]>
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 | ||
0f836a62 AX |
35 | #if defined(CONFIG_RWSEM_GENERIC_SPINLOCK) |
36 | static int | |
37 | __rwsem_tryupgrade(struct rw_semaphore *rwsem) | |
e8b31e84 | 38 | { |
0f836a62 AX |
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); | |
e8b31e84 | 49 | } |
0f836a62 AX |
50 | #elif defined(HAVE_RWSEM_ATOMIC_LONG_COUNT) |
51 | static int | |
52 | __rwsem_tryupgrade(struct rw_semaphore *rwsem) | |
e8b31e84 | 53 | { |
0f836a62 AX |
54 | long val; |
55 | val = atomic_long_cmpxchg(&rwsem->count, SPL_RWSEM_SINGLE_READER_VALUE, | |
56 | SPL_RWSEM_SINGLE_WRITER_VALUE); | |
57 | return (val == SPL_RWSEM_SINGLE_READER_VALUE); | |
e8b31e84 | 58 | } |
0f836a62 AX |
59 | #else |
60 | static int | |
61 | __rwsem_tryupgrade(struct rw_semaphore *rwsem) | |
e8b31e84 | 62 | { |
0f836a62 AX |
63 | typeof (rwsem->count) val; |
64 | val = cmpxchg(&rwsem->count, SPL_RWSEM_SINGLE_READER_VALUE, | |
65 | SPL_RWSEM_SINGLE_WRITER_VALUE); | |
66 | return (val == SPL_RWSEM_SINGLE_READER_VALUE); | |
f1ca4da6 | 67 | } |
0f836a62 | 68 | #endif |
79f92663 | 69 | |
0f836a62 AX |
70 | int |
71 | rwsem_tryupgrade(struct rw_semaphore *rwsem) | |
72 | { | |
73 | if (__rwsem_tryupgrade(rwsem)) { | |
74 | rwsem_release(&rwsem->dep_map, 1, _RET_IP_); | |
75 | rwsem_acquire(&rwsem->dep_map, 0, 1, _RET_IP_); | |
76 | #ifdef CONFIG_RWSEM_SPIN_ON_OWNER | |
77 | rwsem->owner = current; | |
ed61a7d0 | 78 | #endif |
0f836a62 AX |
79 | return (1); |
80 | } | |
81 | return (0); | |
82 | } | |
83 | EXPORT_SYMBOL(rwsem_tryupgrade); | |
d28db80f BB |
84 | |
85 | int spl_rw_init(void) { return 0; } | |
86 | void spl_rw_fini(void) { } |