diff options
Diffstat (limited to 'arch/powerpc/lib/locks.c')
| -rw-r--r-- | arch/powerpc/lib/locks.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c new file mode 100644 index 000000000..35a0ef932 --- /dev/null +++ b/arch/powerpc/lib/locks.c @@ -0,0 +1,69 @@ +/* + * Spin and read/write lock operations. + * + * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM + * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM + * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM + * Rework to support virtual processors + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#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 __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 = be32_to_cpu(lppaca_of(holder_cpu).yield_count); + if ((yield_count & 1) == 0) + return; /* virtual cpu is currently running */ + rmb(); + if (lock->slock != lock_value) + return; /* something has changed */ + plpar_hcall_norets(H_CONFER, + get_hard_smp_processor_id(holder_cpu), yield_count); +} +EXPORT_SYMBOL_GPL(__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 __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 = be32_to_cpu(lppaca_of(holder_cpu).yield_count); + if ((yield_count & 1) == 0) + return; /* virtual cpu is currently running */ + rmb(); + if (rw->lock != lock_value) + return; /* something has changed */ + plpar_hcall_norets(H_CONFER, + get_hard_smp_processor_id(holder_cpu), yield_count); +} +#endif |