Commit | Line | Data |
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40ef8cbc PM |
1 | /* |
2 | * Spin and read/write lock operations. | |
3 | * | |
4 | * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM | |
5 | * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM | |
6 | * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM | |
7 | * Rework to support virtual processors | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU General Public License | |
11 | * as published by the Free Software Foundation; either version | |
12 | * 2 of the License, or (at your option) any later version. | |
13 | */ | |
14 | ||
40ef8cbc PM |
15 | #include <linux/kernel.h> |
16 | #include <linux/spinlock.h> | |
4b16f8e2 | 17 | #include <linux/export.h> |
40ef8cbc | 18 | #include <linux/stringify.h> |
734d6524 | 19 | #include <linux/smp.h> |
40ef8cbc PM |
20 | |
21 | /* waiting for a spinlock... */ | |
f5339277 | 22 | #if defined(CONFIG_PPC_SPLPAR) |
40ef8cbc | 23 | #include <asm/hvcall.h> |
2249ca9d | 24 | #include <asm/smp.h> |
40ef8cbc | 25 | |
445c8951 | 26 | void __spin_yield(arch_spinlock_t *lock) |
40ef8cbc PM |
27 | { |
28 | unsigned int lock_value, holder_cpu, yield_count; | |
40ef8cbc PM |
29 | |
30 | lock_value = lock->slock; | |
31 | if (lock_value == 0) | |
32 | return; | |
33 | holder_cpu = lock_value & 0xffff; | |
34 | BUG_ON(holder_cpu >= NR_CPUS); | |
8154c5d2 | 35 | yield_count = lppaca_of(holder_cpu).yield_count; |
40ef8cbc PM |
36 | if ((yield_count & 1) == 0) |
37 | return; /* virtual cpu is currently running */ | |
38 | rmb(); | |
39 | if (lock->slock != lock_value) | |
40 | return; /* something has changed */ | |
f5339277 SR |
41 | plpar_hcall_norets(H_CONFER, |
42 | get_hard_smp_processor_id(holder_cpu), yield_count); | |
40ef8cbc PM |
43 | } |
44 | ||
45 | /* | |
46 | * Waiting for a read lock or a write lock on a rwlock... | |
47 | * This turns out to be the same for read and write locks, since | |
48 | * we only know the holder if it is write-locked. | |
49 | */ | |
fb3a6bbc | 50 | void __rw_yield(arch_rwlock_t *rw) |
40ef8cbc PM |
51 | { |
52 | int lock_value; | |
53 | unsigned int holder_cpu, yield_count; | |
40ef8cbc PM |
54 | |
55 | lock_value = rw->lock; | |
56 | if (lock_value >= 0) | |
57 | return; /* no write lock at present */ | |
58 | holder_cpu = lock_value & 0xffff; | |
59 | BUG_ON(holder_cpu >= NR_CPUS); | |
8154c5d2 | 60 | yield_count = lppaca_of(holder_cpu).yield_count; |
40ef8cbc PM |
61 | if ((yield_count & 1) == 0) |
62 | return; /* virtual cpu is currently running */ | |
63 | rmb(); | |
64 | if (rw->lock != lock_value) | |
65 | return; /* something has changed */ | |
f5339277 SR |
66 | plpar_hcall_norets(H_CONFER, |
67 | get_hard_smp_processor_id(holder_cpu), yield_count); | |
40ef8cbc PM |
68 | } |
69 | #endif | |
70 | ||
0199c4e6 | 71 | void arch_spin_unlock_wait(arch_spinlock_t *lock) |
40ef8cbc PM |
72 | { |
73 | while (lock->slock) { | |
74 | HMT_low(); | |
75 | if (SHARED_PROCESSOR) | |
76 | __spin_yield(lock); | |
77 | } | |
78 | HMT_medium(); | |
79 | } | |
80 | ||
0199c4e6 | 81 | EXPORT_SYMBOL(arch_spin_unlock_wait); |