erts: Fix locking order violation for allocation wrappers

Some query functions in erl_alloc_util.c lock the allocator mutex
and then use erts_printf that in turn may call the sys allocator
through the wrappers. To avoid breaking locking order these
query functions first "pre-locks" all allocator wrappers.

1 files changed, 38 insertions, 6 deletions

diff --git a/erts/emulator/beam/erl_mtrace.c b/erts/emulator/beam/erl_mtrace.c
index e538ba30c2..c8bb126687 100644
--- a/erts/emulator/beam/erl_mtrace.c
+++ b/erts/emulator/beam/erl_mtrace.c
@@ -222,6 +222,8 @@ static byte *tracep;
 static byte *endp;
 static SysTimeval last_tv;
 
+static ErtsAllocatorWrapper_t mtrace_wrapper;
+
 #if ERTS_MTRACE_SEGMENT_ID >= ERTS_ALC_A_MIN || ERTS_MTRACE_SEGMENT_ID < 0
 #error ERTS_MTRACE_SEGMENT_ID >= ERTS_ALC_A_MIN || ERTS_MTRACE_SEGMENT_ID < 0
 #endif
@@ -555,6 +557,8 @@ write_trace_header(char *nodename, char *pid, char *hostname)
     return 1;
 }
 
+static void mtrace_pre_lock(void);
+static void mtrace_pre_unlock(void);
 static void *mtrace_alloc(ErtsAlcType_t, void *, Uint);
 static void *mtrace_realloc(ErtsAlcType_t, void *, void *, Uint);
 static void mtrace_free(ErtsAlcType_t, void *, void *);
@@ -635,12 +639,16 @@ erts_mtrace_install_wrapper_functions(void)
 	    erts_allctrs[i].free	= mtrace_free;
 	    erts_allctrs[i].extra	= (void *) &real_allctrs[i];
 	}
+	mtrace_wrapper.lock = mtrace_pre_lock;
+	mtrace_wrapper.unlock = mtrace_pre_unlock;
+	erts_allctr_wrapper_prelock_init(&mtrace_wrapper);
     }
 }
 
 void
 erts_mtrace_stop(void)
 {
+    ASSERT(!erts_is_allctr_wrapper_prelocked());
     erts_mtx_lock(&mtrace_op_mutex);
     erts_mtx_lock(&mtrace_buf_mutex);
     if (erts_mtrace_enabled) {
@@ -677,6 +685,7 @@ erts_mtrace_stop(void)
 void
 erts_mtrace_exit(Uint32 exit_value)
 {
+    ASSERT(!erts_is_allctr_wrapper_prelocked());
     erts_mtx_lock(&mtrace_op_mutex);
     erts_mtx_lock(&mtrace_buf_mutex);
     if (erts_mtrace_enabled) {
@@ -935,18 +944,33 @@ write_free_entry(byte tag,
     erts_mtx_unlock(&mtrace_buf_mutex);
 }
 
+static void mtrace_pre_lock(void)
+{
+    erts_mtx_lock(&mtrace_op_mutex);
+}
+
+static void mtrace_pre_unlock(void)
+{
+    erts_mtx_unlock(&mtrace_op_mutex);
+}
+
+
 static void *
 mtrace_alloc(ErtsAlcType_t n, void *extra, Uint size)
 {
     ErtsAllocatorFunctions_t *real_af = (ErtsAllocatorFunctions_t *) extra;
     void *res;
 
-    erts_mtx_lock(&mtrace_op_mutex);
+    if (!erts_is_allctr_wrapper_prelocked()) {
+	erts_mtx_lock(&mtrace_op_mutex);
+    }
 
     res = (*real_af->alloc)(n, real_af->extra, size);
     write_alloc_entry(ERTS_MT_ALLOC_BDY_TAG, res, n, 0, size);
 
-    erts_mtx_unlock(&mtrace_op_mutex);
+    if (!erts_is_allctr_wrapper_prelocked()) {
+	erts_mtx_unlock(&mtrace_op_mutex);
+    }
 
     return res;
 }
@@ -957,12 +981,16 @@ mtrace_realloc(ErtsAlcType_t n, void *extra, void *ptr, Uint size)
     ErtsAllocatorFunctions_t *real_af = (ErtsAllocatorFunctions_t *) extra;
     void *res;
 
-    erts_mtx_lock(&mtrace_op_mutex);
+    if (!erts_is_allctr_wrapper_prelocked()) {
+	erts_mtx_lock(&mtrace_op_mutex);
+    }
 
     res = (*real_af->realloc)(n, real_af->extra, ptr, size);
     write_realloc_entry(ERTS_MT_REALLOC_BDY_TAG, res, n, 0, ptr, size);
 
-    erts_mtx_unlock(&mtrace_op_mutex);
+    if (!erts_is_allctr_wrapper_prelocked()) {
+	erts_mtx_unlock(&mtrace_op_mutex);
+    }
 
     return res;
 
@@ -973,10 +1001,14 @@ mtrace_free(ErtsAlcType_t n, void *extra, void *ptr)
 {
     ErtsAllocatorFunctions_t *real_af = (ErtsAllocatorFunctions_t *) extra;
 
-    erts_mtx_lock(&mtrace_op_mutex);
+    if (!erts_is_allctr_wrapper_prelocked()) {
+	erts_mtx_lock(&mtrace_op_mutex);
+    }
 
     (*real_af->free)(n, real_af->extra, ptr);
-    write_free_entry(ERTS_MT_FREE_BDY_TAG, n, 0, ptr);
+    if (!erts_is_allctr_wrapper_prelocked()) {
+	write_free_entry(ERTS_MT_FREE_BDY_TAG, n, 0, ptr);
+    }
 
     erts_mtx_unlock(&mtrace_op_mutex);
 }