[PATCH] Make mkcompile_h use LANG=C and LC_ALL=C for $CC -v
[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(raw_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[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         else
47                 plpar_hcall_norets(H_CONFER,
48                         get_hard_smp_processor_id(holder_cpu), yield_count);
49 }
50
51 /*
52  * Waiting for a read lock or a write lock on a rwlock...
53  * This turns out to be the same for read and write locks, since
54  * we only know the holder if it is write-locked.
55  */
56 void __rw_yield(raw_rwlock_t *rw)
57 {
58         int lock_value;
59         unsigned int holder_cpu, yield_count;
60
61         lock_value = rw->lock;
62         if (lock_value >= 0)
63                 return;         /* no write lock at present */
64         holder_cpu = lock_value & 0xffff;
65         BUG_ON(holder_cpu >= NR_CPUS);
66         yield_count = lppaca[holder_cpu].yield_count;
67         if ((yield_count & 1) == 0)
68                 return;         /* virtual cpu is currently running */
69         rmb();
70         if (rw->lock != lock_value)
71                 return;         /* something has changed */
72         if (firmware_has_feature(FW_FEATURE_ISERIES))
73                 HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
74                         ((u64)holder_cpu << 32) | yield_count);
75         else
76                 plpar_hcall_norets(H_CONFER,
77                         get_hard_smp_processor_id(holder_cpu), yield_count);
78 }
79 #endif
80
81 void __raw_spin_unlock_wait(raw_spinlock_t *lock)
82 {
83         while (lock->slock) {
84                 HMT_low();
85                 if (SHARED_PROCESSOR)
86                         __spin_yield(lock);
87         }
88         HMT_medium();
89 }
90
91 EXPORT_SYMBOL(__raw_spin_unlock_wait);