nptl/tst-tls3-malloc: Force freeing of thread stacks

It turns out that due to the reduced stack size in tst-tls3 and the
(fixed) default stack cache size, allocated TLS variables are never
freed, so the test coverage for tst-tls3-malloc is less than complete.
This change increases the thread stack size for tst-tls3-malloc only,
to make sure thread stacks and TLS variables are freed.

ChangeLog

@@ -1,3 +1,10 @@
+2016-08-16  Florian Weimer  <fweimer@redhat.com>
+
+	* nptl/tst-tls3.c (default_stack_size_in_mb, stack_size_in_mb):
+	New.
+	(do_test): Apply default_stack_size_in_mb if not set.
+	* nptl/tst-tls3-malloc.c (stack_size_in_mb): Override default.
+
 2016-08-15  Andreas Schwab  <schwab@suse.de>
 
 	[BZ #20435]

nptl/tst-tls3-malloc.c

@@ -19,6 +19,11 @@
 /* Reuse the test.  */
 #include "tst-tls3.c"
 
+/* Increase the thread stack size to 10 MiB, so that some thread
+   stacks are actually freed.  (The stack cache size is currently
+   hard-wired to 40 MiB in allocatestack.c.)  */
+static long stack_size_in_mb = 10;
+
 #include <sys/mman.h>
 
 /* Interpose a minimal malloc implementation.  This implementation

nptl/tst-tls3.c

@@ -29,6 +29,11 @@
 
 #define THE_SIG SIGUSR1
 
+/* The stack size can be overriden.  With a sufficiently large stack
+   size, thread stacks for terminated threads are freed, but this does
+   not happen with the default size of 1 MiB.  */
+enum { default_stack_size_in_mb = 1 };
+static long stack_size_in_mb;
 
 #define N 10
 static pthread_t th[N];
@@ -72,6 +77,9 @@ int nsigs;
 int
 do_test (void)
 {
+  if (stack_size_in_mb == 0)
+    stack_size_in_mb = default_stack_size_in_mb;
+
   if ((uintptr_t) pthread_self () & (TCB_ALIGNMENT - 1))
     {
       puts ("initial thread's struct pthread not aligned enough");
@@ -127,7 +135,7 @@ do_test (void)
       exit (1);
     }
 
-  if (pthread_attr_setstacksize (&a, 1 * 1024 * 1024) != 0)
+  if (pthread_attr_setstacksize (&a, stack_size_in_mb * 1024 * 1024) != 0)
     {
       puts ("attr_setstacksize failed");
       return 1;