Fix race in qsort_r initialization.

(cherry picked from commit fb88ac7)

ChangeLog

@@ -1,3 +1,9 @@
+2010-12-09  Ulrich Drepper  <drepper@gmail.com>
+
+	[BZ #11655]
+	* stdlib/msort.c (qsort_r): Make sure both phys_pages and pagesize
+	are initialized.
+
 2010-12-09  Jakub Jelinek  <jakub@redhat.com>
 
 	* string/bits/string3.h (memmove, bcopy): Remove __restrict.

stdlib/msort.c

@@ -25,6 +25,7 @@
 #include <unistd.h>
 #include <memcopy.h>
 #include <errno.h>
+#include <atomic.h>
 
 struct msort_param
 {
@@ -182,7 +183,7 @@ qsort_r (void *b, size_t n, size_t s, __compar_d_fn_t cmp, void *arg)
       static long int phys_pages;
       static int pagesize;
 
-      if (phys_pages == 0)
+      if (pagesize == 0)
 	{
 	  phys_pages = __sysconf (_SC_PHYS_PAGES);
 
@@ -197,6 +198,9 @@ qsort_r (void *b, size_t n, size_t s, __compar_d_fn_t cmp, void *arg)
 	     a quarter of the physical memory.  */
 	  phys_pages /= 4;
 
+	  /* Make sure phys_pages is written to memory.  */
+	  atomic_write_barrier ();
+
 	  pagesize = __sysconf (_SC_PAGESIZE);
 	}