| /* |
| * 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/module.h> |
| #include <linux/stringify.h> |
| #include <linux/smp.h> |
| |
| /* waiting for a spinlock... */ |
| #if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES) |
| #include <asm/hvcall.h> |
| #include <asm/iseries/hv_call.h> |
| #include <asm/smp.h> |
| #include <asm/firmware.h> |
| |
| void __spin_yield(raw_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 = lppaca[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 */ |
| if (firmware_has_feature(FW_FEATURE_ISERIES)) |
| HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc, |
| ((u64)holder_cpu << 32) | yield_count); |
| #ifdef CONFIG_PPC_SPLPAR |
| 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(raw_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 = lppaca[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 */ |
| if (firmware_has_feature(FW_FEATURE_ISERIES)) |
| HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc, |
| ((u64)holder_cpu << 32) | yield_count); |
| #ifdef CONFIG_PPC_SPLPAR |
| else |
| plpar_hcall_norets(H_CONFER, |
| get_hard_smp_processor_id(holder_cpu), yield_count); |
| #endif |
| } |
| #endif |
| |
| void __raw_spin_unlock_wait(raw_spinlock_t *lock) |
| { |
| while (lock->slock) { |
| HMT_low(); |
| if (SHARED_PROCESSOR) |
| __spin_yield(lock); |
| } |
| HMT_medium(); |
| } |
| |
| EXPORT_SYMBOL(__raw_spin_unlock_wait); |