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1 /*****************************************************************************\
2 * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
3 * Copyright (C) 2007 The Regents of the University of California.
4 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
5 * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
8 * This file is part of the SPL, Solaris Porting Layer.
9 * For details, see <http://zfsonlinux.org/>.
11 * The SPL is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the
13 * Free Software Foundation; either version 2 of the License, or (at your
14 * option) any later version.
16 * The SPL is distributed in the hope that it will be useful, but WITHOUT
17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
21 * You should have received a copy of the GNU General Public License along
22 * with the SPL. If not, see <http://www.gnu.org/licenses/>.
23 \*****************************************************************************/
28 #include <sys/types.h>
29 #include <linux/rwsem.h>
30 #include <linux/rwsem_compat.h>
45 * If CONFIG_RWSEM_SPIN_ON_OWNER is defined, rw_semaphore will have an owner
46 * field, so we don't need our own.
49 struct rw_semaphore rw_rwlock
;
50 #ifndef CONFIG_RWSEM_SPIN_ON_OWNER
55 #endif /* CONFIG_LOCKDEP */
58 #define SEM(rwp) (&(rwp)->rw_rwlock)
61 spl_rw_set_owner(krwlock_t
*rwp
)
64 * If CONFIG_RWSEM_SPIN_ON_OWNER is defined, down_write, up_write,
65 * downgrade_write and __init_rwsem will set/clear owner for us.
67 #ifndef CONFIG_RWSEM_SPIN_ON_OWNER
68 rwp
->rw_owner
= current
;
73 spl_rw_clear_owner(krwlock_t
*rwp
)
75 #ifndef CONFIG_RWSEM_SPIN_ON_OWNER
80 static inline kthread_t
*
81 rw_owner(krwlock_t
*rwp
)
83 #ifdef CONFIG_RWSEM_SPIN_ON_OWNER
84 return (SEM(rwp
)->owner
);
86 return (rwp
->rw_owner
);
92 spl_rw_set_type(krwlock_t
*rwp
, krw_type_t type
)
97 spl_rw_lockdep_off_maybe(krwlock_t
*rwp
) \
99 if (rwp
&& rwp
->rw_type
== RW_NOLOCKDEP
) \
103 spl_rw_lockdep_on_maybe(krwlock_t
*rwp
) \
105 if (rwp
&& rwp
->rw_type
== RW_NOLOCKDEP
) \
108 #else /* CONFIG_LOCKDEP */
109 #define spl_rw_set_type(rwp, type)
110 #define spl_rw_lockdep_off_maybe(rwp)
111 #define spl_rw_lockdep_on_maybe(rwp)
112 #endif /* CONFIG_LOCKDEP */
115 RW_READ_HELD(krwlock_t
*rwp
)
118 * Linux 4.8 will set owner to 1 when read held instead of leave it
119 * NULL. So we check whether owner <= 1.
121 return (spl_rwsem_is_locked(SEM(rwp
)) &&
122 (unsigned long)rw_owner(rwp
) <= 1);
126 RW_WRITE_HELD(krwlock_t
*rwp
)
128 return (rw_owner(rwp
) == current
);
132 RW_LOCK_HELD(krwlock_t
*rwp
)
134 return (spl_rwsem_is_locked(SEM(rwp
)));
138 * The following functions must be a #define and not static inline.
139 * This ensures that the native linux semaphore functions (down/up)
140 * will be correctly located in the users code which is important
141 * for the built in kernel lock analysis tools
144 #define rw_init(rwp, name, type, arg) \
146 static struct lock_class_key __key; \
147 ASSERT(type == RW_DEFAULT || type == RW_NOLOCKDEP); \
149 __init_rwsem(SEM(rwp), #rwp, &__key); \
150 spl_rw_clear_owner(rwp); \
151 spl_rw_set_type(rwp, type); \
155 * The Linux rwsem implementation does not require a matching destroy.
157 #define rw_destroy(rwp) ((void) 0)
159 #define rw_tryenter(rwp, rw) \
163 spl_rw_lockdep_off_maybe(rwp); \
166 _rc_ = down_read_trylock(SEM(rwp)); \
169 if ((_rc_ = down_write_trylock(SEM(rwp)))) \
170 spl_rw_set_owner(rwp); \
175 spl_rw_lockdep_on_maybe(rwp); \
179 #define rw_enter(rwp, rw) \
181 spl_rw_lockdep_off_maybe(rwp); \
184 down_read(SEM(rwp)); \
187 down_write(SEM(rwp)); \
188 spl_rw_set_owner(rwp); \
193 spl_rw_lockdep_on_maybe(rwp); \
196 #define rw_exit(rwp) \
198 spl_rw_lockdep_off_maybe(rwp); \
199 if (RW_WRITE_HELD(rwp)) { \
200 spl_rw_clear_owner(rwp); \
201 up_write(SEM(rwp)); \
203 ASSERT(RW_READ_HELD(rwp)); \
206 spl_rw_lockdep_on_maybe(rwp); \
209 #define rw_downgrade(rwp) \
211 spl_rw_lockdep_off_maybe(rwp); \
212 spl_rw_clear_owner(rwp); \
213 downgrade_write(SEM(rwp)); \
214 spl_rw_lockdep_on_maybe(rwp); \
217 #define rw_tryupgrade(rwp) \
221 if (RW_WRITE_HELD(rwp)) { \
224 spl_rw_lockdep_off_maybe(rwp); \
225 if ((_rc_ = rwsem_tryupgrade(SEM(rwp)))) \
226 spl_rw_set_owner(rwp); \
227 spl_rw_lockdep_on_maybe(rwp); \
233 int spl_rw_init(void);
234 void spl_rw_fini(void);
236 #endif /* _SPL_RWLOCK_H */