[BZ #2571]

	* nscd/nscd_helper.c (__nscd_get_map_ref): Make mapptr argument a
	volatile pointer so that the mapptr->mapped value is re-read after
	the lock is retrieved.
	* nscd/nscd-client.h: Update __nscd_get_map_ref prototype.

	* sysdeps/unix/sysv/linux/ia64/clone2.S: Check for NULL stack

ChangeLog

@@ -1,5 +1,11 @@
 2006-04-25  Ulrich Drepper  <drepper@redhat.com>
 
+	[BZ #2571]
+	* nscd/nscd_helper.c (__nscd_get_map_ref): Make mapptr argument a
+	volatile pointer so that the mapptr->mapped value is re-read after
+	the lock is retrieved.
+	* nscd/nscd-client.h: Update __nscd_get_map_ref prototype.
+
 	* include/features.h [_GNU_SOURCE] (_POSIX_C_SOURCE): Define to
 	200112L.
 
@@ -12,7 +18,7 @@
 	(struct hconf): Replace service related fields with placeholders.
 
 	[BZ #2386]
-	* sysdeps/unix/sysv/linux/ia64/clone2.S: Check for NULL stakc
+	* sysdeps/unix/sysv/linux/ia64/clone2.S: Check for NULL stack
 	pointers to match other architectures.
 	* sysdeps/unix/sysv/linux/Makefile [subdirs=misc] (tests): Add
 	tst-clone.

nscd/nscd-client.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 1998, 1999, 2000, 2003, 2004, 2005
+/* Copyright (c) 1998, 1999, 2000, 2003, 2004, 2005, 2006
    Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Thorsten Kukuk <kukuk@suse.de>, 1998.
@@ -277,7 +277,7 @@ extern int __nscd_open_socket (const char *key, size_t keylen,
 /* Get reference of mapping.  */
 extern struct mapped_database *__nscd_get_map_ref (request_type type,
 						   const char *name,
-						   struct locked_map_ptr *mapptr,
+						   volatile struct locked_map_ptr *mapptr,
 						   int *gc_cyclep);
 
 /* Unmap database.  */

nscd/nscd_helper.c

@@ -316,17 +316,18 @@ get_mapping (request_type type, const char *key,
 
 struct mapped_database *
 __nscd_get_map_ref (request_type type, const char *name,
-		    struct locked_map_ptr *mapptr, int *gc_cyclep)
+		    volatile struct locked_map_ptr *mapptr, int *gc_cyclep)
 {
   struct mapped_database *cur = mapptr->mapped;
   if (cur == NO_MAPPING)
     return cur;
 
   int cnt = 0;
-  while (atomic_compare_and_exchange_val_acq (&mapptr->lock, 1, 0) != 0)
+  while (__builtin_expect (atomic_compare_and_exchange_val_acq (&mapptr->lock,
+								1, 0) != 0, 0))
     {
       // XXX Best number of rounds?
-      if (++cnt > 5)
+      if (__builtin_expect (++cnt > 5, 0))
 	return NO_MAPPING;
 
       atomic_delay ();
@@ -340,7 +341,8 @@ __nscd_get_map_ref (request_type type, const char *name,
       if (cur == NULL
 	  || (cur->head->nscd_certainly_running == 0
 	      && cur->head->timestamp + MAPPING_TIMEOUT < time (NULL)))
-	cur = get_mapping (type, name, &mapptr->mapped);
+	cur = get_mapping (type, name,
+			   (struct mapped_database **) &mapptr->mapped);
 
       if (__builtin_expect (cur != NO_MAPPING, 1))
 	{