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65 lines
1.7 KiB
65 lines
1.7 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Spin and read/write lock operations. |
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* |
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* Copyright (C) 2001-2004 Paul Mackerras <[email protected]>, IBM |
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* Copyright (C) 2001 Anton Blanchard <[email protected]>, IBM |
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* Copyright (C) 2002 Dave Engebretsen <[email protected]>, IBM |
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* Rework to support virtual processors |
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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/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 splpar_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 = yield_count_of(holder_cpu); |
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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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yield_to_preempted(holder_cpu, yield_count); |
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} |
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EXPORT_SYMBOL_GPL(splpar_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 splpar_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 = yield_count_of(holder_cpu); |
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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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yield_to_preempted(holder_cpu, yield_count); |
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} |
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#endif
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