projects / mirror_spl.git / blame
| Commit | Line | Data |
|---|---|---|
| 716154c5 BB |
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>. | |
| 715f6251 | 6 | * UCRL-CODE-235197 |
| 7 | * | |
| 716154c5 | 8 | * This file is part of the SPL, Solaris Porting Layer. |
| 3d6af2dd | 9 | * For details, see <http://zfsonlinux.org/>. |
| 715f6251 | 10 | * |
| 716154c5 BB |
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. | |
| 15 | * | |
| 16 | * The SPL is distributed in the hope that it will be useful, but WITHOUT | |
| 715f6251 | 17 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 18 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 19 | * for more details. | |
| 20 | * | |
| 21 | * You should have received a copy of the GNU General Public License along | |
| 716154c5 BB |
22 | * with the SPL. If not, see <http://www.gnu.org/licenses/>. |
| 23 | ***************************************************************************** | |
| 24 | * Solaris Porting Layer (SPL) Reader/Writer Lock Implementation. | |
| 25 | \*****************************************************************************/ | |
| 715f6251 | 26 | |
| f4b37741 | 27 | #include <sys/rwlock.h> |
| f1ca4da6 | 28 | |
| 937879f1 | 29 | #ifdef DEBUG_SUBSYSTEM |
| 30 | #undef DEBUG_SUBSYSTEM | |
| 31 | #endif | |
| 32 | ||
| 33 | #define DEBUG_SUBSYSTEM S_RWLOCK | |
| 34 | ||
| f58040c0 CC |
35 | #ifdef CONFIG_RWSEM_GENERIC_SPINLOCK |
| 36 | static int | |
| 37 | __rwsem_tryupgrade(struct rw_semaphore *rwsem) | |
| 38 | { | |
| 39 | int ret = 0; | |
| 40 | unsigned long flags; | |
| 41 | spl_rwsem_lock_irqsave(&rwsem->wait_lock, flags); | |
| 42 | if (RWSEM_COUNT(rwsem) == SPL_RWSEM_SINGLE_READER_VALUE && | |
| 43 | list_empty(&rwsem->wait_list)) { | |
| 44 | ret = 1; | |
| 45 | RWSEM_COUNT(rwsem) = SPL_RWSEM_SINGLE_WRITER_VALUE; | |
| 46 | } | |
| 47 | spl_rwsem_unlock_irqrestore(&rwsem->wait_lock, flags); | |
| 48 | return (ret); | |
| 49 | } | |
| 50 | #else | |
| 51 | static int | |
| 52 | __rwsem_tryupgrade(struct rw_semaphore *rwsem) | |
| 53 | { | |
| 54 | typeof (rwsem->count) val; | |
| 55 | val = cmpxchg(&rwsem->count, SPL_RWSEM_SINGLE_READER_VALUE, | |
| 56 | SPL_RWSEM_SINGLE_WRITER_VALUE); | |
| 57 | return (val == SPL_RWSEM_SINGLE_READER_VALUE); | |
| 58 | } | |
| 59 | #endif | |
| 60 | ||
| 61 | int | |
| 62 | rwsem_tryupgrade(struct rw_semaphore *rwsem) | |
| 63 | { | |
| 64 | if (__rwsem_tryupgrade(rwsem)) { | |
| 65 | rwsem_release(&rwsem->dep_map, 1, _RET_IP_); | |
| 66 | rwsem_acquire(&rwsem->dep_map, 0, 1, _RET_IP_); | |
| 67 | #ifdef CONFIG_RWSEM_SPIN_ON_OWNER | |
| 68 | rwsem->owner = current; | |
| 69 | #endif | |
| 70 | return (1); | |
| 71 | } | |
| 72 | return (0); | |
| 73 | } | |
| 74 | EXPORT_SYMBOL(rwsem_tryupgrade); | |
| 75 | ||
| d28db80f BB |
76 | int spl_rw_init(void) { return 0; } |
| 77 | void spl_rw_fini(void) { } |