+/*
+ * 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
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include <linux/module.h>
-#include <linux/hardirq.h>
#include <sys/types.h>
-#include <sys/kmem.h>
-
-#define MUTEX_DEFAULT 0
-#define MUTEX_SPIN 1
-#define MUTEX_ADAPTIVE 2
+#include <linux/mutex.h>
+#include <linux/compiler_compat.h>
+#include <linux/lockdep.h>
-#define MUTEX_ENTER_TOTAL 0
-#define MUTEX_ENTER_NOT_HELD 1
-#define MUTEX_ENTER_SPIN 2
-#define MUTEX_ENTER_SLEEP 3
-#define MUTEX_TRYENTER_TOTAL 4
-#define MUTEX_TRYENTER_NOT_HELD 5
-#define MUTEX_STATS_SIZE 6
-
-#define KM_MAGIC 0x42424242
-#define KM_POISON 0x84
+typedef enum {
+ MUTEX_DEFAULT = 0,
+ MUTEX_SPIN = 1,
+ MUTEX_ADAPTIVE = 2,
+ MUTEX_NOLOCKDEP = 3
+} kmutex_type_t;
typedef struct {
- int32_t km_magic;
- int16_t km_type;
- int16_t km_name_size;
- char *km_name;
- struct task_struct *km_owner;
- struct semaphore *km_sem;
-#ifdef DEBUG_MUTEX
- int *km_stats;
- struct list_head km_list;
-#endif
+ struct mutex m_mutex;
+ spinlock_t m_lock; /* used for serializing mutex_exit */
+ /* only when kernel doesn't have owner */
+ kthread_t *m_owner;
+#ifdef CONFIG_LOCKDEP
+ kmutex_type_t m_type;
+#endif /* CONFIG_LOCKDEP */
} kmutex_t;
-extern int mutex_spin_max;
+#define MUTEX(mp) (&((mp)->m_mutex))
-#ifdef DEBUG_MUTEX
-extern int mutex_stats[MUTEX_STATS_SIZE];
-extern spinlock_t mutex_stats_lock;
-extern struct list_head mutex_stats_list;
-#define MUTEX_STAT_INC(stats, stat) ((stats)[stat]++)
-#else
-#define MUTEX_STAT_INC(stats, stat)
-#endif
+static inline void
+spl_mutex_set_owner(kmutex_t *mp)
+{
+ /*
+ * kernel will handle its owner, so we don't need to do anything if it
+ * is defined.
+ */
+ mp->m_owner = current;
+}
-int spl_mutex_init(void);
-void spl_mutex_fini(void);
+static inline void
+spl_mutex_clear_owner(kmutex_t *mp)
+{
+ mp->m_owner = NULL;
+}
+
+#define mutex_owner(mp) (ACCESS_ONCE(MUTEX(mp)->owner))
+#define mutex_owned(mp) (mutex_owner(mp) == current)
+#define MUTEX_HELD(mp) mutex_owned(mp)
+#define MUTEX_NOT_HELD(mp) (!MUTEX_HELD(mp))
-extern void __spl_mutex_init(kmutex_t *mp, char *name, int type, void *ibc);
-extern void __spl_mutex_destroy(kmutex_t *mp);
-extern int __mutex_tryenter(kmutex_t *mp);
-extern void __mutex_enter(kmutex_t *mp);
-extern void __mutex_exit(kmutex_t *mp);
-extern int __mutex_owned(kmutex_t *mp);
-extern kthread_t *__spl_mutex_owner(kmutex_t *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); \
+}
-#define mutex_init(mp, name, type, ibc) \
-({ \
- if ((name) == NULL) \
- __spl_mutex_init(mp, #mp, type, ibc); \
- else \
- __spl_mutex_init(mp, name, type, ibc); \
+#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_; \
})
-#define mutex_destroy(mp) __spl_mutex_destroy(mp)
-#define mutex_tryenter(mp) __mutex_tryenter(mp)
-#define mutex_enter(mp) __mutex_enter(mp)
-#define mutex_exit(mp) __mutex_exit(mp)
-#define mutex_owned(mp) __mutex_owned(mp)
-#define mutex_owner(mp) __spl_mutex_owner(mp)
-#define MUTEX_HELD(mp) mutex_owned(mp)
-
-#ifdef __cplusplus
+
+#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
+#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_lockdep_off_maybe(mp); \
+ spin_lock(&(mp)->m_lock); \
+ spl_mutex_clear_owner(mp); \
+ mutex_unlock(MUTEX(mp)); \
+ spin_unlock(&(mp)->m_lock); \
+ spl_mutex_lockdep_on_maybe(mp); \
+}
+
+int spl_mutex_init(void);
+void spl_mutex_fini(void);
-#endif /* _SPL_MUTEX_H */
+#endif /* _SPL_MUTEX_H */
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