thread_pthread.c: fix for dynamic PTHREAD_STACK_MIN

* thread_pthread.c (rb_thread_create_timer_thread): fix for platforms
  where PTHREAD_STACK_MIN is a dynamic value and not a compile-time
  constant.  [ruby-dev:47911] [Bug #9436]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44675 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Tue Jan 21 20:14:55 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* thread_pthread.c (rb_thread_create_timer_thread): fix for platforms
+	  where PTHREAD_STACK_MIN is a dynamic value and not a compile-time
+	  constant.  [ruby-dev:47911] [Bug #9436]
+
 Tue Jan 21 17:55:09 2014  Zachary Scott  <e@zzak.io>
 
 	* lib/uri/common.rb: [DOC] Use static w3.org uri [ci skip]

thread_pthread.c

@@ -1480,17 +1480,15 @@ rb_thread_create_timer_thread(void)
         }
 # ifdef PTHREAD_STACK_MIN
 	{
-#   define TIMER_THREAD_STACK_MIN_SIZE (4096 * 4)
+	    const size_t min_size = (4096 * 4);
 	    /* Allocate the machine stack for the timer thread
 	     * at least 16KB (4 pages).  FreeBSD 8.2 AMD64 causes
 	     * machine stack overflow only with PTHREAD_STACK_MIN.
 	     */
-#   if TIMER_THREAD_STACK_MIN_SIZE < PTHREAD_STACK_MIN
-#     undef TIMER_THREAD_STACK_MIN_SIZE
-#     define TIMER_THREAD_STACK_MIN_SIZE PTHREAD_STACK_MIN
-#   endif
-	    pthread_attr_setstacksize(&attr,
-				      TIMER_THREAD_STACK_MIN_SIZE + (THREAD_DEBUG ? BUFSIZ : 0));
+	    size_t stack_size = PTHREAD_STACK_MIN; /* may be dynamic, get only once */
+	    if (stack_size < min_size) stack_size = min_size;
+	    if (THREAD_DEBUG) stack_size += BUFSIZ;
+	    pthread_attr_setstacksize(&attr, stack_size);
 	}
 # endif
 #endif