Use error checking mutexes

Motivated by #25, which looks like a self-induced deadlock
in fellow_cache_lru_work()

src/fellow_cache.c

@@ -55,6 +55,15 @@ static char wrongbuf[1024];
 		WRONG(wrongbuf);		\
 	} while (0)
 
+pthread_mutexattr_t fc_mtxattr_errorcheck;
+static void __attribute__((constructor))
+init_mutexattr(void)
+{
+	PTOK(pthread_mutexattr_init(&fc_mtxattr_errorcheck));
+	PTOK(pthread_mutexattr_settype(&fc_mtxattr_errorcheck,
+		PTHREAD_MUTEX_ERRORCHECK));
+}
+
 struct fellow_cache_obj;
 // look up objects by fdb
 VRBT_HEAD(fellow_cache_fdb_head, fellow_cache_obj);
@@ -87,7 +96,7 @@ fellow_cache_lru_new(struct fellow_cache *fc)
 	ALLOC_OBJ(lru, FELLOW_CACHE_LRU_MAGIC);
 	AN(lru);
 	lru->fc = fc;
-	AZ(pthread_mutex_init(&lru->lru_mtx, NULL));
+	AZ(pthread_mutex_init(&lru->lru_mtx, &fc_mtxattr_errorcheck));
 	VTAILQ_INIT(&lru->lru_head);
 
 	return (lru);
@@ -749,7 +758,7 @@ fellow_cache_lrus_init(struct fellow_cache_lrus *lrus)
 {
 
 	INIT_OBJ(lrus, FELLOW_CACHE_LRUS_MAGIC);
-	AZ(pthread_mutex_init(&lrus->mtx, NULL));
+	AZ(pthread_mutex_init(&lrus->mtx, &fc_mtxattr_errorcheck));
 }
 
 static void
@@ -1953,7 +1962,7 @@ fellow_cache_obj_new(struct fellow_cache *fc,
 	fco->fco_mem = fco_mem;
 	fco->lru = fellow_cache_get_lru(fc, (uintptr_t)fco);
 
-	AZ(pthread_mutex_init(&fco->mtx, NULL));
+	AZ(pthread_mutex_init(&fco->mtx, &fc_mtxattr_errorcheck));
 	AZ(pthread_cond_init(&fco->cond, NULL));
 
 	if (fco_mem.bits) {
@@ -3463,7 +3472,7 @@ fellow_cache_async_init(struct fellow_cache *fc, fellow_task_run_t taskrun)
 	entries = fellow_io_ring_size("fellow_cache_io_entries");
 	DBG("io entries %u", entries);
 
-	AZ(pthread_mutex_init(&fc->async_mtx, NULL));
+	AZ(pthread_mutex_init(&fc->async_mtx, &fc_mtxattr_errorcheck));
 	AZ(pthread_cond_init(&fc->async_cond, NULL));
 	fc->async_ioctx = fellow_io_init(fellow_fd(fc->ffd),
 	    entries, fc->membuddy->area, fc->membuddy->map->size,
@@ -5140,7 +5149,7 @@ fellow_cache_init(struct fellow_fd *ffd, buddy_t *membuddy,
 
 	fellow_cache_lrus_init(fc->lrus);
 
-	AZ(pthread_mutex_init(&fc->fdb_mtx, NULL));
+	AZ(pthread_mutex_init(&fc->fdb_mtx, &fc_mtxattr_errorcheck));
 	VRBT_INIT(&fc->fdb_head);
 
 	fellow_cache_async_init(fc, taskrun);

src/flint.lnt

@@ -76,7 +76,7 @@
 -esym(749, *_INVAL)
 -esym(754, *_reserv*)
 // symbol not ref (constructor)
--esym(528, init_fcos_transitions, assert_fcos*)
+-esym(528, init_*, assert_fcos*)
 -esym(755, BWIT_*)
 -esym(755, fc_inj_*, FC_INJ_SZLIM_SET)	// not referenced