Merge branch 'sverker/lock-check-matrix'

11 files changed, 646 insertions, 369 deletions

diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index d443e12409..89e3d3f43e 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -4055,6 +4055,15 @@ BIF_RETTYPE erts_debug_get_internal_state_1(BIF_ALIST_1)
             BIF_RET(am_false);
 #endif
         }
+        else if (ERTS_IS_ATOM_STR("lc_graph", BIF_ARG_1)) {
+#ifdef ERTS_ENABLE_LOCK_CHECK
+            Eterm res = erts_lc_dump_graph();
+            BIF_RET(res);
+#else
+            BIF_RET(am_notsup);
+#endif
+        }
+
     }
     else if (is_tuple(BIF_ARG_1)) {
 	Eterm* tp = tuple_val(BIF_ARG_1);
diff --git a/erts/emulator/beam/erl_lock_check.c b/erts/emulator/beam/erl_lock_check.c
index 0ced5ec310..d66410367b 100644
--- a/erts/emulator/beam/erl_lock_check.c
+++ b/erts/emulator/beam/erl_lock_check.c
@@ -41,6 +41,7 @@
 #include "erl_lock_check.h"
 #include "erl_term.h"
 #include "erl_threads.h"
+#include "erl_atom_table.h"
 
 typedef struct {
     char *name;
@@ -75,10 +76,10 @@ static erts_lc_lock_order_t erts_lock_order[] = {
      *						 if only one lock use
      *						 the lock name)"
      */
+    {   "NO LOCK",                              NULL                    },
     {	"driver_lock",				"driver_name"		},
     {	"port_lock",				"port_id"		},
     {	"port_data_lock",			"address"		},
-    {	"bif_timers",				NULL			},
     {	"reg_tab",				NULL			},
     {	"proc_main",				"pid"			},
     {   "old_code",                             "address"               },
@@ -103,7 +104,6 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {	"node_table",				NULL			},
     {	"dist_table",				NULL			},
     {	"sys_tracers",				NULL			},
-    {	"module_tab",				NULL			},
     {	"export_tab",				NULL			},
     {	"fun_tab",				NULL			},
     {	"environ",				NULL			},
@@ -111,7 +111,6 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {	"drv_ev_state_grow",			NULL,   		},
     {	"drv_ev_state",				"address"		},
     {	"safe_hash",				"address"		},
-    {   "removed_fd_pre_alloc_lock",            "address"               },
     {   "state_prealloc",                       NULL                    },
     {	"schdlr_sspnd",				NULL			},
     {	"migration_info_update",		NULL			},
@@ -134,10 +133,6 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {   "msacc_list_mutex",                     NULL                    },
     {   "msacc_unmanaged_mutex",                NULL                    },
     {	"atom_tab",				NULL			},
-    {	"misc_op_list_pre_alloc_lock",		"address"		},
-    {	"message_pre_alloc_lock",		"address"		},
-    {	"ptimer_pre_alloc_lock",		"address",		},
-    {	"btm_pre_alloc_lock",			NULL,			},
     {	"dist_entry_out_queue",			"address"		},
     {	"port_sched_lock",			"port_id"		},
     {	"sys_msg_q", 				NULL			},
@@ -147,20 +142,12 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {	"mtrace_op",				NULL			},
     {	"instr_x",				NULL			},
     {	"instr",				NULL			},
-    {	"pollsets_lock",			NULL			},
     {	"alcu_allocator",			"index"			},
     {	"mseg",					NULL			},
-    {	"port_task_pre_alloc_lock",		"address"		},
-    {	"proclist_pre_alloc_lock",		"address"		},
-    {	"xports_list_pre_alloc_lock",		"address"		},
-    {	"inet_buffer_stack_lock",		NULL			},
-    {	"system_block",				NULL			},
     {	"get_time",				NULL			},
     {	"get_corrected_time",			NULL			},
     {	"runtime",				NULL			},
-    {	"breakpoints",				NULL			},
     {	"pix_lock",				"address"		},
-    {	"run_queues_lists",			NULL			},
     {	"sched_stat",				NULL			},
     {	"async_init_mtx",			NULL			},
 #ifdef __WIN32__
@@ -194,10 +181,10 @@ static const char *rw_op_str(erts_lock_options_t options)
     return erts_lock_options_get_short_desc(options);
 }
 
-typedef struct erts_lc_locked_lock_t_ erts_lc_locked_lock_t;
-struct erts_lc_locked_lock_t_ {
-    erts_lc_locked_lock_t *next;
-    erts_lc_locked_lock_t *prev;
+typedef struct lc_locked_lock_t_ lc_locked_lock_t;
+struct lc_locked_lock_t_ {
+    lc_locked_lock_t *next;
+    lc_locked_lock_t *prev;
     UWord extra;
     Sint16 id;
     char *file;
@@ -207,32 +194,47 @@ struct erts_lc_locked_lock_t_ {
 };
 
 typedef struct {
-    erts_lc_locked_lock_t *first;
-    erts_lc_locked_lock_t *last;
-} erts_lc_locked_lock_list_t;
+    lc_locked_lock_t *first;
+    lc_locked_lock_t *last;
+} lc_locked_lock_list_t;
+
+typedef union lc_free_block_t_ lc_free_block_t;
+union lc_free_block_t_ {
+    lc_free_block_t *next;
+    lc_locked_lock_t lock;
+};
+
+typedef struct {
+    /*
+     * m[X][Y] & 1 if we locked X directly after Y was locked.
+     * m[X][Y] & 2 if we locked X indirectly after Y was locked.
+     * m[X][0] = 1 if we locked X when nothing else was locked.
+     * m[0][] is unused as it would represent locking "NO LOCK"
+     */
+    char m[ERTS_LOCK_ORDER_SIZE][ERTS_LOCK_ORDER_SIZE];
+
+} lc_matrix_t;
 
-typedef struct erts_lc_locked_locks_t_ erts_lc_locked_locks_t;
-struct erts_lc_locked_locks_t_ {
+static lc_matrix_t tot_lc_matrix;
+
+typedef struct lc_thread_t_ lc_thread_t;
+struct lc_thread_t_ {
     char *thread_name;
     int emu_thread;
     erts_tid_t tid;
-    erts_lc_locked_locks_t *next;
-    erts_lc_locked_locks_t *prev;
-    erts_lc_locked_lock_list_t locked;
-    erts_lc_locked_lock_list_t required;
-};
-
-typedef union erts_lc_free_block_t_ erts_lc_free_block_t;
-union erts_lc_free_block_t_ {
-    erts_lc_free_block_t *next;
-    erts_lc_locked_lock_t lock;
+    lc_thread_t *next;
+    lc_thread_t *prev;
+    lc_locked_lock_list_t locked;
+    lc_locked_lock_list_t required;
+    lc_free_block_t *free_blocks;
+    lc_matrix_t matrix;
 };
 
 static ethr_tsd_key locks_key;
 
-static erts_lc_locked_locks_t *erts_locked_locks = NULL;
+static lc_thread_t *lc_threads = NULL;
+static ethr_spinlock_t lc_threads_lock;
 
-static erts_lc_free_block_t *free_blocks = NULL;
 
 #ifdef ERTS_LC_STATIC_ALLOC
 #define ERTS_LC_FB_CHUNK_SIZE 10000
@@ -240,176 +242,165 @@ static erts_lc_free_block_t *free_blocks = NULL;
 #define ERTS_LC_FB_CHUNK_SIZE 10
 #endif
 
-static ethr_spinlock_t free_blocks_lock;
 
 static ERTS_INLINE void
-lc_lock(void)
+lc_lock_threads(void)
 {
-    ethr_spin_lock(&free_blocks_lock);
+    ethr_spin_lock(&lc_threads_lock);
 }
 
 static ERTS_INLINE void
-lc_unlock(void)
+lc_unlock_threads(void)
 {
-    ethr_spin_unlock(&free_blocks_lock);
+    ethr_spin_unlock(&lc_threads_lock);
 }
 
-static ERTS_INLINE void lc_free(void *p)
+static ERTS_INLINE void lc_free(lc_thread_t* thr, lc_locked_lock_t *p)
 {
-    erts_lc_free_block_t *fb = (erts_lc_free_block_t *) p;
+    lc_free_block_t *fb = (lc_free_block_t *) p;
 #ifdef DEBUG
-    sys_memset((void *) p, 0xdf, sizeof(erts_lc_free_block_t));
+    sys_memset((void *) p, 0xdf, sizeof(lc_free_block_t));
 #endif
-    lc_lock();
-    fb->next = free_blocks;
-    free_blocks = fb;
-    lc_unlock();   
+    fb->next = thr->free_blocks;
+    thr->free_blocks = fb;
 }
 
