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/export.h>
18#include <linux/stringify.h>
19#include <linux/smp.h>
20
21/* waiting for a spinlock... */
22#if defined(CONFIG_PPC_SPLPAR)
23#include <asm/hvcall.h>
24#include <asm/smp.h>
25
26void __spin_yield(arch_spinlock_t *lock)
27{
28	unsigned int lock_value, holder_cpu, yield_count;
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);
35	yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
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 */
41	plpar_hcall_norets(H_CONFER,
42		get_hard_smp_processor_id(holder_cpu), yield_count);
43}
44EXPORT_SYMBOL_GPL(__spin_yield);
45
46/*
47 * Waiting for a read lock or a write lock on a rwlock...
48 * This turns out to be the same for read and write locks, since
49 * we only know the holder if it is write-locked.
50 */
51void __rw_yield(arch_rwlock_t *rw)
52{
53	int lock_value;
54	unsigned int holder_cpu, yield_count;
55
56	lock_value = rw->lock;
57	if (lock_value >= 0)
58		return;		/* no write lock at present */
59	holder_cpu = lock_value & 0xffff;
60	BUG_ON(holder_cpu >= NR_CPUS);
61	yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
62	if ((yield_count & 1) == 0)
63		return;		/* virtual cpu is currently running */
64	rmb();
65	if (rw->lock != lock_value)
66		return;		/* something has changed */
67	plpar_hcall_norets(H_CONFER,
68		get_hard_smp_processor_id(holder_cpu), yield_count);
69}
70#endif

 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/export.h>
18#include <linux/stringify.h>
19#include <linux/smp.h>
20
21/* waiting for a spinlock... */
22#if defined(CONFIG_PPC_SPLPAR)
23#include <asm/hvcall.h>
24#include <asm/smp.h>
25
26void __spin_yield(arch_spinlock_t *lock)
27{
28	unsigned int lock_value, holder_cpu, yield_count;
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);
35	yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
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 */
41	plpar_hcall_norets(H_CONFER,
42		get_hard_smp_processor_id(holder_cpu), yield_count);
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 */
50void __rw_yield(arch_rwlock_t *rw)
51{
52	int lock_value;
53	unsigned int holder_cpu, yield_count;
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);
60	yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
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 */
66	plpar_hcall_norets(H_CONFER,
67		get_hard_smp_processor_id(holder_cpu), yield_count);
68}
69#endif
70
71void arch_spin_unlock_wait(arch_spinlock_t *lock)
72{
73	while (lock->slock) {
74		HMT_low();
75		if (SHARED_PROCESSOR)
76			__spin_yield(lock);
77	}
78	HMT_medium();
79}
80
81EXPORT_SYMBOL(arch_spin_unlock_wait);