;
+  }
+  if(!lockstatus) { //acquired lock
+    //TODO printf("%s() Got lock on type= %d in first try\n", __func__, TYPE(header));
+    /* Reset blocked field */
+    trec->blocked = 0;
+    /* Set trec */
+    header->trec = trec;
+  } else { //failed to get lock
+    if(ptr->blocked == 1) { //ignore locking
+      return;
+    } else { //lock that blocks
+      pthread_mutex_lock(&(header->objlock));
+      //TODO printf("%s() Got lock on type= %d in second try\n", __func__, TYPE(header));
+      /* Reset blocked field */
+      trec->blocked = 0;
+      /* Set trec */
+      header->trec = trec;
+    }
+  }
+
+
+#if 0
   if(pthread_mutex_trylock(&(header->objlock))) { //busy and failed to get locked
-    trec.blocked = 1; //set blocked flag
+    trec->blocked = 1; //set blocked flag
+    while(
     while(header->trec == NULL) { //retry
       ;
     }
@@ -798,17 +829,18 @@ void needLock(objheader_t *header) {
       pthread_mutex_lock(&(header->objlock));
       //TODO printf("%s() Got lock on type= %d in second try\n", __func__, TYPE(header));
       /* Reset blocked field */
-      trec.blocked = 0;
+      trec->blocked = 0;
       /* Set trec */
-      header->trec = &trec;
+      header->trec = trec;
     }
   } else { //acquired lock
     //TODO printf("%s() Got lock on type= %d in first try\n", __func__, TYPE(header));
     /* Reset blocked field */
-    trec.blocked = 0;
+    trec->blocked = 0;
     /* Set trec */
-    header->trec = &trec;
+    header->trec = trec;
   }
+#endif
   /* Save the locked object */
   if (lockedobjs->offset<MAXOBJLIST) {
     lockedobjs->objs[lockedobjs->offset++]=OID(header);
diff --git a/Robust/src/Runtime/STM/tm.h b/Robust/src/Runtime/STM/tm.h
index a1668206..2c98fc6a 100644
--- a/Robust/src/Runtime/STM/tm.h
+++ b/Robust/src/Runtime/STM/tm.h
@@ -20,7 +20,6 @@
 #include <pthread.h>
 #include <sys/time.h>
 #include <errno.h>
-//#include "threadnotify.h"
 #include "stmlookup.h"
 #include "dsmlock.h"
 
@@ -126,7 +125,7 @@ extern __thread struct objlist * newobjs;
 extern __thread objstr_t *t_cache;
 extern __thread objstr_t *t_reserve;
 #ifdef STMSTATS
-extern __thread threadrec_t trec;
+extern __thread threadrec_t *trec;
 extern __thread struct objlist * lockedobjs;
 #endif
 
diff --git a/Robust/src/Runtime/thread.c b/Robust/src/Runtime/thread.c
index 3f3a5898..18bb2281 100644
--- a/Robust/src/Runtime/thread.c
+++ b/Robust/src/Runtime/thread.c
@@ -115,7 +115,8 @@ void initializethreads() {
   t_reserve=NULL;
   t_chashCreate(CHASH_SIZE, CLOADFACTOR);
 #ifdef STMSTATS
-  trec.blocked = 0;
+  trec=calloc(1, sizeof(threadrec_t));
+  trec->blocked = 0;
   lockedobjs=calloc(1, sizeof(struct objlist));
 #endif
 #endif
@@ -130,7 +131,8 @@ void initthread(struct ___Thread___ * ___this___) {
 #else
   newobjs=calloc(1, sizeof(struct objlist));
 #ifdef STMSTATS
-  trec.blocked = 0;
+  trec=calloc(1, sizeof(threadrec_t));
+  trec->blocked = 0;
   lockedobjs=calloc(1, sizeof(struct objlist));
 #endif
   t_cache = objstrCreate(1048576);