-#ifdef ERTS_LC_STATIC_ALLOC
-
-static void *lc_core_alloc(void)
-{
-    lc_unlock();
-    ERTS_INTERNAL_ERROR("Lock checker out of memory!\n");
-}
-
-#else
-
-static void *lc_core_alloc(void)
+static lc_locked_lock_t *lc_core_alloc(lc_thread_t* thr)
 {
     int i;
-    erts_lc_free_block_t *fbs;
-    lc_unlock();
-    fbs = (erts_lc_free_block_t *) malloc(sizeof(erts_lc_free_block_t)
+    lc_free_block_t *fbs;
+    fbs = (lc_free_block_t *) malloc(sizeof(lc_free_block_t)
 					  * ERTS_LC_FB_CHUNK_SIZE);
     if (!fbs) {
         ERTS_INTERNAL_ERROR("Lock checker failed to allocate memory!");
     }
     for (i = 1; i < ERTS_LC_FB_CHUNK_SIZE - 1; i++) {
 #ifdef DEBUG
-	sys_memset((void *) &fbs[i], 0xdf, sizeof(erts_lc_free_block_t));
+	sys_memset((void *) &fbs[i], 0xdf, sizeof(lc_free_block_t));
 #endif
 	fbs[i].next = &fbs[i+1];
     }
 #ifdef DEBUG
     sys_memset((void *) &fbs[ERTS_LC_FB_CHUNK_SIZE-1],
-	   0xdf, sizeof(erts_lc_free_block_t));
+	   0xdf, sizeof(lc_free_block_t));
 #endif
-    lc_lock();
-    fbs[ERTS_LC_FB_CHUNK_SIZE-1].next = free_blocks;
-    free_blocks = &fbs[1];
-    return (void *) &fbs[0];
+    fbs[ERTS_LC_FB_CHUNK_SIZE-1].next = thr->free_blocks;
+    thr->free_blocks = &fbs[1];
+    return &fbs[0].lock;
 }
 
-#endif
-
-static ERTS_INLINE void *lc_alloc(void)
+static ERTS_INLINE lc_locked_lock_t *lc_alloc(lc_thread_t* thr)
 {
-    void *res;
-    lc_lock();
-    if (!free_blocks)
-	res = lc_core_alloc();
+    lc_locked_lock_t *res;
+    if (!thr->free_blocks)
+	res = lc_core_alloc(thr);
     else {
-	res = (void *) free_blocks;
-	free_blocks = free_blocks->next;
+	res = &thr->free_blocks->lock;
+	thr->free_blocks = thr->free_blocks->next;
     }
-    lc_unlock();
     return res;
 }
 
 
-static erts_lc_locked_locks_t *
-create_locked_locks(char *thread_name)
+static lc_thread_t *
+create_thread_data(char *thread_name)
 {
-    erts_lc_locked_locks_t *l_lcks = malloc(sizeof(erts_lc_locked_locks_t));
-    if (!l_lcks)
+    lc_thread_t *thr = malloc(sizeof(lc_thread_t));
+    if (!thr)
 	ERTS_INTERNAL_ERROR("Lock checker failed to allocate memory!");
 
-    l_lcks->thread_name = strdup(thread_name ? thread_name : "unknown");
-    if (!l_lcks->thread_name)
+    thr->thread_name = strdup(thread_name ? thread_name : "unknown");
+    if (!thr->thread_name)
 	ERTS_INTERNAL_ERROR("Lock checker failed to allocate memory!");
 
-    l_lcks->emu_thread = 0;
-    l_lcks->tid = erts_thr_self();
-    l_lcks->required.first = NULL;
-    l_lcks->required.last = NULL;
-    l_lcks->locked.first = NULL;
-    l_lcks->locked.last = NULL;
-    l_lcks->prev = NULL;
-    lc_lock();
-    l_lcks->next = erts_locked_locks;
-    if (erts_locked_locks)
-	erts_locked_locks->prev = l_lcks;
-    erts_locked_locks = l_lcks;
-    lc_unlock();
-    erts_tsd_set(locks_key, (void *) l_lcks);
-    return l_lcks;
+    thr->emu_thread = 0;
+    thr->tid = erts_thr_self();
+    thr->required.first = NULL;
+    thr->required.last = NULL;
+    thr->locked.first = NULL;
+    thr->locked.last = NULL;
+    thr->prev = NULL;
+    thr->free_blocks = NULL;
+    sys_memzero(&thr->matrix, sizeof(thr->matrix));
+
+    lc_lock_threads();
+    thr->next = lc_threads;
+    if (lc_threads)
+	lc_threads->prev = thr;
+    lc_threads = thr;
+    lc_unlock_threads();
+    erts_tsd_set(locks_key, (void *) thr);
+    return thr;
 }
 
+static void collect_matrix(lc_matrix_t*);
+
 static void
-destroy_locked_locks(erts_lc_locked_locks_t *l_lcks)
-{
-    ASSERT(l_lcks->thread_name);
-    free((void *) l_lcks->thread_name);
-    ASSERT(l_lcks->required.first == NULL);
-    ASSERT(l_lcks->required.last == NULL);
-    ASSERT(l_lcks->locked.first == NULL);
-    ASSERT(l_lcks->locked.last == NULL);
-
-    lc_lock();
-    if (l_lcks->prev)
-	l_lcks->prev->next = l_lcks->next;
+destroy_locked_locks(lc_thread_t *thr)
+{
+    ASSERT(thr->thread_name);
+    free((void *) thr->thread_name);
+    ASSERT(thr->required.first == NULL);
+    ASSERT(thr->required.last == NULL);
+    ASSERT(thr->locked.first == NULL);
+    ASSERT(thr->locked.last == NULL);
+
+    lc_lock_threads();
+    if (thr->prev)
+	thr->prev->next = thr->next;
     else {
-	ASSERT(erts_locked_locks == l_lcks);
-	erts_locked_locks = l_lcks->next;
+	ASSERT(lc_threads == thr);
+	lc_threads = thr->next;
     }
+    if (thr->next)
+	thr->next->prev = thr->prev;
+
+    collect_matrix(&thr->matrix);
 
-    if (l_lcks->next)
-	l_lcks->next->prev = l_lcks->prev;
-    lc_unlock();
+    lc_unlock_threads();
 
-    free((void *) l_lcks);
+    free((void *) thr);
 
 }
 
-static ERTS_INLINE erts_lc_locked_locks_t *
+static ERTS_INLINE lc_thread_t *
 get_my_locked_locks(void)
 {
     return erts_tsd_get(locks_key);
 }
 
-static ERTS_INLINE erts_lc_locked_locks_t *
+static ERTS_INLINE lc_thread_t *
 make_my_locked_locks(void)
 {
-    erts_lc_locked_locks_t *l_lcks = get_my_locked_locks();
-    if (l_lcks)
-	return l_lcks;
+    lc_thread_t *thr = get_my_locked_locks();
+    if (thr)
+	return thr;
     else
-	return create_locked_locks(NULL);
+	return create_thread_data(NULL);
 }
 
-static ERTS_INLINE erts_lc_locked_lock_t *
-new_locked_lock(erts_lc_lock_t *lck, erts_lock_options_t options,
+static ERTS_INLINE lc_locked_lock_t *
+new_locked_lock(lc_thread_t* thr,
+                erts_lc_lock_t *lck, erts_lock_options_t options,
 		char *file, unsigned int line)
 {
-    erts_lc_locked_lock_t *l_lck = (erts_lc_locked_lock_t *) lc_alloc();
-    l_lck->next = NULL;
-    l_lck->prev = NULL;
-    l_lck->id = lck->id;
-    l_lck->extra = lck->extra;
-    l_lck->file = file;
-    l_lck->line = line;
-    l_lck->flags = lck->flags;
-    l_lck->taken_options = options;
-    return l_lck;
+    lc_locked_lock_t *ll = lc_alloc(thr);
+    ll->next = NULL;
+    ll->prev = NULL;
+    ll->id = lck->id;
+    ll->extra = lck->extra;
+    ll->file = file;
+    ll->line = line;
+    ll->flags = lck->flags;
+    ll->taken_options = options;
+    return ll;
 }
 
