From b50650b4c56de5279395ea195e9e68b077a1d3de Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Wed, 8 Feb 2017 17:57:52 +0100
Subject: Fix aux-work timer implementation

---
 erts/emulator/beam/erl_process.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

(limited to 'erts/emulator/beam/erl_process.c')

diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 6b5b64993f..e2764cf86f 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -560,7 +560,6 @@ static int stack_element_dump(fmtfn_t to, void *to_arg, Eterm* sp, int yreg);
 
 static void aux_work_timeout(void *unused);
 static void aux_work_timeout_early_init(int no_schedulers);
-static void aux_work_timeout_late_init(void);
 static void setup_aux_work_timer(ErtsSchedulerData *esdp);
 
 static int execute_sys_tasks(Process *c_p,
@@ -2790,6 +2789,9 @@ typedef struct {
 
     int initialized;
     erts_atomic32_t refc;
+#ifdef DEBUG
+    erts_atomic32_t used;
+#endif
     erts_atomic32_t type[1];
 } ErtsAuxWorkTmo;
 
@@ -2799,6 +2801,13 @@ static ERTS_INLINE void
 start_aux_work_timer(ErtsSchedulerData *esdp)
 {
     ErtsMonotonicTime tmo = erts_get_monotonic_time(esdp);
+#ifdef DEBUG
+    Uint no = (Uint) erts_atomic32_xchg_mb(&aux_work_tmo->used,
+                                           (erts_aint32_t) esdp->no);
+    ASSERT(esdp->type == ERTS_SCHED_NORMAL);
+    ASSERT(!no);
+#endif
+
     tmo = ERTS_MONOTONIC_TO_CLKTCKS(tmo-1);
     tmo += ERTS_MSEC_TO_CLKTCKS(1000) + 1;
     erts_twheel_init_timer(&aux_work_tmo->timer.data);
@@ -2835,16 +2844,19 @@ aux_work_timeout_early_init(int no_schedulers)
     aux_work_tmo = (ErtsAuxWorkTmo *) p;
     aux_work_tmo->initialized = 0;
     erts_atomic32_init_nob(&aux_work_tmo->refc, 0);
+#ifdef DEBUG
+    erts_atomic32_init_nob(&aux_work_tmo->used, 0);
+#endif
     for (i = 0; i <= no_schedulers; i++)
 	erts_atomic32_init_nob(&aux_work_tmo->type[i], 0);
 }
 
 void
-aux_work_timeout_late_init(void)
+erts_aux_work_timeout_late_init(ErtsSchedulerData *esdp)
 {
     aux_work_tmo->initialized = 1;
-    if (erts_atomic32_read_nob(&aux_work_tmo->refc))
-	start_aux_work_timer(erts_get_scheduler_data());
+    if (erts_atomic32_read_acqb(&aux_work_tmo->refc))
+	start_aux_work_timer(esdp);
 }
 
 static void
@@ -2852,6 +2864,13 @@ aux_work_timeout(void *vesdp)
 {
     erts_aint32_t refc;
     int i;
+#ifdef DEBUG
+    ErtsSchedulerData *esdp = erts_get_scheduler_data();
+    Uint no = (Uint) erts_atomic32_xchg_mb(&aux_work_tmo->used, 0);
+    ASSERT(no == esdp->no);
+    ASSERT(esdp == (ErtsSchedulerData *) vesdp);
+#endif
+
 #ifdef ERTS_SMP
     i = 0;
 #else
@@ -6465,8 +6484,6 @@ erts_init_scheduling(int no_schedulers, int no_schedulers_online
     /* init port tasks */
     erts_port_task_init();
 
-    aux_work_timeout_late_init();
-
 #ifndef ERTS_SMP
 #ifdef ERTS_DO_VERIFY_UNUSED_TEMP_ALLOC
     erts_scheduler_data->verify_unused_temp_alloc
@@ -8752,6 +8769,9 @@ sched_thread_func(void *vesdp)
 
     erts_sched_init_time_sup(esdp);
 
+    if (no == 1)
+        erts_aux_work_timeout_late_init(esdp);
+
     (void) ERTS_RUNQ_FLGS_SET_NOB(esdp->run_queue,
 				  ERTS_RUNQ_FLG_EXEC);
 
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