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- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * Spin and read/write lock operations.
- *
- * Copyright (C) 2001-2004 Paul Mackerras <[email protected]>, IBM
- * Copyright (C) 2001 Anton Blanchard <[email protected]>, IBM
- * Copyright (C) 2002 Dave Engebretsen <[email protected]>, IBM
- * Rework to support virtual processors
- */
- #include <linux/kernel.h>
- #include <linux/spinlock.h>
- #include <linux/export.h>
- #include <linux/smp.h>
- /* waiting for a spinlock... */
- #if defined(CONFIG_PPC_SPLPAR)
- #include <asm/hvcall.h>
- #include <asm/smp.h>
- void splpar_spin_yield(arch_spinlock_t *lock)
- {
- unsigned int lock_value, holder_cpu, yield_count;
- lock_value = lock->slock;
- if (lock_value == 0)
- return;
- holder_cpu = lock_value & 0xffff;
- BUG_ON(holder_cpu >= NR_CPUS);
- yield_count = yield_count_of(holder_cpu);
- if ((yield_count & 1) == 0)
- return; /* virtual cpu is currently running */
- rmb();
- if (lock->slock != lock_value)
- return; /* something has changed */
- yield_to_preempted(holder_cpu, yield_count);
- }
- EXPORT_SYMBOL_GPL(splpar_spin_yield);
- /*
- * Waiting for a read lock or a write lock on a rwlock...
- * This turns out to be the same for read and write locks, since
- * we only know the holder if it is write-locked.
- */
- void splpar_rw_yield(arch_rwlock_t *rw)
- {
- int lock_value;
- unsigned int holder_cpu, yield_count;
- lock_value = rw->lock;
- if (lock_value >= 0)
- return; /* no write lock at present */
- holder_cpu = lock_value & 0xffff;
- BUG_ON(holder_cpu >= NR_CPUS);
- yield_count = yield_count_of(holder_cpu);
- if ((yield_count & 1) == 0)
- return; /* virtual cpu is currently running */
- rmb();
- if (rw->lock != lock_value)
- return; /* something has changed */
- yield_to_preempted(holder_cpu, yield_count);
- }
- #endif
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