-/*
- * This file is part of the SPL: Solaris Porting Layer.
- *
- * Copyright (c) 2009 Lawrence Livermore National Security, LLC.
- * Produced at Lawrence Livermore National Laboratory
- * Written by:
- * Brian Behlendorf <behlendorf1@llnl.gov>,
- * Herb Wartens <wartens2@llnl.gov>,
- * Jim Garlick <garlick@llnl.gov>
+/*****************************************************************************\
+ * 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 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.
+ * This file is part of the SPL, Solaris Porting Layer.
+ * For details, see <http://zfsonlinux.org/>.
*
- * This is distributed in the hope that it will be useful, but WITHOUT
+ * 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 this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
+ * with the SPL. If not, see <http://www.gnu.org/licenses/>.
+\*****************************************************************************/
#ifndef _SPL_RWLOCK_H
-#define _SPL_RWLOCK_H
+#define _SPL_RWLOCK_H
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/rwsem.h>
#include <sys/types.h>
+#include <linux/rwsem.h>
+#include <linux/rwsem_compat.h>
typedef enum {
- RW_DRIVER = 2,
- RW_DEFAULT = 4
+ RW_DRIVER = 2,
+ RW_DEFAULT = 4,
+ RW_NOLOCKDEP = 5
} krw_type_t;
typedef enum {
- RW_NONE = 0,
- RW_WRITER = 1,
- RW_READER = 2
+ RW_NONE = 0,
+ RW_WRITER = 1,
+ RW_READER = 2
} krw_t;
-typedef struct rw_semaphore krwlock_t;
+/*
+ * If CONFIG_RWSEM_SPIN_ON_OWNER is defined, rw_semaphore will have an owner
+ * field, so we don't need our own.
+ */
+typedef struct {
+ struct rw_semaphore rw_rwlock;
+#ifndef CONFIG_RWSEM_SPIN_ON_OWNER
+ kthread_t *rw_owner;
+#endif
+#ifdef CONFIG_LOCKDEP
+ krw_type_t rw_type;
+#endif /* CONFIG_LOCKDEP */
+} krwlock_t;
+
+#define SEM(rwp) (&(rwp)->rw_rwlock)
-#define rw_init(rwlp, name, type, arg) init_rwsem(rwlp)
-#define rw_destroy(rwlp) ((void)0)
-#define rw_downgrade(rwlp) downgrade_write(rwlp)
-#define RW_LOCK_HELD(rwlp) rwsem_is_locked(rwlp)
+static inline void
+spl_rw_set_owner(krwlock_t *rwp)
+{
/*
- * the rw-semaphore definition
- * - if activity/count is 0 then there are no active readers or writers
- * - if activity/count is +ve then that is the number of active readers
- * - if activity/count is -1 then there is one active writer
+ * If CONFIG_RWSEM_SPIN_ON_OWNER is defined, down_write, up_write,
+ * downgrade_write and __init_rwsem will set/clear owner for us.
*/
-#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
-# define RW_COUNT(rwlp) ((rwlp)->activity)
-# define RW_READ_HELD(rwlp) ((RW_COUNT(rwlp) > 0) ? RW_COUNT(rwlp) : 0)
-# define RW_WRITE_HELD(rwlp) ((RW_COUNT(rwlp) < 0))
-# define rw_exit_locked(rwlp) __up_read_locked(rwlp)
-# define rw_tryenter_locked(rwlp) __down_write_trylock_locked(rwlp)
-void __up_read_locked(struct rw_semaphore *);
-int __down_write_trylock_locked(struct rw_semaphore *);
+#ifndef CONFIG_RWSEM_SPIN_ON_OWNER
+ rwp->rw_owner = current;
+#endif
+}
+
+static inline void
+spl_rw_clear_owner(krwlock_t *rwp)
+{
+#ifndef CONFIG_RWSEM_SPIN_ON_OWNER
+ rwp->rw_owner = NULL;
+#endif
+}
+
+static inline kthread_t *
+rw_owner(krwlock_t *rwp)
+{
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
+ return (SEM(rwp)->owner);
#else
-# define RW_COUNT(rwlp) ((rwlp)->count & RWSEM_ACTIVE_MASK)
-# define RW_READ_HELD(rwlp) ((RW_COUNT(rwlp) > 0) ? RW_COUNT(rwlp) : 0)
-# define RW_WRITE_HELD(rwlp) ((RW_COUNT(rwlp) < 0))
-# define rw_exit_locked(rwlp) up_read(rwlp)
-# define rw_tryenter_locked(rwlp) down_write_trylock(rwlp)
+ return (rwp->rw_owner);
#endif
+}
-#define rw_tryenter(rwlp, rw) \
-({ \
- int _rc_ = 0; \
- switch (rw) { \
- case RW_READER: _rc_ = down_read_trylock(rwlp); break; \
- case RW_WRITER: _rc_ = down_write_trylock(rwlp); break; \
- default: SBUG(); \
- } \
- _rc_; \
+#ifdef CONFIG_LOCKDEP
+static inline void
+spl_rw_set_type(krwlock_t *rwp, krw_type_t type)
+{
+ rwp->rw_type = type;
+}
+static inline void
+spl_rw_lockdep_off_maybe(krwlock_t *rwp) \
+{ \
+ if (rwp && rwp->rw_type == RW_NOLOCKDEP) \
+ lockdep_off(); \
+}
+static inline void
+spl_rw_lockdep_on_maybe(krwlock_t *rwp) \
+{ \
+ if (rwp && rwp->rw_type == RW_NOLOCKDEP) \
+ lockdep_on(); \
+}
+#else /* CONFIG_LOCKDEP */
+#define spl_rw_set_type(rwp, type)
+#define spl_rw_lockdep_off_maybe(rwp)
+#define spl_rw_lockdep_on_maybe(rwp)
+#endif /* CONFIG_LOCKDEP */
+
+static inline int
+RW_READ_HELD(krwlock_t *rwp)
+{
+ /*
+ * Linux 4.8 will set owner to 1 when read held instead of leave it
+ * NULL. So we check whether owner <= 1.