 static void
 raw_print_lock(char *prefix, Sint16 id, Wterm extra, erts_lock_flags_t flags,
 	       char* file, unsigned int line, char *suffix)
 {
-    char *lname = (0 <= id && id < ERTS_LOCK_ORDER_SIZE
+    char *lname = (1 <= id && id < ERTS_LOCK_ORDER_SIZE
 		   ? erts_lock_order[id].name
 		   : "unknown");
     erts_fprintf(stderr,"%s'%s:",prefix,lname);
@@ -439,20 +430,20 @@ print_lock(char *prefix, erts_lc_lock_t *lck, char *suffix)
 }
 
 static void
-print_curr_locks(erts_lc_locked_locks_t *l_lcks)
+print_curr_locks(lc_thread_t *thr)
 {
-    erts_lc_locked_lock_t *l_lck;
-    if (!l_lcks || !l_lcks->locked.first)
+    lc_locked_lock_t *ll;
+    if (!thr || !thr->locked.first)
 	erts_fprintf(stderr,
 		     "Currently no locks are locked by the %s thread.\n",
-		     l_lcks->thread_name);
+		     thr->thread_name);
     else {
 	erts_fprintf(stderr,
 		     "Currently these locks are locked by the %s thread:\n",
-		     l_lcks->thread_name);
-	for (l_lck = l_lcks->locked.first; l_lck; l_lck = l_lck->next)
-	  raw_print_lock("  ", l_lck->id, l_lck->extra, l_lck->flags,
-			 l_lck->file, l_lck->line, "\n");
+		     thr->thread_name);
+	for (ll = thr->locked.first; ll; ll = ll->next)
+	  raw_print_lock("  ", ll->id, ll->extra, ll->flags,
+			 ll->file, ll->line, "\n");
     }
 }
 
@@ -481,55 +472,55 @@ uninitialized_lock(void)
 }
 
 static void
-lock_twice(char *prefix, erts_lc_locked_locks_t *l_lcks, erts_lc_lock_t *lck,
+lock_twice(char *prefix, lc_thread_t *thr, erts_lc_lock_t *lck,
 	   erts_lock_options_t options)
 {
     erts_fprintf(stderr, "%s (%s)", prefix, rw_op_str(options));
     print_lock(" ", lck, " lock which is already locked by thread!\n");
-    print_curr_locks(l_lcks);
+    print_curr_locks(thr);
     lc_abort();
 }
 
 static void
-unlock_op_mismatch(erts_lc_locked_locks_t *l_lcks, erts_lc_lock_t *lck,
+unlock_op_mismatch(lc_thread_t *thr, erts_lc_lock_t *lck,
 		   erts_lock_options_t options)
 {
     erts_fprintf(stderr, "Unlocking (%s) ", rw_op_str(options));
     print_lock("", lck, " lock which mismatch previous lock operation!\n");
-    print_curr_locks(l_lcks);
+    print_curr_locks(thr);
     lc_abort();
 }
 
 static void
-unlock_of_not_locked(erts_lc_locked_locks_t *l_lcks, erts_lc_lock_t *lck)
+unlock_of_not_locked(lc_thread_t *thr, erts_lc_lock_t *lck)
 {
     print_lock("Unlocking ", lck, " lock which is not locked by thread!\n");
-    print_curr_locks(l_lcks);
+    print_curr_locks(thr);
     lc_abort();
 }
 
 static void
-lock_order_violation(erts_lc_locked_locks_t *l_lcks, erts_lc_lock_t *lck)
+lock_order_violation(lc_thread_t *thr, erts_lc_lock_t *lck)
 {
     print_lock("Lock order violation occured when locking ", lck, "!\n");
-    print_curr_locks(l_lcks);
+    print_curr_locks(thr);
     print_lock_order();
     lc_abort();
 }
 
 static void
-type_order_violation(char *op, erts_lc_locked_locks_t *l_lcks,
+type_order_violation(char *op, lc_thread_t *thr,
 		     erts_lc_lock_t *lck)
 {
     erts_fprintf(stderr, "Lock type order violation occured when ");
     print_lock(op, lck, "!\n");
-    ASSERT(l_lcks);
-    print_curr_locks(l_lcks);
+    ASSERT(thr);
+    print_curr_locks(thr);
     lc_abort();
 }
 
 static void
-lock_mismatch(erts_lc_locked_locks_t *l_lcks, int exact,
+lock_mismatch(lc_thread_t *thr, int exact,
 	      int failed_have, erts_lc_lock_t *have, int have_len,
 	      int failed_have_not, erts_lc_lock_t *have_not, int have_not_len)
 {
@@ -576,39 +567,39 @@ lock_mismatch(erts_lc_locked_locks_t *l_lcks, int exact,
 		print_lock2("  ", have_not[i].id, have_not[i].extra, 0, "\n");
 	}
     }
-    print_curr_locks(l_lcks);
+    print_curr_locks(thr);
     lc_abort();
 }
 
 static void
-unlock_of_required_lock(erts_lc_locked_locks_t *l_lcks, erts_lc_lock_t *lck)
+unlock_of_required_lock(lc_thread_t *thr, erts_lc_lock_t *lck)
 {
     print_lock("Unlocking required ", lck, " lock!\n");
-    print_curr_locks(l_lcks);
+    print_curr_locks(thr);
     lc_abort();
 }
 
 static void
-unrequire_of_not_required_lock(erts_lc_locked_locks_t *l_lcks, erts_lc_lock_t *lck)
+unrequire_of_not_required_lock(lc_thread_t *thr, erts_lc_lock_t *lck)
 {
     print_lock("Unrequire on ", lck, " lock not required!\n");
-    print_curr_locks(l_lcks);
+    print_curr_locks(thr);
     lc_abort();
 }
 
 static void
-require_twice(erts_lc_locked_locks_t *l_lcks, erts_lc_lock_t *lck)
+require_twice(lc_thread_t *thr, erts_lc_lock_t *lck)
 {
     print_lock("Require on ", lck, " lock already required!\n");
-    print_curr_locks(l_lcks);
+    print_curr_locks(thr);
     lc_abort();
 }
 
 static void
-required_not_locked(erts_lc_locked_locks_t *l_lcks, erts_lc_lock_t *lck)
+required_not_locked(lc_thread_t *thr, erts_lc_lock_t *lck)
 {
     print_lock("Required ", lck, " lock not locked!\n");
-    print_curr_locks(l_lcks);
+    print_curr_locks(thr);
     lc_abort();
 }
 
@@ -616,15 +607,15 @@ required_not_locked(erts_lc_locked_locks_t *l_lcks, erts_lc_lock_t *lck)
 static void
 thread_exit_handler(void)
 {
-    erts_lc_locked_locks_t *l_lcks = get_my_locked_locks();
-    if (l_lcks) {
-	if (l_lcks->locked.first) {
+    lc_thread_t *thr = get_my_locked_locks();
+    if (thr) {
+	if (thr->locked.first) {
 	    erts_fprintf(stderr,
 			 "Thread exiting while having locked locks!\n");
-	    print_curr_locks(l_lcks);
+	    print_curr_locks(thr);
 	    lc_abort();
 	}
-	destroy_locked_locks(l_lcks);
+	destroy_locked_locks(thr);
 	/* erts_tsd_set(locks_key, NULL); */
     }
 }
@@ -642,24 +633,24 @@ lc_abort(void)
 void
 erts_lc_set_thread_name(char *thread_name)
 {
-    erts_lc_locked_locks_t *l_lcks = get_my_locked_locks();
-    if (!l_lcks)
-	l_lcks = create_locked_locks(thread_name);
+    lc_thread_t *thr = get_my_locked_locks();
+    if (!thr)
+	thr = create_thread_data(thread_name);
     else {
-	ASSERT(l_lcks->thread_name);
-	free((void *) l_lcks->thread_name);
-	l_lcks->thread_name = strdup(thread_name ? thread_name : "unknown");
-	if (!l_lcks->thread_name)
+	ASSERT(thr->thread_name);
+	free((void *) thr->thread_name);
+	thr->thread_name = strdup(thread_name ? thread_name : "unknown");
+	if (!thr->thread_name)
 	    ERTS_INTERNAL_ERROR("strdup failed");
     }
-    l_lcks->emu_thread = 1;
+    thr->emu_thread = 1;
 }
 
 int
 erts_lc_is_emu_thr(void)
 {
-    erts_lc_locked_locks_t *l_lcks = get_my_locked_locks();
-    return l_lcks->emu_thread;
+    lc_thread_t *thr = get_my_locked_locks();
+    return thr->emu_thread;
 }
 
 int
@@ -705,7 +696,7 @@ erts_lc_get_lock_order_id(char *name)
     return (Sint16) -1;
 }
 
