From c50afaa1c94c150222d684fbc7fc8b79aa62e0c2 Mon Sep 17 00:00:00 2001
From: ko1 <ko1@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Fri, 14 Apr 2017 07:46:11 +0000
Subject: [PATCH] disable rewind hooks.

* vm.c (hook_before_rewind): skip rewind hooks if err is SystemStackError
  because rewind hooks can cause stack overflow again and again.

* thread.c (ruby_thread_stack_overflow): do not disable all hooks.
  Additionally, clearing ruby_vm_event_flags is not suitable way
  to disable hooks.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58349 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 thread.c | 1 -
 vm.c     | 9 ++++++---
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/thread.c b/thread.c
index 54b4fd599c..a93c6100bf 100644
--- a/thread.c
+++ b/thread.c
@@ -2169,7 +2169,6 @@ NORETURN(void ruby_thread_stack_overflow(rb_thread_t *th));
 void
 ruby_thread_stack_overflow(rb_thread_t *th)
 {
-    ruby_vm_event_flags = 0;
     th->raised_flag = 0;
 #ifdef USE_SIGALTSTACK
     if (!rb_threadptr_during_gc(th)) {
diff --git a/vm.c b/vm.c
index 869d097d7c..e64c072fdc 100644
--- a/vm.c
+++ b/vm.c
@@ -1637,8 +1637,11 @@ frame_name(const rb_control_frame_t *cfp)
 #endif
 
 static void
-hook_before_rewind(rb_thread_t *th, const rb_control_frame_t *cfp, int will_finish_vm_exec, struct vm_throw_data *err)
+hook_before_rewind(rb_thread_t *th, const rb_control_frame_t *cfp, int will_finish_vm_exec, int state, struct vm_throw_data *err)
 {
+    if (state == TAG_RAISE && RBASIC_CLASS(err) == rb_eSysStackError) {
+	return;
+    }
     switch (VM_FRAME_TYPE(th->cfp)) {
       case VM_FRAME_MAGIC_METHOD:
 	RUBY_DTRACE_METHOD_RETURN_HOOK(th, 0, 0);
@@ -1829,7 +1832,7 @@ vm_exec(rb_thread_t *th)
 			    th->errinfo = Qnil;
 			    result = THROW_DATA_VAL(err);
 			    THROW_DATA_CATCH_FRAME_SET(err, cfp + 1);
-			    hook_before_rewind(th, th->cfp, TRUE, err);
+			    hook_before_rewind(th, th->cfp, TRUE, state, err);
 			    rb_vm_pop_frame(th);
 			    goto finish_vme;
 			}
@@ -1971,7 +1974,7 @@ vm_exec(rb_thread_t *th)
 	    goto vm_loop_start;
 	}
 	else {
-	    hook_before_rewind(th, th->cfp, FALSE, err);
+	    hook_before_rewind(th, th->cfp, FALSE, state, err);
 
 	    if (VM_FRAME_FINISHED_P(th->cfp)) {
 		rb_vm_pop_frame(th);