2 * Spin and read/write lock operations.
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
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.
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>
21 /* waiting for a spinlock... */
22 #if defined(CONFIG_PPC_SPLPAR)
23 #include <asm/hvcall.h>
26 void __spin_yield(arch_spinlock_t
*lock
)
28 unsigned int lock_value
, holder_cpu
, yield_count
;
30 lock_value
= lock
->slock
;
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 */
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
);
44 EXPORT_SYMBOL_GPL(__spin_yield
);
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.
51 void __rw_yield(arch_rwlock_t
*rw
)
54 unsigned int holder_cpu
, yield_count
;
56 lock_value
= rw
->lock
;
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 */
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
);
72 void arch_spin_unlock_wait(arch_spinlock_t
*lock
)
86 EXPORT_SYMBOL(arch_spin_unlock_wait
);
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