| /* |
| * 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_RWLOCK_H |
| #define _SPL_RWLOCK_H |
| |
| #include <sys/types.h> |
| #include <linux/rwsem.h> |
| #include <linux/sched.h> |
| |
| typedef enum { |
| RW_DRIVER = 2, |
| RW_DEFAULT = 4, |
| RW_NOLOCKDEP = 5 |
| } krw_type_t; |
| |
| typedef enum { |
| RW_NONE = 0, |
| RW_WRITER = 1, |
| RW_READER = 2 |
| } krw_t; |
| |
| typedef struct { |
| struct rw_semaphore rw_rwlock; |
| kthread_t *rw_owner; |
| #ifdef CONFIG_LOCKDEP |
| krw_type_t rw_type; |
| #endif /* CONFIG_LOCKDEP */ |
| } krwlock_t; |
| |
| #define SEM(rwp) (&(rwp)->rw_rwlock) |
| |
| static inline void |
| spl_rw_set_owner(krwlock_t *rwp) |
| { |
| rwp->rw_owner = current; |
| } |
| |
| static inline void |
| spl_rw_clear_owner(krwlock_t *rwp) |
| { |
| rwp->rw_owner = NULL; |
| } |
| |
| static inline kthread_t * |
| rw_owner(krwlock_t *rwp) |
| { |
| return (rwp->rw_owner); |
| } |
| |
| #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_LOCK_HELD(krwlock_t *rwp) |
| { |
| return (rwsem_is_locked(SEM(rwp))); |
| } |
| |
| static inline int |
| RW_WRITE_HELD(krwlock_t *rwp) |
| { |
| return (rw_owner(rwp) == current); |
| } |
| |
| static inline int |
| RW_READ_HELD(krwlock_t *rwp) |
| { |
| return (RW_LOCK_HELD(rwp) && rw_owner(rwp) == NULL); |
| } |
| |
| /* |
| * 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) |
| |
| /* |
| * Upgrading a rwsem from a reader to a writer is not supported by the |
| * Linux kernel. The lock must be dropped and reacquired as a writer. |
| */ |
| #define rw_tryupgrade(rwp) RW_WRITE_HELD(rwp) |
| |
| #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(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(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_downgrade(rwp) \ |
| ({ \ |
| spl_rw_lockdep_off_maybe(rwp); \ |
| spl_rw_clear_owner(rwp); \ |
| downgrade_write(SEM(rwp)); \ |
| spl_rw_lockdep_on_maybe(rwp); \ |
| }) |
| /* END CSTYLED */ |
| |
| #endif /* _SPL_RWLOCK_H */ |