| 1 | |
| 2 | |
| 3 | * Spin and read/write lock operations.
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| 4 | *
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| 5 | * Copyright (C) 2001-2004 Paul Mackerras <[email protected]>, IBM
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| 6 | * Copyright (C) 2001 Anton Blanchard <[email protected]>, IBM
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| 7 | * Copyright (C) 2002 Dave Engebretsen <[email protected]>, IBM
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| 8 | * Rework to support virtual processors
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| 9 |
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| 10 |
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| 11 | #include <linux/kernel.h>
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| 12 | #include <linux/spinlock.h>
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| 13 | #include <linux/export.h>
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| 14 | #include <linux/smp.h>
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| 15 |
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| 16 |
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| 17 | #if defined(CONFIG_PPC_SPLPAR)
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| 18 | #include <asm/hvcall.h>
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| 19 | #include <asm/smp.h>
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| 20 |
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| 21 | void splpar_spin_yield(arch_spinlock_t *lock)
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| 22 | {
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| 23 | unsigned int lock_value, holder_cpu, yield_count;
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| 24 |
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| 25 | lock_value = lock->slock;
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| 26 | if (lock_value == 0)
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| 27 | return;
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| 28 | holder_cpu = lock_value & 0xffff;
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| 29 | BUG_ON(holder_cpu >= NR_CPUS);
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| 30 |
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| 31 | yield_count = yield_count_of(holder_cpu);
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| 32 | if ((yield_count & 1) == 0)
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| 33 | return;
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| 34 | rmb();
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| 35 | if (lock->slock != lock_value)
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| 36 | return;
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| 37 | yield_to_preempted(holder_cpu, yield_count);
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| 38 | }
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| 39 | EXPORT_SYMBOL_GPL(splpar_spin_yield);
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| 40 |
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| 41 | |
| 42 | * Waiting for a read lock or a write lock on a rwlock...
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| 43 | * This turns out to be the same for read and write locks, since
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| 44 | * we only know the holder if it is write-locked.
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| 45 |
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| 46 | void splpar_rw_yield(arch_rwlock_t *rw)
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| 47 | {
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| 48 | int lock_value;
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| 49 | unsigned int holder_cpu, yield_count;
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| 50 |
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| 51 | lock_value = rw->lock;
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| 52 | if (lock_value >= 0)
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| 53 | return;
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| 54 | holder_cpu = lock_value & 0xffff;
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| 55 | BUG_ON(holder_cpu >= NR_CPUS);
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| 56 |
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| 57 | yield_count = yield_count_of(holder_cpu);
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| 58 | if ((yield_count & 1) == 0)
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| 59 | return;
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| 60 | rmb();
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| 61 | if (rw->lock != lock_value)
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| 62 | return;
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| 63 | yield_to_preempted(holder_cpu, yield_count);
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| 64 | }
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| 65 | #endif
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