After cancelling a thread (unless it's detached, but mining threads aren't), it is always necessary to join the thread so the system will release resources.

This also simplifies kill_mining a bit.

driver-opencl.c

@@ -1061,9 +1061,9 @@ select_cgpu:
     thr->rolling = thr->cgpu->rolling = 0;
     /* Reports the last time we tried to revive a sick GPU */
     cgtime(&thr->sick);
-    if (!pthread_cancel(thr->pth)) {
+    if (!pthread_kill(thr->pth, 0)) {
       applog(LOG_WARNING, "Thread %d still exists, killing it off", thr_id);
-      pthread_join(thr->pth, NULL);
+      cg_completion_timeout(&thr_info_cancel_join, thr, 5000);
       thr->cgpu->drv->thread_shutdown(thr);
     } else
       applog(LOG_WARNING, "Thread %d no longer exists", thr_id);

sgminer.c

@@ -3310,7 +3310,7 @@ static void disable_curses(void)
 
 static void kill_timeout(struct thr_info *thr)
 {
-  cg_completion_timeout(&thr_info_cancel, thr, 1000);
+  cg_completion_timeout(&thr_info_cancel_join, thr, 1000);
 }
 
 static void kill_mining(void)
@@ -3322,21 +3322,9 @@ static void kill_mining(void)
   /* Kill the mining threads*/
   rd_lock(&mining_thr_lock);
   for (i = 0; i < mining_threads; i++) {
-    pthread_t *pth = (pthread_t *) calloc(1, sizeof(pthread_t));
-
     thr = mining_thr[i];
-    if (thr && PTH(thr) != 0L)
-      *pth = thr->pth;
-    thr_info_cancel(thr);
     forcelog(LOG_DEBUG, "Waiting for thread %d to finish...", thr->id);
-#ifndef WIN32
-    if (pth && *pth)
-      pthread_join(*pth, NULL);
-#else
-    if (pth && pth->p)
-      pthread_join(*pth, NULL);
-#endif
-    free(pth);
+    thr_info_cancel_join(thr);
   }
   rd_unlock(&mining_thr_lock);
 }

util.c

@@ -825,13 +825,14 @@ int thr_info_create(struct thr_info *thr, pthread_attr_t *attr, void *(*start) (
   return pthread_create(&thr->pth, attr, start, arg);
 }
 
-void thr_info_cancel(struct thr_info *thr)
+void thr_info_cancel_join(struct thr_info *thr)
 {
   if (!thr)
     return;
 
   if (PTH(thr) != 0L) {
     pthread_cancel(thr->pth);
+    pthread_join(thr->pth, NULL);
     PTH(thr) = 0L;
   }
   cgsem_destroy(&thr->sem);

util.h

@@ -107,7 +107,7 @@ struct pool;
 enum dev_reason;
 struct cgpu_info;
 int thr_info_create(struct thr_info *thr, pthread_attr_t *attr, void *(*start) (void *), void *arg);
-void thr_info_cancel(struct thr_info *thr);
+void thr_info_cancel_join(struct thr_info *thr);
 void cgtime(struct timeval *tv);
 void subtime(struct timeval *a, struct timeval *b);
 void addtime(struct timeval *a, struct timeval *b);