-/* Copyright (C) 2002,2007,2009,2011 Free Software Foundation, Inc.
+/* Copyright (C) 2002-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
- 02111-1307 USA. */
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
#include "pthreadP.h"
#include <string.h>
-#include <kernel-features.h>
-static const struct pthread_rwlockattr default_attr =
+static const struct pthread_rwlockattr default_rwlockattr =
{
.lockkind = PTHREAD_RWLOCK_DEFAULT_NP,
.pshared = PTHREAD_PROCESS_PRIVATE
};
+/* See pthread_rwlock_common.c. */
int
-__pthread_rwlock_init (rwlock, attr)
- pthread_rwlock_t *rwlock;
- const pthread_rwlockattr_t *attr;
+__pthread_rwlock_init (pthread_rwlock_t *rwlock,
+ const pthread_rwlockattr_t *attr)
{
+ ASSERT_TYPE_SIZE (pthread_rwlock_t, __SIZEOF_PTHREAD_RWLOCK_T);
+
const struct pthread_rwlockattr *iattr;
- iattr = ((const struct pthread_rwlockattr *) attr) ?: &default_attr;
+ iattr = ((const struct pthread_rwlockattr *) attr) ?: &default_rwlockattr;
memset (rwlock, '\0', sizeof (*rwlock));
- 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 |
+ rwlock->__data.__flags = iattr->lockkind;
- 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
+ /* The value of __SHARED in a private rwlock must be zero. */
+ rwlock->__data.__shared = (iattr->pshared != PTHREAD_PROCESS_PRIVATE);
return 0;
}