projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 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); |