-static int compare_locked_by_id(erts_lc_locked_lock_t *locked_lock, erts_lc_lock_t *comparand)
+static int compare_locked_by_id(lc_locked_lock_t *locked_lock, erts_lc_lock_t *comparand)
 {
     if(locked_lock->id < comparand->id) {
         return -1;
@@ -716,7 +707,7 @@ static int compare_locked_by_id(erts_lc_locked_lock_t *locked_lock, erts_lc_lock
     return 0;
 }
 
-static int compare_locked_by_id_extra(erts_lc_locked_lock_t *locked_lock, erts_lc_lock_t *comparand)
+static int compare_locked_by_id_extra(lc_locked_lock_t *locked_lock, erts_lc_lock_t *comparand)
 {
     int order = compare_locked_by_id(locked_lock, comparand);
 
@@ -731,18 +722,18 @@ static int compare_locked_by_id_extra(erts_lc_locked_lock_t *locked_lock, erts_l
     return 0;
 }
 
-typedef int (*locked_compare_func)(erts_lc_locked_lock_t *, erts_lc_lock_t *);
+typedef int (*locked_compare_func)(lc_locked_lock_t *, erts_lc_lock_t *);
 
 /* Searches through a list of taken locks, bailing when it hits an entry whose
  * order relative to the search template is the opposite of the one at the
  * start of the search. (*closest_neighbor) is either set to the exact match,
  * or the one closest to it in the sort order. */
 static int search_locked_list(locked_compare_func compare,
-                              erts_lc_locked_lock_t *locked_locks,
+                              lc_locked_lock_t *locked_locks,
                               erts_lc_lock_t *search_template,
-                              erts_lc_locked_lock_t **closest_neighbor)
+                              lc_locked_lock_t **closest_neighbor)
 {
-    erts_lc_locked_lock_t *iterator = locked_locks;
+    lc_locked_lock_t *iterator = locked_locks;
 
     (*closest_neighbor) = iterator;
 
@@ -778,9 +769,9 @@ static int search_locked_list(locked_compare_func compare,
 /* Searches for a lock in the given list that matches search_template, and sets
  * (*locked_locks) to the closest lock in the sort order. */
 static int
-find_lock(erts_lc_locked_lock_t **locked_locks, erts_lc_lock_t *search_template)
+find_lock(lc_locked_lock_t **locked_locks, erts_lc_lock_t *search_template)
 {
-    erts_lc_locked_lock_t *closest_neighbor;
+    lc_locked_lock_t *closest_neighbor;
     int found_lock;
 
     found_lock = search_locked_list(compare_locked_by_id_extra,
@@ -809,9 +800,9 @@ find_lock(erts_lc_locked_lock_t **locked_locks, erts_lc_lock_t *search_template)
 /* Searches for a lock in the given list by id, and sets (*locked_locks) to the
  * closest lock in the sort order. */
 static int
-find_id(erts_lc_locked_lock_t **locked_locks, Sint16 id)
+find_id(lc_locked_lock_t **locked_locks, Sint16 id)
 {
-    erts_lc_locked_lock_t *closest_neighbor;
+    lc_locked_lock_t *closest_neighbor;
     erts_lc_lock_t search_template;
     int found_lock;
 
@@ -830,34 +821,34 @@ find_id(erts_lc_locked_lock_t **locked_locks, Sint16 id)
 void
 erts_lc_have_locks(int *resv, erts_lc_lock_t *locks, int len)
 {
-    erts_lc_locked_locks_t *l_lcks = get_my_locked_locks();
+    lc_thread_t *thr = get_my_locked_locks();
     int i;
 
-    if (!l_lcks) {
+    if (!thr) {
 	for (i = 0; i < len; i++)
 	    resv[i] = 0;
     }
     else {
-	erts_lc_locked_lock_t *l_lck = l_lcks->locked.first;
+	lc_locked_lock_t *ll = thr->locked.first;
 	for (i = 0; i < len; i++)
-	    resv[i] = find_lock(&l_lck, &locks[i]);
+	    resv[i] = find_lock(&ll, &locks[i]);
     }
 }
 
 void
 erts_lc_have_lock_ids(int *resv, int *ids, int len)
 {
-    erts_lc_locked_locks_t *l_lcks = get_my_locked_locks();
+    lc_thread_t *thr = get_my_locked_locks();
     int i;
 
-    if (!l_lcks) {
+    if (!thr) {
 	for (i = 0; i < len; i++)
 	    resv[i] = 0;
     }
     else {
-	erts_lc_locked_lock_t *l_lck = l_lcks->locked.first;
+	lc_locked_lock_t *ll = thr->locked.first;
 	for (i = 0; i < len; i++)
-	    resv[i] = find_id(&l_lck, ids[i]);
+	    resv[i] = find_id(&ll, ids[i]);
     }
 }
 
@@ -866,27 +857,27 @@ erts_lc_check(erts_lc_lock_t *have, int have_len,
 	      erts_lc_lock_t *have_not, int have_not_len)
 {
     int i;
-    erts_lc_locked_locks_t *l_lcks = get_my_locked_locks();
-    erts_lc_locked_lock_t *l_lck;
+    lc_thread_t *thr = get_my_locked_locks();
+    lc_locked_lock_t *ll;
     
     if (have && have_len > 0) {
-	if (!l_lcks)
+	if (!thr)
 	    lock_mismatch(NULL, 0,
 			  -1, have, have_len,
 			  -1, have_not, have_not_len);
-	l_lck = l_lcks->locked.first;
+	ll = thr->locked.first;
 	for (i = 0; i < have_len; i++) {
-	    if (!find_lock(&l_lck, &have[i]))
-		lock_mismatch(l_lcks, 0,
+	    if (!find_lock(&ll, &have[i]))
+		lock_mismatch(thr, 0,
 			      i, have, have_len,
 			      -1, have_not, have_not_len);
 	}
     }
-    if (have_not && have_not_len > 0 && l_lcks) {
-	l_lck = l_lcks->locked.first;
+    if (have_not && have_not_len > 0 && thr) {
+	ll = thr->locked.first;
 	for (i = 0; i < have_not_len; i++) {
-	    if (find_lock(&l_lck, &have_not[i]))
-		lock_mismatch(l_lcks, 0,
+	    if (find_lock(&ll, &have_not[i]))
+		lock_mismatch(thr, 0,
 			      -1, have, have_len,
 			      i, have_not, have_not_len);
 	}
@@ -896,8 +887,8 @@ erts_lc_check(erts_lc_lock_t *have, int have_len,
 void
 erts_lc_check_exact(erts_lc_lock_t *have, int have_len)
 {
-    erts_lc_locked_locks_t *l_lcks = get_my_locked_locks();
-    if (!l_lcks) {
+    lc_thread_t *thr = get_my_locked_locks();
+    if (!thr) {
 	if (have && have_len > 0)
 	    lock_mismatch(NULL, 1,
 			  -1, have, have_len,
@@ -905,17 +896,17 @@ erts_lc_check_exact(erts_lc_lock_t *have, int have_len)
     }
     else {
 	int i;
-	erts_lc_locked_lock_t *l_lck = l_lcks->locked.first;
+	lc_locked_lock_t *ll = thr->locked.first;
 	for (i = 0; i < have_len; i++) {
-	    if (!find_lock(&l_lck, &have[i]))
-		lock_mismatch(l_lcks, 1,
+	    if (!find_lock(&ll, &have[i]))
+		lock_mismatch(thr, 1,
 			      i, have, have_len,
 			      -1, NULL, 0);
 	}
-	for (i = 0, l_lck = l_lcks->locked.first; l_lck; l_lck = l_lck->next)
+	for (i = 0, ll = thr->locked.first; ll; ll = ll->next)
 	    i++;
 	if (i != have_len)
-	    lock_mismatch(l_lcks, 1,
+	    lock_mismatch(thr, 1,
 			  -1, have, have_len,
 			  -1, NULL, 0);
     }
@@ -924,16 +915,16 @@ erts_lc_check_exact(erts_lc_lock_t *have, int have_len)
 void
 erts_lc_check_no_locked_of_type(erts_lock_flags_t type)
 {
-    erts_lc_locked_locks_t *l_lcks = get_my_locked_locks();
-    if (l_lcks) {
-	erts_lc_locked_lock_t *l_lck = l_lcks->locked.first;
-	for (l_lck = l_lcks->locked.first; l_lck; l_lck = l_lck->next) {
-	    if ((l_lck->flags & ERTS_LOCK_FLAGS_MASK_TYPE) == type) {
+    lc_thread_t *thr = get_my_locked_locks();
+    if (thr) {
+	lc_locked_lock_t *ll = thr->locked.first;
+	for (ll = thr->locked.first; ll; ll = ll->next) {
+	    if ((ll->flags & ERTS_LOCK_FLAGS_MASK_TYPE) == type) {
 		erts_fprintf(stderr,
 			     "Locked lock of type %s found which isn't "
 			     "allowed here!\n",
-			     erts_lock_flags_get_type_name(l_lck->flags));
-		print_curr_locks(l_lcks);
+			     erts_lock_flags_get_type_name(ll->flags));
+		print_curr_locks(thr);
 		lc_abort();
 	    }
 	}
@@ -951,7 +942,7 @@ erts_lc_trylock_force_busy_flg(erts_lc_lock_t *lck, erts_lock_options_t options)
      * This in order to make sure that caller can handle
      * the situation without causing a lock order violation.
      */
-    erts_lc_locked_locks_t *l_lcks;
+    lc_thread_t *thr;
 
