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1da177e4 LT |
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 | ||
15 | #include <linux/config.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/spinlock.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/stringify.h> | |
20 | #include <asm/hvcall.h> | |
21 | #include <asm/iSeries/HvCall.h> | |
22 | ||
23 | /* waiting for a spinlock... */ | |
24 | #if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES) | |
25 | ||
fb1c8f93 | 26 | void __spin_yield(raw_spinlock_t *lock) |
1da177e4 LT |
27 | { |
28 | unsigned int lock_value, holder_cpu, yield_count; | |
29 | struct paca_struct *holder_paca; | |
30 | ||
fb1c8f93 | 31 | lock_value = lock->slock; |
1da177e4 LT |
32 | if (lock_value == 0) |
33 | return; | |
34 | holder_cpu = lock_value & 0xffff; | |
35 | BUG_ON(holder_cpu >= NR_CPUS); | |
36 | holder_paca = &paca[holder_cpu]; | |
37 | yield_count = holder_paca->lppaca.yield_count; | |
38 | if ((yield_count & 1) == 0) | |
39 | return; /* virtual cpu is currently running */ | |
40 | rmb(); | |
fb1c8f93 | 41 | if (lock->slock != lock_value) |
1da177e4 LT |
42 | return; /* something has changed */ |
43 | #ifdef CONFIG_PPC_ISERIES | |
44 | HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc, | |
45 | ((u64)holder_cpu << 32) | yield_count); | |
46 | #else | |
47 | plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu), | |
48 | yield_count); | |
49 | #endif | |
50 | } | |
51 | ||
52 | /* | |
53 | * Waiting for a read lock or a write lock on a rwlock... | |
54 | * This turns out to be the same for read and write locks, since | |
55 | * we only know the holder if it is write-locked. | |
56 | */ | |
fb1c8f93 | 57 | void __rw_yield(raw_rwlock_t *rw) |
1da177e4 LT |
58 | { |
59 | int lock_value; | |
60 | unsigned int holder_cpu, yield_count; | |
61 | struct paca_struct *holder_paca; | |
62 | ||
63 | lock_value = rw->lock; | |
64 | if (lock_value >= 0) | |
65 | return; /* no write lock at present */ | |
66 | holder_cpu = lock_value & 0xffff; | |
67 | BUG_ON(holder_cpu >= NR_CPUS); | |
68 | holder_paca = &paca[holder_cpu]; | |
69 | yield_count = holder_paca->lppaca.yield_count; | |
70 | if ((yield_count & 1) == 0) | |
71 | return; /* virtual cpu is currently running */ | |
72 | rmb(); | |
73 | if (rw->lock != lock_value) | |
74 | return; /* something has changed */ | |
75 | #ifdef CONFIG_PPC_ISERIES | |
76 | HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc, | |
77 | ((u64)holder_cpu << 32) | yield_count); | |
78 | #else | |
79 | plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu), | |
80 | yield_count); | |
81 | #endif | |
82 | } | |
83 | #endif | |
84 | ||
fb1c8f93 | 85 | void __raw_spin_unlock_wait(raw_spinlock_t *lock) |
1da177e4 | 86 | { |
fb1c8f93 | 87 | while (lock->slock) { |
1da177e4 LT |
88 | HMT_low(); |
89 | if (SHARED_PROCESSOR) | |
90 | __spin_yield(lock); | |
91 | } | |
92 | HMT_medium(); | |
93 | } | |
94 | ||
fb1c8f93 | 95 | EXPORT_SYMBOL(__raw_spin_unlock_wait); |