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Diffstat (limited to 'include/spl/sys/mutex.h')
| -rw-r--r-- | include/spl/sys/mutex.h | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/include/spl/sys/mutex.h b/include/spl/sys/mutex.h new file mode 100644 index 000000000..f906d49d4 --- /dev/null +++ b/include/spl/sys/mutex.h @@ -0,0 +1,184 @@ +/* + * 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://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/>. + */ + +#ifndef _SPL_MUTEX_H +#define _SPL_MUTEX_H + +#include <sys/types.h> +#include <linux/mutex.h> +#include <linux/lockdep.h> + +typedef enum { + MUTEX_DEFAULT = 0, + MUTEX_SPIN = 1, + MUTEX_ADAPTIVE = 2, + MUTEX_NOLOCKDEP = 3 +} kmutex_type_t; + +typedef struct { + struct mutex m_mutex; + spinlock_t m_lock; /* used for serializing mutex_exit */ + kthread_t *m_owner; +#ifdef CONFIG_LOCKDEP + kmutex_type_t m_type; +#endif /* CONFIG_LOCKDEP */ +} kmutex_t; + +#define MUTEX(mp) (&((mp)->m_mutex)) + +static inline void +spl_mutex_set_owner(kmutex_t *mp) +{ + mp->m_owner = current; +} + +static inline void +spl_mutex_clear_owner(kmutex_t *mp) +{ + mp->m_owner = NULL; +} + +#define mutex_owner(mp) (ACCESS_ONCE((mp)->m_owner)) +#define mutex_owned(mp) (mutex_owner(mp) == current) +#define MUTEX_HELD(mp) mutex_owned(mp) +#define MUTEX_NOT_HELD(mp) (!MUTEX_HELD(mp)) + +#ifdef CONFIG_LOCKDEP +static inline void +spl_mutex_set_type(kmutex_t *mp, kmutex_type_t type) +{ + mp->m_type = type; +} +static inline void +spl_mutex_lockdep_off_maybe(kmutex_t *mp) \ +{ \ + if (mp && mp->m_type == MUTEX_NOLOCKDEP) \ + lockdep_off(); \ +} +static inline void +spl_mutex_lockdep_on_maybe(kmutex_t *mp) \ +{ \ + if (mp && mp->m_type == MUTEX_NOLOCKDEP) \ + lockdep_on(); \ +} +#else /* CONFIG_LOCKDEP */ +#define spl_mutex_set_type(mp, type) +#define spl_mutex_lockdep_off_maybe(mp) +#define spl_mutex_lockdep_on_maybe(mp) +#endif /* CONFIG_LOCKDEP */ + +/* + * The following functions must be a #define and not static inline. + * This ensures that the native linux mutex functions (lock/unlock) + * will be correctly located in the users code which is important + * for the built in kernel lock analysis tools + */ +#undef mutex_init +#define mutex_init(mp, name, type, ibc) \ +{ \ + static struct lock_class_key __key; \ + ASSERT(type == MUTEX_DEFAULT || type == MUTEX_NOLOCKDEP); \ + \ + __mutex_init(MUTEX(mp), (name) ? (#name) : (#mp), &__key); \ + spin_lock_init(&(mp)->m_lock); \ + spl_mutex_clear_owner(mp); \ + spl_mutex_set_type(mp, type); \ +} + +#undef mutex_destroy +#define mutex_destroy(mp) \ +{ \ + VERIFY3P(mutex_owner(mp), ==, NULL); \ +} + +/* BEGIN CSTYLED */ +#define mutex_tryenter(mp) \ +({ \ + int _rc_; \ + \ + spl_mutex_lockdep_off_maybe(mp); \ + if ((_rc_ = mutex_trylock(MUTEX(mp))) == 1) \ + spl_mutex_set_owner(mp); \ + spl_mutex_lockdep_on_maybe(mp); \ + \ + _rc_; \ +}) +/* END CSTYLED */ + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +#define mutex_enter_nested(mp, subclass) \ +{ \ + ASSERT3P(mutex_owner(mp), !=, current); \ + spl_mutex_lockdep_off_maybe(mp); \ + mutex_lock_nested(MUTEX(mp), (subclass)); \ + spl_mutex_lockdep_on_maybe(mp); \ + spl_mutex_set_owner(mp); \ +} +#else /* CONFIG_DEBUG_LOCK_ALLOC */ +#define mutex_enter_nested(mp, subclass) \ +{ \ + ASSERT3P(mutex_owner(mp), !=, current); \ + spl_mutex_lockdep_off_maybe(mp); \ + mutex_lock(MUTEX(mp)); \ + spl_mutex_lockdep_on_maybe(mp); \ + spl_mutex_set_owner(mp); \ +} +#endif /* CONFIG_DEBUG_LOCK_ALLOC */ + +#define mutex_enter(mp) mutex_enter_nested((mp), 0) + +/* + * The reason for the spinlock: + * + * The Linux mutex is designed with a fast-path/slow-path design such that it + * does not guarantee serialization upon itself, allowing a race where latter + * acquirers finish mutex_unlock before former ones. + * + * The race renders it unsafe to be used for serializing the freeing of an + * object in which the mutex is embedded, where the latter acquirer could go + * on to free the object while the former one is still doing mutex_unlock and + * causing memory corruption. + * + * However, there are many places in ZFS where the mutex is used for + * serializing object freeing, and the code is shared among other OSes without + * this issue. Thus, we need the spinlock to force the serialization on + * mutex_exit(). + * + * See http://lwn.net/Articles/575477/ for the information about the race. + */ +#define mutex_exit(mp) \ +{ \ + spl_mutex_clear_owner(mp); \ + spin_lock(&(mp)->m_lock); \ + spl_mutex_lockdep_off_maybe(mp); \ + mutex_unlock(MUTEX(mp)); \ + spl_mutex_lockdep_on_maybe(mp); \ + spin_unlock(&(mp)->m_lock); \ + /* NOTE: do not dereference mp after this point */ \ +} + +int spl_mutex_init(void); +void spl_mutex_fini(void); + +#endif /* _SPL_MUTEX_H */ |