     if (lck->inited != ERTS_LC_INITITALIZED)
 	uninitialized_lock();
@@ -959,25 +950,25 @@ erts_lc_trylock_force_busy_flg(erts_lc_lock_t *lck, erts_lock_options_t options)
     if (lck->id < 0)
 	return 0;
 
-    l_lcks = get_my_locked_locks();
+    thr = get_my_locked_locks();
 
-    if (!l_lcks || !l_lcks->locked.first) {
-	ASSERT(!l_lcks || !l_lcks->locked.last);
+    if (!thr || !thr->locked.first) {
+	ASSERT(!thr || !thr->locked.last);
 	return 0;
     }
     else {
-	erts_lc_locked_lock_t *tl_lck;
+	lc_locked_lock_t *tl_lck;
 
-	ASSERT(l_lcks->locked.last);
+	ASSERT(thr->locked.last);
 
 #if 0 /* Ok when trylocking I guess... */
-	if (LOCK_IS_TYPE_ORDER_VIOLATION(lck->flags, l_lcks->locked.last->flags))
-	    type_order_violation("trylocking ", l_lcks, lck);
+	if (LOCK_IS_TYPE_ORDER_VIOLATION(lck->flags, thr->locked.last->flags))
+	    type_order_violation("trylocking ", thr, lck);
 #endif
 
-	if (l_lcks->locked.last->id < lck->id
-	    || (l_lcks->locked.last->id == lck->id
-		&& l_lcks->locked.last->extra < lck->extra))
+	if (thr->locked.last->id < lck->id
+	    || (thr->locked.last->id == lck->id
+		&& thr->locked.last->extra < lck->extra))
 	    return 0;
 
 	/*
@@ -986,11 +977,11 @@ erts_lc_trylock_force_busy_flg(erts_lc_lock_t *lck, erts_lock_options_t options)
 
 
 	/* Check that we are not trying to lock this lock twice */
-	for (tl_lck = l_lcks->locked.last; tl_lck; tl_lck = tl_lck->prev) {
+	for (tl_lck = thr->locked.last; tl_lck; tl_lck = tl_lck->prev) {
 	    if (tl_lck->id < lck->id
 		|| (tl_lck->id == lck->id && tl_lck->extra <= lck->extra)) {
 		if (tl_lck->id == lck->id && tl_lck->extra == lck->extra)
-		    lock_twice("Trylocking", l_lcks, lck, options);
+		    lock_twice("Trylocking", thr, lck, options);
 		break;
 	    }
 	}
@@ -1015,8 +1006,8 @@ erts_lc_trylock_force_busy_flg(erts_lc_lock_t *lck, erts_lock_options_t options)
 void erts_lc_trylock_flg_x(int locked, erts_lc_lock_t *lck, erts_lock_options_t options,
 			   char *file, unsigned int line)
 {
-    erts_lc_locked_locks_t *l_lcks;
-    erts_lc_locked_lock_t *l_lck;
+    lc_thread_t *thr;
+    lc_locked_lock_t *ll;
 
     if (lck->inited != ERTS_LC_INITITALIZED)
 	uninitialized_lock();
@@ -1024,43 +1015,43 @@ void erts_lc_trylock_flg_x(int locked, erts_lc_lock_t *lck, erts_lock_options_t
     if (lck->id < 0)
 	return;
 
-    l_lcks = make_my_locked_locks();
-    l_lck = locked ? new_locked_lock(lck, options, file, line) : NULL;
+    thr = make_my_locked_locks();
+    ll = locked ? new_locked_lock(thr, lck, options, file, line) : NULL;
 
-    if (!l_lcks->locked.last) {
-	ASSERT(!l_lcks->locked.first);
+    if (!thr->locked.last) {
+	ASSERT(!thr->locked.first);
 	if (locked)
-	    l_lcks->locked.first = l_lcks->locked.last = l_lck;
+	    thr->locked.first = thr->locked.last = ll;
     }
     else {
-	erts_lc_locked_lock_t *tl_lck;
+	lc_locked_lock_t *tl_lck;
 #if 0 /* Ok when trylocking I guess... */
-	if (LOCK_IS_TYPE_ORDER_VIOLATION(lck->flags, l_lcks->locked.last->flags))
-	    type_order_violation("trylocking ", l_lcks, lck);
+	if (LOCK_IS_TYPE_ORDER_VIOLATION(lck->flags, thr->locked.last->flags))
+	    type_order_violation("trylocking ", thr, lck);
 #endif
 
-	for (tl_lck = l_lcks->locked.last; tl_lck; tl_lck = tl_lck->prev) {
+	for (tl_lck = thr->locked.last; tl_lck; tl_lck = tl_lck->prev) {
 	    if (tl_lck->id < lck->id
 		|| (tl_lck->id == lck->id && tl_lck->extra <= lck->extra)) {
 		if (tl_lck->id == lck->id && tl_lck->extra == lck->extra)
-		    lock_twice("Trylocking", l_lcks, lck, options);
+		    lock_twice("Trylocking", thr, lck, options);
 		if (locked) {
-		    l_lck->next = tl_lck->next;
-		    l_lck->prev = tl_lck;
+		    ll->next = tl_lck->next;
+		    ll->prev = tl_lck;
 		    if (tl_lck->next)
-			tl_lck->next->prev = l_lck;
+			tl_lck->next->prev = ll;
 		    else
-			l_lcks->locked.last = l_lck;
-		    tl_lck->next = l_lck;
+			thr->locked.last = ll;
+		    tl_lck->next = ll;
 		}
 		return;
 	    }
 	}
 
 	if (locked) {
-	    l_lck->next = l_lcks->locked.first;
-	    l_lcks->locked.first->prev = l_lck;
-	    l_lcks->locked.first = l_lck;
+	    ll->next = thr->locked.first;
+	    thr->locked.first->prev = ll;
+	    thr->locked.first = ll;
 	}
     }
 
