Maximum stacksize for user-defined threads necessary?

[Wolfram Gloger <Wolfram dot Gloger at dent dot med dot uni-muenchen dot de>]

Hi,

Is there any reason why we restrict the maximum size for user-defined
stacks in LinuxThreads?  I couldn't see one..

2002-09-09  Wolfram Gloger  <wg@malloc.de>

	* attr.c (__pthread_attr_setstack): Don't restrict maximum
	stacksize.
	* Examples/ex17.c (main): Try a really large user-defined stack
	first, then a smaller one if not enough memory.

--- attr.c.orig	Sun Feb 24 03:27:18 2002
+++ attr.c	Mon Sep  9 16:42:24 2002
@@ -221,24 +221,20 @@
 int __pthread_attr_setstack (pthread_attr_t *attr, void *stackaddr,
 			     size_t stacksize)
 {
-  int err;
-
   if ((((uintptr_t) stackaddr)
-       & (__alignof__ (struct _pthread_descr_struct) - 1)) != 0)
-    err = EINVAL;
-  else
-    err = __pthread_attr_setstacksize (attr, stacksize);
-  if (err == 0)
-    {
+       & (__alignof__ (struct _pthread_descr_struct) - 1)) != 0 ||
+      stacksize < PTHREAD_STACK_MIN)
+    return EINVAL;
+
+  attr->__stacksize = stacksize;
 #ifndef _STACK_GROWS_UP
-      attr->__stackaddr = (char *) stackaddr + stacksize;
+  attr->__stackaddr = (char *) stackaddr + stacksize;
 #else
-      attr->__stackaddr = stackaddr;
+  attr->__stackaddr = stackaddr;
 #endif
-      attr->__stackaddr_set = 1;
-    }
+  attr->__stackaddr_set = 1;
 
-  return err;
+  return 0;
 }
 weak_alias (__pthread_attr_setstack, pthread_attr_setstack)
 
--- Examples/ex17.c.orig	Sun Aug 25 10:38:22 2002
+++ Examples/ex17.c	Mon Sep  9 16:55:58 2002
@@ -15,7 +15,10 @@
   return NULL;
 }
 
-#define STACKSIZE 0x100000
+/* Try a really large stack first.  */
+#define STACKSIZE0 0x1000000
+/* Fallback if not enough memory.  */
+#define STACKSIZE1 0x100000
 
 int
 main (void)
@@ -24,20 +27,27 @@
   pthread_attr_t attr;
   int status;
   void *stack, *stack2;
-  size_t stacksize;
+  size_t set_stacksize = STACKSIZE0, stacksize;
 
   pthread_attr_init (&attr);
-  stack = mmap (NULL, STACKSIZE,
+  stack = mmap (NULL, set_stacksize,
 		PROT_READ | PROT_WRITE | PROT_EXEC,
 		MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 
   if (stack == MAP_FAILED)
     {
-      perror ("mmap failed");
-      return 1;
+      set_stacksize = STACKSIZE1;
+      stack = mmap (NULL, set_stacksize,
+		    PROT_READ | PROT_WRITE | PROT_EXEC,
+		    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+      if (stack == MAP_FAILED)
+	{
+	  perror ("mmap failed");
+	  return 1;
+	}
     }
 
-  status = pthread_attr_setstack (&attr, stack, STACKSIZE);
+  status = pthread_attr_setstack (&attr, stack, set_stacksize);
   if (status != 0)
     {
       printf ("pthread_attr_setstack failed: %s\n", strerror (status));
@@ -51,11 +61,11 @@
       return 1;
     }
 
-  if (stack2 != stack || stacksize != STACKSIZE)
+  if (stack2 != stack || stacksize != set_stacksize)
     {
       printf ("first pthread_attr_getstack returned different stack (%p,%zx)\n"
 	      "than was set by setstack (%p,%x)\n",
-	      stack2, stacksize, stack, STACKSIZE);
+	      stack2, stacksize, stack, set_stacksize);
       return 2;
     }
 
@@ -87,11 +97,11 @@
       return 1;
     }
 
-  if (stack2 != stack || stacksize != STACKSIZE)
+  if (stack2 != stack || stacksize != set_stacksize)
     {
       printf ("second pthread_attr_getstack returned different stack (%p,%zx)\n"
 	      "than was set by setstack (%p,%x)\n",
-	      stack2, stacksize, stack, STACKSIZE);
+	      stack2, stacksize, stack, set_stacksize);
       return 3;
     }