* init.c: Make it compile with older kernel headers.

	* tst-initializers1.c: Show through exit code which test failed.

	* pthread_rwlock_init.c: Also initialize __shared field.
	* sysdeps/unix/sysv/linux/i386/bits/pthreadtypes.h: Split __flags
	element in rwlock structure into four byte elements.  One of them is
	the new __shared element.
	* sysdeps/unix/sysv/linux/x86_64/bits/pthreadtypes.h [__WORDSIZE=32]:
	Likewise.
	[__WORDSIZE=64]: Renamed __pad1 element int rwlock structire to
	__shared, adjust names of other padding elements.
	* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h: Likewise.
	* sysdeps/pthread/pthread.h: Adjust rwlock initializers.
	* sysdeps/unix/sysv/linux/lowlevelrwlock.sym: Add PSHARED.
	* sysdeps/unix/sysv/linux/powerpc/lowlevellock.h: Define
	FUTEX_PRIVATE_FLAG.
	* sysdeps/unix/sysv/linux/x86_64/pthread_rwlock_rdlock.S: Change main
	futex to use private operations if possible.
	* sysdeps/unix/sysv/linux/x86_64/pthread_rwlock_timedrdlock.S:
	Likewise.
	* sysdeps/unix/sysv/linux/x86_64/pthread_rwlock_timedwrlock.S:
	Likewise.
	* sysdeps/unix/sysv/linux/x86_64/pthread_rwlock_unlock.S: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/pthread_rwlock_wrlock.S: Likewise.

1 files changed, 35 insertions, 4 deletions

diff --git a/nptl/pthread_rwlock_init.c b/nptl/pthread_rwlock_init.c
index f664dd8104..27f25ac2ab 100644
--- a/nptl/pthread_rwlock_init.c
+++ b/nptl/pthread_rwlock_init.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2002 Free Software Foundation, Inc.
+/* Copyright (C) 2002, 2007 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
 
@@ -18,6 +18,7 @@
    02111-1307 USA.  */
 
 #include "pthreadP.h"
+#include <kernel-features.h>
 
 
 static const struct pthread_rwlockattr default_attr =
@@ -37,14 +38,44 @@ __pthread_rwlock_init (rwlock, attr)
   iattr = ((const struct pthread_rwlockattr *) attr) ?: &default_attr;
 
   rwlock->__data.__lock = 0;
-  rwlock->__data.__flags
-    = iattr->lockkind == PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP;
   rwlock->__data.__nr_readers = 0;
-  rwlock->__data.__writer = 0;
   rwlock->__data.__readers_wakeup = 0;
   rwlock->__data.__writer_wakeup = 0;
   rwlock->__data.__nr_readers_queued = 0;
   rwlock->__data.__nr_writers_queued = 0;
+  rwlock->__data.__writer = 0;
+
+  rwlock->__data.__flags
+    = iattr->lockkind == PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP;
+
+  /* The __SHARED field is computed to minimize the work that needs to
+     be done while handling the futex.  There are two inputs: the
+     availability of private futexes and whether the rwlock is shared
+     or private.  Unfortunately the value of a private rwlock is
+     fixed: it must be zero.  The PRIVATE_FUTEX flag has the value
+     0x80 in case private futexes are available and zero otherwise.
+     This leads to the following table:
+
+                 |     pshared     |     result
+                 | shared  private | shared  private |
+     ------------+-----------------+-----------------+
+     !avail 0    |     0       0   |     0       0   |
+      avail 0x80 |  0x80       0   |     0    0x80   |
+
+     If the pshared value is in locking functions XORed with avail
+     we get the expected result.  */
+#ifdef __ASSUME_PRIVATE_FUTEX
+  rwlock->__data.__shared = (iattr->pshared == PTHREAD_PROCESS_PRIVATE
+			     ? 0 : FUTEX_PRIVATE_FLAG);
+#else
+  rwlock->__data.__shared = (iattr->pshared == PTHREAD_PROCESS_PRIVATE
+			     ? 0
+			     : THREAD_GETMEM (THREAD_SELF,
+					      header.private_futex));
+#endif
+
+  rwlock->__data.__pad1 = 0;
+  rwlock->__data.__pad2 = 0;
 
   return 0;
 }