@@ -1069,83 +1060,83 @@ void erts_lc_trylock_flg_x(int locked, erts_lc_lock_t *lck, erts_lock_options_t
 void erts_lc_require_lock_flg(erts_lc_lock_t *lck, erts_lock_options_t options,
 			      char *file, unsigned int line)
 {
-    erts_lc_locked_locks_t *l_lcks = make_my_locked_locks();
-    erts_lc_locked_lock_t *l_lck = l_lcks->locked.first;
-    if (!find_lock(&l_lck, lck))
-	required_not_locked(l_lcks, lck);
-    l_lck = new_locked_lock(lck, options, file, line);
-    if (!l_lcks->required.last) {
-	ASSERT(!l_lcks->required.first);
-	l_lck->next = l_lck->prev = NULL;
-	l_lcks->required.first = l_lcks->required.last = l_lck;
+    lc_thread_t *thr = make_my_locked_locks();
+    lc_locked_lock_t *ll = thr->locked.first;
+    if (!find_lock(&ll, lck))
+	required_not_locked(thr, lck);
+    ll = new_locked_lock(thr, lck, options, file, line);
+    if (!thr->required.last) {
+	ASSERT(!thr->required.first);
+	ll->next = ll->prev = NULL;
+	thr->required.first = thr->required.last = ll;
     }
     else {
-	erts_lc_locked_lock_t *l_lck2;
-	ASSERT(l_lcks->required.first);
-	for (l_lck2 = l_lcks->required.last;
+	lc_locked_lock_t *l_lck2;
+	ASSERT(thr->required.first);
+	for (l_lck2 = thr->required.last;
 	     l_lck2;
 	     l_lck2 = l_lck2->prev) {
 	    if (l_lck2->id < lck->id
 		|| (l_lck2->id == lck->id && l_lck2->extra < lck->extra))
 		break;
 	    else if (l_lck2->id == lck->id && l_lck2->extra == lck->extra)
-		require_twice(l_lcks, lck);
+		require_twice(thr, lck);
 	}
 	if (!l_lck2) {
-	    l_lck->next = l_lcks->required.first;
-	    l_lck->prev = NULL;
-	    l_lcks->required.first->prev = l_lck;
-	    l_lcks->required.first = l_lck;
+	    ll->next = thr->required.first;
+	    ll->prev = NULL;
+	    thr->required.first->prev = ll;
+	    thr->required.first = ll;
 	}
 	else {
-	    l_lck->next = l_lck2->next;
-	    if (l_lck->next) {
-		ASSERT(l_lcks->required.last != l_lck2);
-		l_lck->next->prev = l_lck;
+	    ll->next = l_lck2->next;
+	    if (ll->next) {
+		ASSERT(thr->required.last != l_lck2);
+		ll->next->prev = ll;
 	    }
 	    else {
-		ASSERT(l_lcks->required.last == l_lck2);
-		l_lcks->required.last = l_lck;
+		ASSERT(thr->required.last == l_lck2);
+		thr->required.last = ll;
 	    }
-	    l_lck->prev = l_lck2;
-	    l_lck2->next = l_lck;		
+	    ll->prev = l_lck2;
+	    l_lck2->next = ll;
 	}
     }
 }
 
 void erts_lc_unrequire_lock_flg(erts_lc_lock_t *lck, erts_lock_options_t options)
 {
-    erts_lc_locked_locks_t *l_lcks = make_my_locked_locks();
-    erts_lc_locked_lock_t *l_lck = l_lcks->locked.first;
-    if (!find_lock(&l_lck, lck))
-	required_not_locked(l_lcks, lck);
-    l_lck = l_lcks->required.first;
-    if (!find_lock(&l_lck, lck))
-	unrequire_of_not_required_lock(l_lcks, lck);
-    if (l_lck->prev) {
-	ASSERT(l_lcks->required.first != l_lck);
-	l_lck->prev->next = l_lck->next;
+    lc_thread_t *thr = make_my_locked_locks();
+    lc_locked_lock_t *ll = thr->locked.first;
+    if (!find_lock(&ll, lck))
+	required_not_locked(thr, lck);
+    ll = thr->required.first;
+    if (!find_lock(&ll, lck))
+	unrequire_of_not_required_lock(thr, lck);
+    if (ll->prev) {
+	ASSERT(thr->required.first != ll);
+	ll->prev->next = ll->next;
     }
     else {
-	ASSERT(l_lcks->required.first == l_lck);
-	l_lcks->required.first = l_lck->next;
+	ASSERT(thr->required.first == ll);
+	thr->required.first = ll->next;
     }
-    if (l_lck->next) {
-	ASSERT(l_lcks->required.last != l_lck);
-	l_lck->next->prev = l_lck->prev;
+    if (ll->next) {
+	ASSERT(thr->required.last != ll);
+	ll->next->prev = ll->prev;
     }
     else {
-	ASSERT(l_lcks->required.last == l_lck);
-	l_lcks->required.last = l_lck->prev;
+	ASSERT(thr->required.last == ll);
+	thr->required.last = ll->prev;
     }
-    lc_free((void *) l_lck);
+    lc_free(thr, ll);
 }
 
 void erts_lc_lock_flg_x(erts_lc_lock_t *lck, erts_lock_options_t options,
 			char *file, unsigned int line)
 {
-    erts_lc_locked_locks_t *l_lcks;
-    erts_lc_locked_lock_t *l_lck;
+    lc_thread_t *thr;
+    lc_locked_lock_t *new_ll;
 
     if (lck->inited != ERTS_LC_INITITALIZED)
 	uninitialized_lock();
@@ -1153,32 +1144,45 @@ void erts_lc_lock_flg_x(erts_lc_lock_t *lck, erts_lock_options_t options,
     if (lck->id < 0)
 	return;
 
-    l_lcks = make_my_locked_locks();
-    l_lck = new_locked_lock(lck, options, file, line);
+    thr = make_my_locked_locks();
+    new_ll = new_locked_lock(thr, lck, options, file, line);
 
-    if (!l_lcks->locked.last) {
-	ASSERT(!l_lcks->locked.first);
-	l_lcks->locked.last = l_lcks->locked.first = l_lck;
+    if (!thr->locked.last) {
+	ASSERT(!thr->locked.first);
+	thr->locked.last = thr->locked.first = new_ll;
+        ASSERT(0 < lck->id && lck->id < ERTS_LOCK_ORDER_SIZE);
+        thr->matrix.m[lck->id][0] = 1;
     }
-    else if (l_lcks->locked.last->id < lck->id
-	     || (l_lcks->locked.last->id == lck->id
-		 && l_lcks->locked.last->extra < lck->extra)) {
-	if (LOCK_IS_TYPE_ORDER_VIOLATION(lck->flags, l_lcks->locked.last->flags))
-	    type_order_violation("locking ", l_lcks, lck);
-	l_lck->prev = l_lcks->locked.last;
-	l_lcks->locked.last->next = l_lck;
-	l_lcks->locked.last = l_lck;
+    else if (thr->locked.last->id < lck->id
+	     || (thr->locked.last->id == lck->id
+		 && thr->locked.last->extra < lck->extra)) {
+        lc_locked_lock_t* ll;
+	if (LOCK_IS_TYPE_ORDER_VIOLATION(lck->flags, thr->locked.last->flags)) {
+	    type_order_violation("locking ", thr, lck);
+        }
+
+        ASSERT(0 < lck->id && lck->id < ERTS_LOCK_ORDER_SIZE);
+        ll = thr->locked.last;
+        thr->matrix.m[lck->id][ll->id] |= 1;
+        for (ll = ll->prev; ll; ll = ll->prev) {
+            ASSERT(0 < ll->id && ll->id < ERTS_LOCK_ORDER_SIZE);
+            thr->matrix.m[lck->id][ll->id] |= 2;
+        }
+
+	new_ll->prev = thr->locked.last;
+	thr->locked.last->next = new_ll;
+	thr->locked.last = new_ll;
     }
-    else if (l_lcks->locked.last->id == lck->id && l_lcks->locked.last->extra == lck->extra)
-	lock_twice("Locking", l_lcks, lck, options);
+    else if (thr->locked.last->id == lck->id && thr->locked.last->extra == lck->extra)
+	lock_twice("Locking", thr, lck, options);
     else
-	lock_order_violation(l_lcks, lck);
+	lock_order_violation(thr, lck);
 }
 
 void erts_lc_unlock_flg(erts_lc_lock_t *lck, erts_lock_options_t options)
 {
-    erts_lc_locked_locks_t *l_lcks;
-    erts_lc_locked_lock_t *l_lck;
+    lc_thread_t *thr;
+    lc_locked_lock_t *ll;
 
     if (lck->inited != ERTS_LC_INITITALIZED)
 	uninitialized_lock();
@@ -1186,38 +1190,38 @@ void erts_lc_unlock_flg(erts_lc_lock_t *lck, erts_lock_options_t options)
     if (lck->id < 0)
 	return;
 
-    l_lcks = get_my_locked_locks();
+    thr = get_my_locked_locks();
 
-    if (l_lcks) {
-	l_lck = l_lcks->required.first;
-	if (find_lock(&l_lck, lck))
-	    unlock_of_required_lock(l_lcks, lck);
+    if (thr) {
+	ll = thr->required.first;
+	if (find_lock(&ll, lck))
+	    unlock_of_required_lock(thr, lck);
     }
 
