From 0985a72500ecd46579f6f7462ff121cc2c015f1f Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Tue, 15 May 2018 17:46:07 +0200
Subject: Do not hold runq lock while deleting a process

---
 erts/emulator/beam/erl_process.c      | 15 ++++++++++++++-
 erts/emulator/beam/erl_process_lock.h | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

(limited to 'erts/emulator/beam')

diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index ad7ac27ac3..70c50a6911 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -9610,6 +9610,17 @@ scheduler_gc_proc(Process *c_p, int reds_left)
     return reds;
 }
 
+static void
+unlock_lock_rq(int pre_free, void *vrq)
+{
+    ErtsRunQueue *rq = vrq;
+    if (pre_free)
+        erts_runq_unlock(rq);
+    else
+        erts_runq_lock(rq);
+}
+
+
 /*
  * schedule() is called from BEAM (process_main()) or HiPE
  * (hipe_mode_switch()) when the current process is to be
@@ -9782,7 +9793,9 @@ Process *erts_schedule(ErtsSchedulerData *esdp, Process *p, int calls)
             }
 
             if (dec_refc)
-                erts_proc_dec_refc(p);
+                erts_proc_dec_refc_free_func(p,
+                                             unlock_lock_rq,
+                                             (void *) rq);
         }
 
 	ASSERT(!esdp->free_process);
diff --git a/erts/emulator/beam/erl_process_lock.h b/erts/emulator/beam/erl_process_lock.h
index 43f396c547..bd38eca4dc 100644
--- a/erts/emulator/beam/erl_process_lock.h
+++ b/erts/emulator/beam/erl_process_lock.h
@@ -921,6 +921,9 @@ ERTS_GLB_INLINE int erts_proc_trylock(Process *, ErtsProcLocks);
 
 ERTS_GLB_INLINE void erts_proc_inc_refc(Process *);
 ERTS_GLB_INLINE void erts_proc_dec_refc(Process *);
+ERTS_GLB_INLINE void erts_proc_dec_refc_free_func(Process *p,
+                                                  void (*func)(int, void *),
+                                                  void *arg);
 ERTS_GLB_INLINE void erts_proc_add_refc(Process *, Sint);
 ERTS_GLB_INLINE Sint erts_proc_read_refc(Process *);
 
@@ -993,6 +996,21 @@ ERTS_GLB_INLINE void erts_proc_dec_refc(Process *p)
     }
 }
 
+ERTS_GLB_INLINE void erts_proc_dec_refc_free_func(Process *p,
+                                                  void (*func)(int, void *),
+                                                  void *arg)
+{
+    Sint referred;
+    ASSERT(!(erts_atomic32_read_nob(&p->state) & ERTS_PSFLG_PROXY));
+    referred = erts_ptab_atmc_dec_test_refc(&p->common);
+    if (!referred) {
+	ASSERT(ERTS_PROC_IS_EXITING(p));
+        (*func)(!0, arg);
+	erts_free_proc(p);
+        (*func)(0, arg);
+    }
+}
+
 ERTS_GLB_INLINE void erts_proc_add_refc(Process *p, Sint add_refc)
 {
     Sint referred;
-- 
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