/*****************************************************************************\ * 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 . * UCRL-CODE-235197 * * This file is part of the SPL, Solaris Porting Layer. * For details, see . * * 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 . \*****************************************************************************/ #ifndef _SPL_MUTEX_H #define _SPL_MUTEX_H #include #include #include typedef enum { MUTEX_DEFAULT = 0, MUTEX_SPIN = 1, MUTEX_ADAPTIVE = 2 } kmutex_type_t; #if defined(HAVE_MUTEX_OWNER) && defined(CONFIG_SMP) && !defined(CONFIG_DEBUG_MUTEXES) /* * We define a 1-field struct rather than a straight typedef to enforce type * safety. */ typedef struct { struct mutex m; } kmutex_t; static inline kthread_t * mutex_owner(kmutex_t *mp) { #if defined(HAVE_MUTEX_OWNER_TASK_STRUCT) return ACCESS_ONCE(mp->m.owner); #else struct thread_info *owner = ACCESS_ONCE(mp->m.owner); if (owner) return owner->task; return NULL; #endif } #define mutex_owned(mp) (mutex_owner(mp) == current) #define MUTEX_HELD(mp) mutex_owned(mp) #define MUTEX_NOT_HELD(mp) (!MUTEX_HELD(mp)) #undef mutex_init #define mutex_init(mp, name, type, ibc) \ ({ \ static struct lock_class_key __key; \ ASSERT(type == MUTEX_DEFAULT); \ \ __mutex_init(&(mp)->m, #mp, &__key); \ }) #undef mutex_destroy #define mutex_destroy(mp) \ ({ \ VERIFY3P(mutex_owner(mp), ==, NULL); \ }) #define mutex_tryenter(mp) mutex_trylock(&(mp)->m) #define mutex_enter(mp) \ ({ \ ASSERT3P(mutex_owner(mp), !=, current); \ mutex_lock(&(mp)->m); \ }) #define mutex_exit(mp) mutex_unlock(&(mp)->m) #ifdef HAVE_GPL_ONLY_SYMBOLS # define mutex_enter_nested(mp, sc) mutex_lock_nested(&(mp)->m, sc) #else # define mutex_enter_nested(mp, sc) mutex_enter(mp) #endif /* HAVE_GPL_ONLY_SYMBOLS */ #else /* HAVE_MUTEX_OWNER */ typedef struct { struct mutex m_mutex; kthread_t *m_owner; } kmutex_t; #ifdef HAVE_TASK_CURR extern int spl_mutex_spin_max(void); #else /* HAVE_TASK_CURR */ # define task_curr(owner) 0 # define spl_mutex_spin_max() 0 #endif /* HAVE_TASK_CURR */ #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)) /* * 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); \ \ __mutex_init(MUTEX(mp), #mp, &__key); \ spl_mutex_clear_owner(mp); \ }) #undef mutex_destroy #define mutex_destroy(mp) \ ({ \ VERIFY3P(mutex_owner(mp), ==, NULL); \ }) #define mutex_tryenter(mp) \ ({ \ int _rc_; \ \ if ((_rc_ = mutex_trylock(MUTEX(mp))) == 1) \ spl_mutex_set_owner(mp); \ \ _rc_; \ }) /* * Adaptive mutexs assume that the lock may be held by a task running * on a different cpu. The expectation is that the task will drop the * lock before leaving the head of the run queue. So the ideal thing * to do is spin until we acquire the lock and avoid a context switch. * However it is also possible the task holding the lock yields the * processor with out dropping lock. In this case, we know it's going * to be a while so we stop spinning and go to sleep waiting for the * lock to be available. This should strike the optimum balance * between spinning and sleeping waiting for a lock. */ #define mutex_enter(mp) \ ({ \ kthread_t *_owner_; \ int _rc_, _count_; \ \ _rc_ = 0; \ _count_ = 0; \ _owner_ = mutex_owner(mp); \ ASSERT3P(_owner_, !=, current); \ \ while (_owner_ && task_curr(_owner_) && \ _count_ <= spl_mutex_spin_max()) { \ if ((_rc_ = mutex_trylock(MUTEX(mp)))) \ break; \ \ _count_++; \ } \ \ if (!_rc_) \ mutex_lock(MUTEX(mp)); \ \ spl_mutex_set_owner(mp); \ }) #define mutex_exit(mp) \ ({ \ spl_mutex_clear_owner(mp); \ mutex_unlock(MUTEX(mp)); \ }) #ifdef HAVE_GPL_ONLY_SYMBOLS # define mutex_enter_nested(mp, sc) \ ({ \ mutex_lock_nested(MUTEX(mp), sc); \ spl_mutex_set_owner(mp); \ }) #else # define mutex_enter_nested(mp, sc) \ ({ \ mutex_enter(mp); \ }) #endif #endif /* HAVE_MUTEX_OWNER */ int spl_mutex_init(void); void spl_mutex_fini(void); #endif /* _SPL_MUTEX_H */