-    for (l_lck = l_lcks ? l_lcks->locked.last : NULL; l_lck; l_lck = l_lck->prev) {
-	if (l_lck->id == lck->id && l_lck->extra == lck->extra) {
-	    if ((l_lck->taken_options & ERTS_LOCK_OPTIONS_RDWR) != options)
-		unlock_op_mismatch(l_lcks, lck, options);
-	    if (l_lck->prev)
-		l_lck->prev->next = l_lck->next;
+    for (ll = thr ? thr->locked.last : NULL; ll; ll = ll->prev) {
+	if (ll->id == lck->id && ll->extra == lck->extra) {
+	    if ((ll->taken_options & ERTS_LOCK_OPTIONS_RDWR) != options)
+		unlock_op_mismatch(thr, lck, options);
+	    if (ll->prev)
+		ll->prev->next = ll->next;
 	    else
-		l_lcks->locked.first = l_lck->next;
-	    if (l_lck->next)
-		l_lck->next->prev = l_lck->prev;
+		thr->locked.first = ll->next;
+	    if (ll->next)
+		ll->next->prev = ll->prev;
 	    else
-		l_lcks->locked.last = l_lck->prev;
-	    lc_free((void *) l_lck);
+		thr->locked.last = ll->prev;
+	    lc_free(thr, ll);
 	    return;
 	}
     }
     
-    unlock_of_not_locked(l_lcks, lck);
+    unlock_of_not_locked(thr, lck);
 }
 
 void erts_lc_might_unlock_flg(erts_lc_lock_t *lck, erts_lock_options_t options)
 {
-    erts_lc_locked_locks_t *l_lcks;
-    erts_lc_locked_lock_t *l_lck;
+    lc_thread_t *thr;
+    lc_locked_lock_t *ll;
 
     if (lck->inited != ERTS_LC_INITITALIZED)
 	uninitialized_lock();
@@ -1225,17 +1229,17 @@ void erts_lc_might_unlock_flg(erts_lc_lock_t *lck, erts_lock_options_t options)
     if (lck->id < 0)
 	return;
 
-    l_lcks = get_my_locked_locks();
+    thr = get_my_locked_locks();
 
-    if (l_lcks) {
-	l_lck = l_lcks->required.first;
-	if (find_lock(&l_lck, lck))
-	    unlock_of_required_lock(l_lcks, lck);
+    if (thr) {
+	ll = thr->required.first;
+	if (find_lock(&ll, lck))
+	    unlock_of_required_lock(thr, lck);
     }
 
-    l_lck = l_lcks->locked.first;
-    if (!find_lock(&l_lck, lck))
-	unlock_of_not_locked(l_lcks, lck);
+    ll = thr->locked.first;
+    if (!find_lock(&ll, lck))
+	unlock_of_not_locked(thr, lck);
 }
 
 int
@@ -1316,26 +1320,7 @@ erts_lc_destroy_lock(erts_lc_lock_t *lck)
 void
 erts_lc_init(void)
 {
-#ifdef ERTS_LC_STATIC_ALLOC
-    int i;
-    static erts_lc_free_block_t fbs[ERTS_LC_FB_CHUNK_SIZE];
-    for (i = 0; i < ERTS_LC_FB_CHUNK_SIZE - 1; i++) {
-#ifdef DEBUG
-	sys_memset((void *) &fbs[i], 0xdf, sizeof(erts_lc_free_block_t));
-#endif
-	fbs[i].next = &fbs[i+1];
-    }
-#ifdef DEBUG
-    sys_memset((void *) &fbs[ERTS_LC_FB_CHUNK_SIZE-1],
-	   0xdf, sizeof(erts_lc_free_block_t));
-#endif
-    fbs[ERTS_LC_FB_CHUNK_SIZE-1].next = NULL;
-    free_blocks = &fbs[0]; 
-#else /* #ifdef ERTS_LC_STATIC_ALLOC */
-    free_blocks = NULL;
-#endif /* #ifdef ERTS_LC_STATIC_ALLOC */
-
-    if (ethr_spinlock_init(&free_blocks_lock) != 0)
+    if (ethr_spinlock_init(&lc_threads_lock) != 0)
 	ERTS_INTERNAL_ERROR("spinlock_init failed");
 
     erts_tsd_key_create(&locks_key,"erts_lock_check_key");
@@ -1357,5 +1342,76 @@ erts_lc_pll(void)
     print_curr_locks(get_my_locked_locks());
 }
 
+static void collect_matrix(lc_matrix_t* matrix)
+{
+    int i, j;
+    for (i = 1; i < ERTS_LOCK_ORDER_SIZE; i++) {
+        for (j = 0; j <= i; j++) {
+            tot_lc_matrix.m[i][j] |= matrix->m[i][j];
+        }
+#ifdef DEBUG
+        for ( ; j < ERTS_LOCK_ORDER_SIZE; j++) {
+            ASSERT(matrix->m[i][j] == 0);
+        }
+#endif
+    }
+}
+
+Eterm
+erts_lc_dump_graph(void)
+{
+    const char* basename = "lc_graph.";
+    char filename[40];
+    lc_matrix_t* tot = &tot_lc_matrix;
+    lc_thread_t* thr;
+    int i, j, name_max = 0;
+    FILE* ff;
+
+    lc_lock_threads();
+    for (thr = lc_threads; thr; thr = thr->next) {
+        collect_matrix(&thr->matrix);
+    }
+    lc_unlock_threads();
+
+    sys_strcpy(filename, basename);
+    sys_get_pid(filename + strlen(basename),
+                sizeof(filename) - strlen(basename));
+    ff = fopen(filename, "w");
+    if (!ff)
+        return am_error;
+
+    for (i = 1; i < ERTS_LOCK_ORDER_SIZE; i++) {
+        int len = strlen(erts_lock_order[i].name);
+        if (name_max < len)
+            name_max = len;
+    }
+    fputs("%This file was generated by erts_debug:lc_graph()\n\n", ff);
+    fputs("%{ThisLockName, ThisLockId, LockedDirectlyBeforeThis, LockedIndirectlyBeforeThis}\n", ff);
+    fprintf(ff, "[{%*s, %2d}", name_max, "\"NO LOCK\"", 0);
+    for (i = 1; i < ERTS_LOCK_ORDER_SIZE; i++) {
+        char* delim = "";
+        fprintf(ff, ",\n {%*s, %2d, [", name_max, erts_lock_order[i].name, i);
+        for (j = 0; j < ERTS_LOCK_ORDER_SIZE; j++) {
+            if (tot->m[i][j] & 1) {
+                fprintf(ff, "%s%d", delim, j);
+                delim = ",";
+            }
+        }
+        fprintf(ff, "], [");
+        delim = "";
+        for (j = 0; j < ERTS_LOCK_ORDER_SIZE; j++) {
+            if (tot->m[i][j] == 2) {
+                fprintf(ff, "%s%d", delim, j);
+                delim = ",";
+            }
+        }
+        fputs("]}", ff);
+    }
+    fputs("].", ff);
+    fclose(ff);
+    erts_fprintf(stderr, "Created file '%s' in current working directory\n",
+                 filename);
+    return am_ok;
+}
 
 #endif /* #ifdef ERTS_ENABLE_LOCK_CHECK */
diff --git a/erts/emulator/beam/erl_lock_check.h b/erts/emulator/beam/erl_lock_check.h
index 5c2c38e8f2..138bc810bd 100644
--- a/erts/emulator/beam/erl_lock_check.h
+++ b/erts/emulator/beam/erl_lock_check.h
@@ -94,6 +94,8 @@ void erts_lc_unrequire_lock(erts_lc_lock_t *lck);
 
 int erts_lc_is_emu_thr(void);
 
+Eterm erts_lc_dump_graph(void);
+
 #define ERTS_LC_ASSERT(A) \
     ((void) (((A) || ERTS_SOMEONE_IS_CRASH_DUMPING) ? 1 : erts_lc_assert_failed(__FILE__, __LINE__, #A)))
 #else /* #ifdef ERTS_ENABLE_LOCK_CHECK */
diff --git a/erts/emulator/test/z_SUITE.erl b/erts/emulator/test/z_SUITE.erl
index ac3df8bfbf..103f9f1550 100644
--- a/erts/emulator/test/z_SUITE.erl
+++ b/erts/emulator/test/z_SUITE.erl
@@ -37,6 +37,7 @@
 -export([schedulers_alive/1, node_container_refc_check/1,
 	 long_timers/1, pollset_size/1,
 	 check_io_debug/1, get_check_io_info/0,
+         lc_graph/1,
          leaked_processes/1]).
 
 suite() ->
@@ -46,6 +47,7 @@ suite() ->
 all() -> 
     [schedulers_alive, node_container_refc_check,
      long_timers, pollset_size, check_io_debug,
+     lc_graph,
      %% Make sure that the leaked_processes/1 is always
      %% run last.
      leaked_processes].
@@ -289,6 +291,12 @@ has_gethost([P|T]) ->
 has_gethost([]) ->
     false.
 
