| /* |
| * 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/>. |
| */ |
| |
| #ifndef _SPL_MUTEX_H |
| #define _SPL_MUTEX_H |
| |
| #include <sys/types.h> |
| #include <linux/sched.h> |
| #include <linux/mutex.h> |
| #include <linux/lockdep.h> |
| #include <linux/compiler_compat.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) (READ_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 */ |
| |
| #define NESTED_SINGLE 1 |
| |
| #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 */ \ |
| } |
| |
| #endif /* _SPL_MUTEX_H */ |