diff options
Diffstat (limited to 'arch/ppc64/lib/locks.c')
| -rw-r--r-- | arch/ppc64/lib/locks.c | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/arch/ppc64/lib/locks.c b/arch/ppc64/lib/locks.c new file mode 100644 index 000000000000..ef70ef91abe2 --- /dev/null +++ b/arch/ppc64/lib/locks.c @@ -0,0 +1,95 @@ +/* + * 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/config.h> +#include <linux/kernel.h> +#include <linux/spinlock.h> +#include <linux/module.h> +#include <linux/stringify.h> +#include <asm/hvcall.h> +#include <asm/iSeries/HvCall.h> + +/* waiting for a spinlock... */ +#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES) + +void __spin_yield(spinlock_t *lock) +{ + unsigned int lock_value, holder_cpu, yield_count; + struct paca_struct *holder_paca; + + lock_value = lock->lock; + if (lock_value == 0) + return; + holder_cpu = lock_value & 0xffff; + BUG_ON(holder_cpu >= NR_CPUS); + holder_paca = &paca[holder_cpu]; + yield_count = holder_paca->lppaca.yield_count; + if ((yield_count & 1) == 0) + return; /* virtual cpu is currently running */ + rmb(); + if (lock->lock != lock_value) + return; /* something has changed */ +#ifdef CONFIG_PPC_ISERIES + HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc, + ((u64)holder_cpu << 32) | yield_count); +#else + plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu), + yield_count); +#endif +} + +/* + * 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(rwlock_t *rw) +{ + int lock_value; + unsigned int holder_cpu, yield_count; + struct paca_struct *holder_paca; + + 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); + holder_paca = &paca[holder_cpu]; + yield_count = holder_paca->lppaca.yield_count; + if ((yield_count & 1) == 0) + return; /* virtual cpu is currently running */ + rmb(); + if (rw->lock != lock_value) + return; /* something has changed */ +#ifdef CONFIG_PPC_ISERIES + HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc, + ((u64)holder_cpu << 32) | yield_count); +#else + plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu), + yield_count); +#endif +} +#endif + +void spin_unlock_wait(spinlock_t *lock) +{ + while (lock->lock) { + HMT_low(); + if (SHARED_PROCESSOR) + __spin_yield(lock); + } + HMT_medium(); +} + +EXPORT_SYMBOL(spin_unlock_wait); |