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Diffstat (limited to 'include/linux/rwsem_compat.h')
| -rw-r--r-- | include/linux/rwsem_compat.h | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/include/linux/rwsem_compat.h b/include/linux/rwsem_compat.h new file mode 100644 index 000000000..67a82bb44 --- /dev/null +++ b/include/linux/rwsem_compat.h @@ -0,0 +1,63 @@ +/*****************************************************************************\ + * 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 <[email protected]>. + * UCRL-CODE-235197 + * + * This file is part of the SPL, Solaris Porting Layer. + * For details, see <http://github.com/behlendorf/spl/>. + * + * 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/>. +\*****************************************************************************/ + +#ifndef _SPL_RWSEM_COMPAT_H +#define _SPL_RWSEM_COMPAT_H + +#include <linux/rwsem.h> + +#ifdef RWSEM_IS_LOCKED_TAKES_WAIT_LOCK +/* + * A race condition in rwsem_is_locked() was fixed in Linux 2.6.33 and the fix + * was backported to RHEL5 as of kernel 2.6.18-190.el5. Details can be found + * here: + * + * https://bugzilla.redhat.com/show_bug.cgi?id=526092 + + * The race condition was fixed in the kernel by acquiring the semaphore's + * wait_lock inside rwsem_is_locked(). The SPL worked around the race + * condition by acquiring the wait_lock before calling that function, but + * with the fix in place we must not do that. + */ + +#define spl_rwsem_is_locked(rwsem) \ +({ \ + rwsem_is_locked(rwsem); \ +}) + +#else + +#define spl_rwsem_is_locked(rwsem) \ +({ \ + unsigned long _flags_; \ + int _rc_; \ + spin_lock_irqsave(&rwsem->wait_lock, _flags_); \ + _rc_ = rwsem_is_locked(rwsem); \ + spin_unlock_irqrestore(&rwsem->wait_lock, _flags_); \ + _rc_; \ +}) + +#endif /* RWSEM_IS_LOCKED_TAKES_WAIT_LOCK */ + +#endif /* _SPL_RWSEM_COMPAT_H */ |