+ */
+ return (spl_rwsem_is_locked(SEM(rwp)) &&
+ (unsigned long)rw_owner(rwp) <= 1);
+}
+
+static inline int
+RW_WRITE_HELD(krwlock_t *rwp)
+{
+ return (rw_owner(rwp) == current);
+}
+
+static inline int
+RW_LOCK_HELD(krwlock_t *rwp)
+{
+ return (spl_rwsem_is_locked(SEM(rwp)));
+}
+
+/*
+ * The following functions must be a #define and not static inline.
+ * This ensures that the native linux semaphore functions (down/up)
+ * will be correctly located in the users code which is important
+ * for the built in kernel lock analysis tools
+ */
+/* BEGIN CSTYLED */
+#define rw_init(rwp, name, type, arg) \
+({ \
+ static struct lock_class_key __key; \
+ ASSERT(type == RW_DEFAULT || type == RW_NOLOCKDEP); \
+ \
+ __init_rwsem(SEM(rwp), #rwp, &__key); \
+ spl_rw_clear_owner(rwp); \
+ spl_rw_set_type(rwp, type); \
+})
+
+/*
+ * The Linux rwsem implementation does not require a matching destroy.
+ */
+#define rw_destroy(rwp) ((void) 0)
+
+#define rw_tryenter(rwp, rw) \
+({ \
+ int _rc_ = 0; \
+ \
+ spl_rw_lockdep_off_maybe(rwp); \
+ switch (rw) { \
+ case RW_READER: \
+ _rc_ = down_read_trylock(SEM(rwp)); \
+ break; \
+ case RW_WRITER: \
+ if ((_rc_ = down_write_trylock(SEM(rwp)))) \
+ spl_rw_set_owner(rwp); \
+ break; \
+ default: \
+ VERIFY(0); \
+ } \
+ spl_rw_lockdep_on_maybe(rwp); \
+ _rc_; \
})
-#define rw_enter(rwlp, rw) \
-({ \
- switch (rw) { \
- case RW_READER: down_read(rwlp); break; \
- case RW_WRITER: down_write(rwlp); break; \
- default: SBUG(); \
- } \
+#define rw_enter(rwp, rw) \
+({ \
+ spl_rw_lockdep_off_maybe(rwp); \
+ switch (rw) { \
+ case RW_READER: \
+ down_read(SEM(rwp)); \
+ break; \
+ case RW_WRITER: \
+ down_write(SEM(rwp)); \
+ spl_rw_set_owner(rwp); \
+ break; \
+ default: \
+ VERIFY(0); \
+ } \
+ spl_rw_lockdep_on_maybe(rwp); \
})
-#define rw_exit(rwlp) \
-({ \
- if (RW_READ_HELD(rwlp)) \
- up_read(rwlp); \
- else if (RW_WRITE_HELD(rwlp)) \
- up_write(rwlp); \
- else \
- SBUG(); \
+#define rw_exit(rwp) \
+({ \
+ spl_rw_lockdep_off_maybe(rwp); \
+ if (RW_WRITE_HELD(rwp)) { \
+ spl_rw_clear_owner(rwp); \
+ up_write(SEM(rwp)); \
+ } else { \
+ ASSERT(RW_READ_HELD(rwp)); \
+ up_read(SEM(rwp)); \
+ } \
+ spl_rw_lockdep_on_maybe(rwp); \
})
-#define rw_tryupgrade(rwlp) \
-({ \
- unsigned long flags; \
- int _rc_ = 0; \
- spin_lock_irqsave(&(rwlp)->wait_lock, flags); \
- if (list_empty(&(rwlp)->wait_list) && (RW_READ_HELD(rwlp) == 1)) { \
- rw_exit_locked(rwlp); \
- _rc_ = rw_tryenter_locked(rwlp); \
- ASSERT(_rc_); \
- } \
- spin_unlock_irqrestore(&(rwlp)->wait_lock, flags); \
- _rc_; \
+#define rw_downgrade(rwp) \
+({ \
+ spl_rw_lockdep_off_maybe(rwp); \
+ spl_rw_clear_owner(rwp); \
+ downgrade_write(SEM(rwp)); \
+ spl_rw_lockdep_on_maybe(rwp); \
})
+#define rw_tryupgrade(rwp) \
+({ \
+ int _rc_ = 0; \
+ \
+ if (RW_WRITE_HELD(rwp)) { \
+ _rc_ = 1; \
+ } else { \
+ spl_rw_lockdep_off_maybe(rwp); \
+ if ((_rc_ = rwsem_tryupgrade(SEM(rwp)))) \
+ spl_rw_set_owner(rwp); \
+ spl_rw_lockdep_on_maybe(rwp); \
+ } \
+ _rc_; \
+})
+/* END CSTYLED */
+
+int spl_rw_init(void);
+void spl_rw_fini(void);
+
#endif /* _SPL_RWLOCK_H */
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