UBUNTU: SAUCE: (noup) Update spl to 0.6.5.9-1, zfs to 0.6.5.9-2

[mirror_ubuntu-bionic-kernel.git] / spl / module / spl / spl-rwlock.c

diff --git a/spl/module/spl/spl-rwlock.c b/spl/module/spl/spl-rwlock.c
new file mode 100644 (file)
index 0000000..77f46f2
--- /dev/null
+++ b/spl/module/spl/spl-rwlock.c
@@ -0,0 +1,86 @@
+/*****************************************************************************\
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL 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 General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *****************************************************************************
+ *  Solaris Porting Layer (SPL) Reader/Writer Lock Implementation.
+\*****************************************************************************/
+
+#include <sys/rwlock.h>
+
+#ifdef DEBUG_SUBSYSTEM
+#undef DEBUG_SUBSYSTEM
+#endif
+
+#define DEBUG_SUBSYSTEM S_RWLOCK
+
+#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
+static int
+__rwsem_tryupgrade(struct rw_semaphore *rwsem)
+{
+       int ret = 0;
+       unsigned long flags;
+       spl_rwsem_lock_irqsave(&rwsem->wait_lock, flags);
+       if (RWSEM_COUNT(rwsem) == SPL_RWSEM_SINGLE_READER_VALUE &&
+           list_empty(&rwsem->wait_list)) {
+               ret = 1;
+               RWSEM_COUNT(rwsem) = SPL_RWSEM_SINGLE_WRITER_VALUE;
+       }
+       spl_rwsem_unlock_irqrestore(&rwsem->wait_lock, flags);
+       return (ret);
+}
+#elif defined(HAVE_RWSEM_ATOMIC_LONG_COUNT)
+static int
+__rwsem_tryupgrade(struct rw_semaphore *rwsem)
+{
+       long val;
+       val = atomic_long_cmpxchg(&rwsem->count, SPL_RWSEM_SINGLE_READER_VALUE,
+           SPL_RWSEM_SINGLE_WRITER_VALUE);
+       return (val == SPL_RWSEM_SINGLE_READER_VALUE);
+}
+#else
+static int
+__rwsem_tryupgrade(struct rw_semaphore *rwsem)
+{
+       typeof (rwsem->count) val;
+       val = cmpxchg(&rwsem->count, SPL_RWSEM_SINGLE_READER_VALUE,
+           SPL_RWSEM_SINGLE_WRITER_VALUE);
+       return (val == SPL_RWSEM_SINGLE_READER_VALUE);
+}
+#endif
+
+int
+rwsem_tryupgrade(struct rw_semaphore *rwsem)
+{
+       if (__rwsem_tryupgrade(rwsem)) {
+               rwsem_release(&rwsem->dep_map, 1, _RET_IP_);
+               rwsem_acquire(&rwsem->dep_map, 0, 1, _RET_IP_);
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
+               rwsem->owner = current;
+#endif
+               return (1);
+       }
+       return (0);
+}
+EXPORT_SYMBOL(rwsem_tryupgrade);
+
+int spl_rw_init(void) { return 0; }
+void spl_rw_fini(void) { }