merge revision(s) r46495,r46499: [Backport #9971]

	signal.c: no cfunc frame at stack overflow

	* signal.c (check_stack_overflow): avoid pushing a cfunc frame,
  trying to fix stack overflow deadlock.
	* signal.c (check_stack_overflow): drop the last tag too close to
	  the fault page, to get rid of stack overflow deadlock.
	  [Bug #9971]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@47597 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 9 insertions, 2 deletions

diff --git a/signal.c b/signal.c
index 1524885eb5..82fad956df 100644
--- a/signal.c
+++ b/signal.c
@@ -711,7 +711,14 @@ check_stack_overflow(const uintptr_t addr, const ucontext_t *ctx)
     /* SP in ucontext is not decremented yet when `push` failed, so
      * the fault page can be the next. */
     if (sp_page == fault_page || sp_page == fault_page + 1) {
-	ruby_thread_stack_overflow(GET_THREAD());
+	rb_thread_t *th = ruby_current_thread;
+	if ((uintptr_t)th->tag->buf / pagesize == sp_page) {
+	    /* drop the last tag if it is close to the fault,
+	     * otherwise it can cause stack overflow again at the same
+	     * place. */
+	    th->tag = th->tag->prev;
+	}
+	ruby_thread_stack_overflow(th);
     }
 }
 #else
@@ -719,7 +726,7 @@ static void
 check_stack_overflow(const void *addr)
 {
     int ruby_stack_overflowed_p(const rb_thread_t *, const void *);
-    rb_thread_t *th = GET_THREAD();
+    rb_thread_t *th = ruby_current_thread;
     if (ruby_stack_overflowed_p(th, addr)) {
 	ruby_thread_stack_overflow(th);
     }