From 30331259830885834780d46e51969dff2002c89b Mon Sep 17 00:00:00 2001
From: ko1 <ko1@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Wed, 2 Aug 2017 21:48:51 +0000
Subject: fix stack storing for root fibers.

* cont.c (root_fiber_alloc): this function is called by fiber_current()
  and fiber_store(). fiber_current() should clear VM stack information
  in a fiber data because runnning thread knows stack information and has
  responsibility to manage it. However fiber_store() requires to remain
  VM stack information in a fiber data because the responsibility to manage
  VM stack is moved to the Fiber from the Thread (and switch to another
  fiber).

* cont.c (root_fiber_alloc): save thread's fiber and root_fiber information.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59474 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 cont.c | 10 +++++-----
 vm.c   |  4 ++++
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/cont.c b/cont.c
index a43950c6cb..7483c1c476 100644
--- a/cont.c
+++ b/cont.c
@@ -556,6 +556,7 @@ cont_restore_thread(rb_context_t *cont)
 	th->fiber = (rb_fiber_t*)cont;
     }
 
+    VM_ASSERT(th->ec.stack != NULL);
     VM_ASSERT(sth->status == THREAD_RUNNABLE);
 }
 
@@ -1288,7 +1289,6 @@ root_fiber_alloc(rb_thread_t *th)
     rb_fiber_t *fib;
     /* no need to allocate vm stack */
     fib = fiber_t_alloc(fiber_alloc(rb_cFiber));
-    fib->cont.saved_thread.ec.stack = NULL;
     fib->cont.type = ROOT_FIBER_CONTEXT;
 #if FIBER_USE_NATIVE
 #ifdef _WIN32
@@ -1297,6 +1297,7 @@ root_fiber_alloc(rb_thread_t *th)
 #endif
     fib->status = FIBER_RUNNING;
 
+    th->root_fiber = th->fiber = fib;
     return fib;
 }
 
@@ -1305,9 +1306,9 @@ fiber_current(void)
 {
     rb_thread_t *th = GET_THREAD();
     if (th->fiber == 0) {
-	/* save root */
 	rb_fiber_t *fib = root_fiber_alloc(th);
-	th->root_fiber = th->fiber = fib;
+	/* Running thread object has stack management responsibility */
+	fib->cont.saved_thread.ec.stack = NULL;
     }
     return th->fiber;
 }
@@ -1348,9 +1349,8 @@ fiber_store(rb_fiber_t *next_fib, rb_thread_t *th)
 	cont_save_thread(&fib->cont, th);
     }
     else {
-	/* create current fiber */
+	/* create root fiber */
 	fib = root_fiber_alloc(th);
-	th->root_fiber = th->fiber = fib;
     }
 
 #if FIBER_USE_NATIVE
diff --git a/vm.c b/vm.c
index 266b251485..bc944e5085 100644
--- a/vm.c
+++ b/vm.c
@@ -90,6 +90,8 @@ VM_CFP_IN_HEAP_P(const rb_thread_t *th, const rb_control_frame_t *cfp)
 {
     const VALUE *start = th->ec.stack;
     const VALUE *end = (VALUE *)th->ec.stack + th->ec.stack_size;
+    VM_ASSERT(start != NULL);
+
     if (start <= (VALUE *)cfp && (VALUE *)cfp < end) {
 	return FALSE;
     }
@@ -103,6 +105,8 @@ VM_EP_IN_HEAP_P(const rb_thread_t *th, const VALUE *ep)
 {
     const VALUE *start = th->ec.stack;
     const VALUE *end = (VALUE *)th->ec.cfp;
+    VM_ASSERT(start != NULL);
+
     if (start <= ep && ep < end) {
 	return FALSE;
     }
-- 
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