1 files changed, 98 insertions, 0 deletions
diff --git a/sysdeps/htl/pt-rwlock-unlock.c b/sysdeps/htl/pt-rwlock-unlock.c
new file mode 100644
index 0000000000..44b26d2b1c
--- /dev/null
+++ b/sysdeps/htl/pt-rwlock-unlock.c
@@ -0,0 +1,98 @@
+/* Unlock a rwlock.  Generic version.
+   Copyright (C) 2000-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <pthread.h>
+
+#include <pt-internal.h>
+
+/* Unlock *RWLOCK, rescheduling a waiting writer thread or, if there
+   are no threads waiting for a write lock, rescheduling the reader
+   threads.  */
+int
+__pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
+{
+  struct __pthread *wakeup;
+
+  __pthread_spin_lock (&rwlock->__lock);
+
+  assert (__pthread_spin_trylock (&rwlock->__held) == EBUSY);
+
+  if (rwlock->__readers > 1)
+    /* There are other readers.  */
+    {
+      rwlock->__readers--;
+      __pthread_spin_unlock (&rwlock->__lock);
+      return 0;
+    }
+
+  if (rwlock->__readers == 1)
+    /* Last reader.  */
+    rwlock->__readers = 0;
+
+
+  /* Wake someone else up.  Try the writer queue first, then the
+     reader queue if that is empty.  */
+
+  if (rwlock->__writerqueue)
+    {
+      wakeup = rwlock->__writerqueue;
+      __pthread_dequeue (wakeup);
+
+      /* We do not unlock RWLOCK->held: we are transferring the ownership
+         to the thread that we are waking up.  */
+
+      __pthread_spin_unlock (&rwlock->__lock);
+      __pthread_wakeup (wakeup);
+
+      return 0;
+    }
+
+  if (rwlock->__readerqueue)
+    {
+      unsigned n = 0;
+
+      __pthread_queue_iterate (rwlock->__readerqueue, wakeup)
+	n++;
+
+      {
+	struct __pthread *wakeups[n];
+	unsigned i = 0;
+
+	__pthread_dequeuing_iterate (rwlock->__readerqueue, wakeup)
+	  wakeups[i++] = wakeup;
+
+	rwlock->__readers += n;
+	rwlock->__readerqueue = 0;
+
+	__pthread_spin_unlock (&rwlock->__lock);
+
+	for (i = 0; i < n; i++)
+	  __pthread_wakeup (wakeups[i]);
+      }
+
+      return 0;
+    }
+
+
+  /* Noone is waiting.  Just unlock it.  */
+
+  __pthread_spin_unlock (&rwlock->__held);
+  __pthread_spin_unlock (&rwlock->__lock);
+  return 0;
+}
+weak_alias (__pthread_rwlock_unlock, pthread_rwlock_unlock);