+lc_graph(Config) when is_list(Config) ->
+    %% Create "lc_graph" file in current working dir
+    %% if lock checker is enabled
+    erts_debug:lc_graph(),
+    ok.
+
 leaked_processes(Config) when is_list(Config) ->
     %% Replace the defualt timetrap with a timetrap with
     %% known pid.
diff --git a/lib/kernel/src/erts_debug.erl b/lib/kernel/src/erts_debug.erl
index 6f248626ca..1270de4144 100644
--- a/lib/kernel/src/erts_debug.erl
+++ b/lib/kernel/src/erts_debug.erl
@@ -35,7 +35,8 @@
          flat_size/1, get_internal_state/1, instructions/0,
          map_info/1, same/2, set_internal_state/2,
          size_shared/1, copy_shared/1, dirty_cpu/2, dirty_io/2, dirty/3,
-         lcnt_control/1, lcnt_control/2, lcnt_collect/0, lcnt_clear/0]).
+         lcnt_control/1, lcnt_control/2, lcnt_collect/0, lcnt_clear/0,
+         lc_graph/0, lc_graph_to_dot/2, lc_graph_merge/2]).
 
 -spec breakpoint(MFA, Flag) -> non_neg_integer() when
       MFA :: {Module :: module(),
@@ -407,3 +408,90 @@ cont_dis(_, {_,_,_}, _) -> ok.
 
 map_info(_) ->
     erlang:nif_error(undef).
+
+%% Create file "lc_graph.<pid>" with all actual lock dependencies
+%% recorded so far by the VM.
+%% Needs debug VM or --enable-lock-checking config, returns 'notsup' otherwise.
+lc_graph() ->
+    erts_debug:set_internal_state(available_internal_state, true),
+    erts_debug:get_internal_state(lc_graph).
+
+%% Convert "lc_graph.<pid>" file to https://www.graphviz.org dot format.
+lc_graph_to_dot(OutFile, InFile) ->
+    {ok, [LL0]} = file:consult(InFile),
+
+    [{"NO LOCK",0} | LL] = LL0,
+    Map = maps:from_list([{Id, Name} || {Name, Id, _, _} <- LL]),
+
+    case file:open(OutFile, [exclusive]) of
+        {ok, Out} ->
+            ok = file:write(Out, "digraph G {\n"),
+
+            [dot_print_lock(Out, Lck, Map) || Lck <- LL],
+
+            ok = file:write(Out, "}\n"),
+            ok = file:close(Out);
+
+        {error,eexist} ->
+            {"File already exists", OutFile}
+    end.
+
+dot_print_lock(Out, {_Name, Id, Lst, _}, Map) ->
+    [dot_print_edge(Out, From, Id, Map) || From <- Lst],
+    ok.
+
+dot_print_edge(_, 0, _, _) ->
+    ignore; % "NO LOCK"
+dot_print_edge(Out, From, To, Map) ->
+    io:format(Out, "~p -> ~p;\n", [maps:get(From,Map), maps:get(To,Map)]).
+
+
+%% Merge several "lc_graph" files into one file.
+lc_graph_merge(OutFile, InFiles) ->
+    LLs = lists:map(fun(InFile) ->
+                            {ok, [LL]} = file:consult(InFile),
+                            LL
+                    end,
+                    InFiles),
+
+    Res = lists:foldl(fun(A, B) -> lcg_merge(A, B) end,
+                      hd(LLs),
+                      tl(LLs)),
+    case file:open(OutFile, [exclusive]) of
+        {ok, Out} ->
+            try
+                lcg_print(Out, Res)
+            after
+                file:close(Out)
+            end,
+            ok;
+        {error, eexist} ->
+            {"File already exists", OutFile}
+    end.
+
+lcg_merge(A, B) ->
+    lists:zipwith(fun(LA, LB) -> lcg_merge_locks(LA, LB) end,
+                  A, B).
+
+lcg_merge_locks(L, L) ->
+    L;
+lcg_merge_locks({Name, Id, DA, IA}, {Name, Id, DB, IB}) ->
+    Direct = lists:umerge(DA, DB),
+    Indirect = lists:umerge(IA, IB),
+    {Name, Id, Direct, Indirect -- Direct}.
+
+
+lcg_print(Out, LL) ->
+    io:format(Out, "[", []),
+    lcg_print_locks(Out, LL),
+    io:format(Out, "].\n", []),
+    ok.
+
+lcg_print_locks(Out, [{_,_}=NoLock | Rest]) ->
+    io:format(Out, "~p,\n", [NoLock]),
+    lcg_print_locks(Out, Rest);
+lcg_print_locks(Out, [LastLock]) ->
+    io:format(Out, "~w", [LastLock]);
+lcg_print_locks(Out, [Lock | Rest]) ->
+    io:format(Out, "~w,\n", [Lock]),
+    lcg_print_locks(Out, Rest).
diff --git a/lib/kernel/test/Makefile b/lib/kernel/test/Makefile
index efe3a68531..03b6355056 100644
--- a/lib/kernel/test/Makefile
+++ b/lib/kernel/test/Makefile
@@ -80,7 +80,8 @@ MODULES= \
 	loose_node \
 	sendfile_SUITE \
 	standard_error_SUITE \
-	multi_load_SUITE
+	multi_load_SUITE \
+	zzz_SUITE
 
 APP_FILES = \
 	appinc.app \
diff --git a/lib/kernel/test/zzz_SUITE.erl b/lib/kernel/test/zzz_SUITE.erl
new file mode 100644
index 0000000000..59c7fd7404
--- /dev/null
+++ b/lib/kernel/test/zzz_SUITE.erl
@@ -0,0 +1,37 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2006-2018. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(zzz_SUITE).
+
+%% The sole purpose of this test suite is for things we want to run last
+%% before the VM terminates.
+
+-export([all/0]).
+
+-export([lc_graph/1]).
+
+
+all() ->
+    [lc_graph].
+
+lc_graph(_Config) ->
+    %% Create "lc_graph" file in current working dir
+    %% if lock checker is enabled.
+    erts_debug:lc_graph(),
+    ok.
diff --git a/lib/runtime_tools/test/Makefile b/lib/runtime_tools/test/Makefile
index de37b2570d..29cf7545c9 100644
--- a/lib/runtime_tools/test/Makefile
+++ b/lib/runtime_tools/test/Makefile
@@ -10,7 +10,8 @@ MODULES =  \
 	dbg_SUITE \
 	erts_alloc_config_SUITE \
 	scheduler_SUITE \
-	msacc_SUITE
+	msacc_SUITE \
+	zzz_SUITE
 
 ERL_FILES= $(MODULES:%=%.erl)
 
diff --git a/lib/runtime_tools/test/zzz_SUITE.erl b/lib/runtime_tools/test/zzz_SUITE.erl
new file mode 100644
index 0000000000..59c7fd7404
--- /dev/null
+++ b/lib/runtime_tools/test/zzz_SUITE.erl
@@ -0,0 +1,37 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2006-2018. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(zzz_SUITE).
+
+%% The sole purpose of this test suite is for things we want to run last
+%% before the VM terminates.
+
+-export([all/0]).
+
+-export([lc_graph/1]).
+
+
+all() ->
+    [lc_graph].
+
+lc_graph(_Config) ->
+    %% Create "lc_graph" file in current working dir
+    %% if lock checker is enabled.
+    erts_debug:lc_graph(),
+    ok.
diff --git a/lib/stdlib/test/Makefile b/lib/stdlib/test/Makefile
index 8490770f3d..ae2e3d0e2b 100644
--- a/lib/stdlib/test/Makefile
+++ b/lib/stdlib/test/Makefile
@@ -95,7 +95,8 @@ MODULES= \
 	random_unicode_list \
 	random_iolist \
 	error_logger_forwarder \
-	maps_SUITE
+	maps_SUITE \
+	zzz_SUITE
 
 ERL_FILES= $(MODULES:%=%.erl)
 
diff --git a/lib/stdlib/test/zzz_SUITE.erl b/lib/stdlib/test/zzz_SUITE.erl
new file mode 100644
index 0000000000..59c7fd7404
--- /dev/null
+++ b/lib/stdlib/test/zzz_SUITE.erl
@@ -0,0 +1,37 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2006-2018. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(zzz_SUITE).
+
+%% The sole purpose of this test suite is for things we want to run last
+%% before the VM terminates.
+
+-export([all/0]).
+
+-export([lc_graph/1]).
+
+
+all() ->
+    [lc_graph].
+
+lc_graph(_Config) ->
+    %% Create "lc_graph" file in current working dir
+    %% if lock checker is enabled.
+    erts_debug:lc_graph(),
+    ok.