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86 lines
2.3 KiB
86 lines
2.3 KiB
/* |
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* Spin and read/write lock operations. |
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* |
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* Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM |
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* Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM |
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* Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM |
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* Rework to support virtual processors |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public License |
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* as published by the Free Software Foundation; either version |
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* 2 of the License, or (at your option) any later version. |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/spinlock.h> |
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#include <linux/export.h> |
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#include <linux/stringify.h> |
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#include <linux/smp.h> |
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/* waiting for a spinlock... */ |
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#if defined(CONFIG_PPC_SPLPAR) |
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#include <asm/hvcall.h> |
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#include <asm/smp.h> |
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void __spin_yield(arch_spinlock_t *lock) |
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{ |
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unsigned int lock_value, holder_cpu, yield_count; |
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lock_value = lock->slock; |
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if (lock_value == 0) |
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return; |
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holder_cpu = lock_value & 0xffff; |
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BUG_ON(holder_cpu >= NR_CPUS); |
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yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count); |
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if ((yield_count & 1) == 0) |
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return; /* virtual cpu is currently running */ |
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rmb(); |
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if (lock->slock != lock_value) |
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return; /* something has changed */ |
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plpar_hcall_norets(H_CONFER, |
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get_hard_smp_processor_id(holder_cpu), yield_count); |
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} |
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EXPORT_SYMBOL_GPL(__spin_yield); |
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/* |
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* Waiting for a read lock or a write lock on a rwlock... |
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* This turns out to be the same for read and write locks, since |
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* we only know the holder if it is write-locked. |
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*/ |
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void __rw_yield(arch_rwlock_t *rw) |
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{ |
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int lock_value; |
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unsigned int holder_cpu, yield_count; |
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lock_value = rw->lock; |
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if (lock_value >= 0) |
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return; /* no write lock at present */ |
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holder_cpu = lock_value & 0xffff; |
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BUG_ON(holder_cpu >= NR_CPUS); |
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yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count); |
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if ((yield_count & 1) == 0) |
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return; /* virtual cpu is currently running */ |
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rmb(); |
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if (rw->lock != lock_value) |
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return; /* something has changed */ |
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plpar_hcall_norets(H_CONFER, |
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get_hard_smp_processor_id(holder_cpu), yield_count); |
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} |
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#endif |
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void arch_spin_unlock_wait(arch_spinlock_t *lock) |
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{ |
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smp_mb(); |
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while (lock->slock) { |
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HMT_low(); |
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if (SHARED_PROCESSOR) |
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__spin_yield(lock); |
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} |
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HMT_medium(); |
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smp_mb(); |
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} |
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EXPORT_SYMBOL(arch_spin_unlock_wait);
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