powerpc: Enable lockup and hung task detectors in pseries and ppc64 defeconfigs
[linux-2.6.git] / arch / powerpc / lib / locks.c
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/kernel.h>
16 #include <linux/spinlock.h>
17 #include <linux/module.h>
18 #include <linux/stringify.h>
19 #include <linux/smp.h>
20
21 /* waiting for a spinlock... */
22 #if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
23 #include <asm/hvcall.h>
24 #include <asm/iseries/hv_call.h>
25 #include <asm/smp.h>
26 #include <asm/firmware.h>
27
28 void __spin_yield(arch_spinlock_t *lock)
29 {
30         unsigned int lock_value, holder_cpu, yield_count;
31
32         lock_value = lock->slock;
33         if (lock_value == 0)
34                 return;
35         holder_cpu = lock_value & 0xffff;
36         BUG_ON(holder_cpu >= NR_CPUS);
37         yield_count = lppaca_of(holder_cpu).yield_count;
38         if ((yield_count & 1) == 0)
39                 return;         /* virtual cpu is currently running */
40         rmb();
41         if (lock->slock != lock_value)
42                 return;         /* something has changed */
43         if (firmware_has_feature(FW_FEATURE_ISERIES))
44                 HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
45                         ((u64)holder_cpu << 32) | yield_count);
46 #ifdef CONFIG_PPC_SPLPAR
47         else
48                 plpar_hcall_norets(H_CONFER,
49                         get_hard_smp_processor_id(holder_cpu), yield_count);
50 #endif
51 }
52
53 /*
54  * Waiting for a read lock or a write lock on a rwlock...
55  * This turns out to be the same for read and write locks, since
56  * we only know the holder if it is write-locked.
57  */
58 void __rw_yield(arch_rwlock_t *rw)
59 {
60         int lock_value;
61         unsigned int holder_cpu, yield_count;
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         yield_count = lppaca_of(holder_cpu).yield_count;
69         if ((yield_count & 1) == 0)
70                 return;         /* virtual cpu is currently running */
71         rmb();
72         if (rw->lock != lock_value)
73                 return;         /* something has changed */
74         if (firmware_has_feature(FW_FEATURE_ISERIES))
75                 HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
76                         ((u64)holder_cpu << 32) | yield_count);
77 #ifdef CONFIG_PPC_SPLPAR
78         else
79                 plpar_hcall_norets(H_CONFER,
80                         get_hard_smp_processor_id(holder_cpu), yield_count);
81 #endif
82 }
83 #endif
84
85 void arch_spin_unlock_wait(arch_spinlock_t *lock)
86 {
87         while (lock->slock) {
88                 HMT_low();
89                 if (SHARED_PROCESSOR)
90                         __spin_yield(lock);
91         }
92         HMT_medium();
93 }
94
95 EXPORT_SYMBOL(arch_spin_unlock_wait);