Fix race in qsort_r initialization.

1 files changed, 5 insertions, 1 deletions

diff --git a/stdlib/msort.c b/stdlib/msort.c
index 35cd4d0311..fc58f0d417 100644
--- a/stdlib/msort.c
+++ b/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);
 	}