From 3ee8e06e8102b63c24df0b443027853cdf99549f Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas@erlang.org>
Date: Thu, 21 Feb 2019 15:38:12 +0100
Subject: erts: Add debug dist obuf memory leak check

---
 erts/emulator/beam/dist.c           | 65 +++++++++++++++++++++++++++++++++++--
 erts/emulator/beam/erl_init.c       |  5 +++
 erts/emulator/beam/erl_lock_check.c |  3 +-
 3 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/erts/emulator/beam/dist.c b/erts/emulator/beam/dist.c
index 7856d8003c..b50c8273b1 100644
--- a/erts/emulator/beam/dist.c
+++ b/erts/emulator/beam/dist.c
@@ -772,25 +772,77 @@ void init_dist(void)
 
 #define ErtsDistOutputBuf2Binary(OB) OB->bin
 
+#ifdef DEBUG
+
+struct obuf_list;
+struct obuf_list {
+    erts_refc_t refc;
+    struct obuf_list *next;
+    struct obuf_list *prev;
+};
+#define obuf_list_size sizeof(struct obuf_list)
+static struct obuf_list *erts_obuf_list = NULL;
+static erts_mtx_t erts_obuf_list_mtx;
+
+static void
+insert_obuf(struct obuf_list *obuf, erts_aint_t initial) {
+    erts_mtx_lock(&erts_obuf_list_mtx);
+    obuf->next = erts_obuf_list;
+    obuf->prev = NULL;
+    erts_refc_init(&obuf->refc, initial);
+    if (erts_obuf_list)
+        erts_obuf_list->prev = obuf;
+    erts_obuf_list = obuf;
+    erts_mtx_unlock(&erts_obuf_list_mtx);
+}
+
+static void
+remove_obuf(struct obuf_list *obuf) {
+    if (erts_refc_dectest(&obuf->refc, 0) == 0) {
+        erts_mtx_lock(&erts_obuf_list_mtx);
+        if (obuf->prev) {
+            obuf->prev->next = obuf->next;
+        } else {
+            erts_obuf_list = obuf->next;
+        }
+        if (obuf->next) obuf->next->prev = obuf->prev;
+        erts_mtx_unlock(&erts_obuf_list_mtx);
+    }
+}
+
+void check_obuf(void);
+void check_obuf(void) {
+    erts_mtx_lock(&erts_obuf_list_mtx);
+    ERTS_ASSERT(erts_obuf_list == NULL);
+    erts_mtx_unlock(&erts_obuf_list_mtx);
+}
+#else
+#define insert_obuf(...)
+#define remove_obuf(...)
+#define obuf_list_size 0
+#endif
+
 static ERTS_INLINE ErtsDistOutputBuf *
 alloc_dist_obuf(Uint size, Uint headers)
 {
     int i;
     ErtsDistOutputBuf *obuf;
     Uint obuf_size = sizeof(ErtsDistOutputBuf)*(headers) +
-        sizeof(byte)*size;
+        sizeof(byte)*size + obuf_list_size;
     Binary *bin = erts_bin_drv_alloc(obuf_size);
+    size += obuf_list_size;
     obuf = (ErtsDistOutputBuf *) &bin->orig_bytes[size];
     erts_refc_add(&bin->intern.refc, headers - 1, 1);
     for (i = 0; i < headers; i++) {
         obuf[i].bin = bin;
-        obuf[i].extp = (byte *)&bin->orig_bytes[0];
+        obuf[i].extp = (byte *)&bin->orig_bytes[0] + obuf_list_size;
 #ifdef DEBUG
         obuf[i].dbg_pattern = ERTS_DIST_OUTPUT_BUF_DBG_PATTERN;
         obuf[i].alloc_endp = obuf->extp + size;
         ASSERT(bin == ErtsDistOutputBuf2Binary(obuf));
 #endif
     }
+    insert_obuf((struct obuf_list*)&bin->orig_bytes[0], headers);
     return obuf;
 }
 
@@ -799,7 +851,10 @@ free_dist_obuf(ErtsDistOutputBuf *obuf)
 {
     Binary *bin = ErtsDistOutputBuf2Binary(obuf);
     ASSERT(obuf->dbg_pattern == ERTS_DIST_OUTPUT_BUF_DBG_PATTERN);
-    erts_bin_release(bin);
+    remove_obuf((struct obuf_list*)&bin->orig_bytes[0]);
+    if (erts_refc_dectest(&bin->intern.refc, 0) == 0) {
+        erts_bin_free(bin);
+    }
 }
 
 static ERTS_INLINE Sint
@@ -4552,6 +4607,10 @@ init_nodes_monitors(void)
 {
     erts_mtx_init(&nodes_monitors_mtx, "nodes_monitors", NIL,
         ERTS_LOCK_FLAGS_PROPERTY_STATIC | ERTS_LOCK_FLAGS_CATEGORY_DISTRIBUTION);
+#ifdef DEBUG
+    erts_mtx_init(&erts_obuf_list_mtx, "sad", NIL,
+                  ERTS_LOCK_FLAGS_PROPERTY_STATIC | ERTS_LOCK_FLAGS_CATEGORY_DISTRIBUTION);
+#endif
     nodes_monitors = NULL;
     no_nodes_monitors = 0;
 }
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 12750b9aa6..82d5140d1c 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -2417,12 +2417,17 @@ erts_exit_vv(int n, int flush_async, char *fmt, va_list args1, va_list args2)
     erts_exit_epilogue();
 }
 
+void check_obuf(void);
 __decl_noreturn void __noreturn erts_exit_epilogue(void)
 {
     int n = erts_exit_code;
 
     sys_tty_reset(n);
 
+#ifdef DEBUG
+    check_obuf();
+#endif
+
     if (n == ERTS_INTR_EXIT)
 	exit(0);
     else if (n == ERTS_DUMP_EXIT)
diff --git a/erts/emulator/beam/erl_lock_check.c b/erts/emulator/beam/erl_lock_check.c
index 3aab4828cc..39eabb6710 100644
--- a/erts/emulator/beam/erl_lock_check.c
+++ b/erts/emulator/beam/erl_lock_check.c
@@ -164,7 +164,8 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {	"os_monotonic_time",			NULL			},
     {	"erts_alloc_hard_debug",		NULL			},
     {	"hard_dbg_mseg",		        NULL	                },
-    {	"erts_mmap",				NULL			}
+    {	"erts_mmap",				NULL			},
+    {   "sad", NULL}
 };
 
 #define ERTS_LOCK_ORDER_SIZE \
-- 
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