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Diffstat (limited to 'nptl/sysdeps/pthread/pthread_rwlock_timedwrlock.c')
-rw-r--r--nptl/sysdeps/pthread/pthread_rwlock_timedwrlock.c123
1 files changed, 123 insertions, 0 deletions
diff --git a/nptl/sysdeps/pthread/pthread_rwlock_timedwrlock.c b/nptl/sysdeps/pthread/pthread_rwlock_timedwrlock.c
new file mode 100644
index 0000000000..4c0dc38348
--- /dev/null
+++ b/nptl/sysdeps/pthread/pthread_rwlock_timedwrlock.c
@@ -0,0 +1,123 @@
+/* Copyright (C) 2003 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ 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. */
+
+#include <errno.h>
+#include <sysdep.h>
+#include <lowlevellock.h>
+#include <pthread.h>
+#include <pthreadP.h>
+
+
+/* Try to acquire write lock for RWLOCK or return after specfied time. */
+int
+pthread_rwlock_timedwrlock (rwlock, abstime)
+ pthread_rwlock_t *rwlock;
+ const struct timespec *abstime;
+{
+ int result = 0;
+
+ /* Make sure we are along. */
+ lll_mutex_lock (rwlock->__data.__lock);
+
+ while (1)
+ {
+ /* Get the rwlock if there is no writer and no reader. */
+ if (rwlock->__data.__writer == 0 && rwlock->__data.__nr_readers == 0)
+ {
+ /* Mark self as writer. */
+ rwlock->__data.__writer = (pthread_t) THREAD_SELF;
+ break;
+ }
+
+ /* Make sure we are not holding the rwlock as a writer. This is
+ a deadlock situation we recognize and report. */
+ if (rwlock->__data.__writer != 0
+ && __builtin_expect (rwlock->__data.__writer
+ == (pthread_t) THREAD_SELF, 0))
+ {
+ result = EDEADLK;
+ break;
+ }
+
+ /* Make sure the passed in timeout value is valid. Ideally this
+ test would be executed once. But since it must not be
+ performed if we would not block at all simply moving the test
+ to the front is no option. Replicating all the code is
+ costly while this test is not. */
+ if (abstime->tv_nsec >= 1000000000)
+ {
+ result = EINVAL;
+ break;
+ }
+
+ /* Get the current time. So far we support only one clock. */
+ struct timeval tv;
+ (void) gettimeofday (&tv, NULL);
+
+ /* Convert the absolute timeout value to a relative timeout. */
+ struct timespec rt;
+ rt.tv_sec = abstime->tv_sec - tv.tv_sec;
+ rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
+ if (rt.tv_nsec < 0)
+ {
+ rt.tv_nsec += 1000000000;
+ --rt.tv_sec;
+ }
+ /* Did we already time out? */
+ if (rt.tv_sec < 0)
+ {
+ result = ETIMEDOUT;
+ break;
+ }
+
+ /* Remember that we are a writer. */
+ if (++rwlock->__data.__nr_writers_queued == 0)
+ {
+ /* Overflow on number of queued writers. */
+ --rwlock->__data.__nr_writers_queued;
+ result = EAGAIN;
+ break;
+ }
+
+ /* Free the lock. */
+ lll_mutex_unlock (rwlock->__data.__lock);
+
+ /* Wait for the writer or reader(s) to finish. */
+ result = lll_futex_timed_wait (&rwlock->__data.__writer_wakeup, 0, &rt);
+
+ /* Get the lock. */
+ lll_mutex_lock (rwlock->__data.__lock);
+
+ /* To start over again, remove the thread from the writer list. */
+ --rwlock->__data.__nr_writers_queued;
+ rwlock->__data.__writer_wakeup = 0;
+
+ /* Did the futex call time out? */
+ if (result == -ETIMEDOUT)
+ {
+ result = ETIMEDOUT;
+ break;
+ }
+ }
+
+ /* We are done, free the lock. */
+ lll_mutex_unlock (rwlock->__data.__lock);
+
+ return result;
+}