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Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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Linus Torvalds
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#ifndef _ALPHA_RWSEM_H
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#define _ALPHA_RWSEM_H
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/*
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* Written by Ivan Kokshaysky <ink@jurassic.park.msu.ru>, 2001.
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* Based on asm-alpha/semaphore.h and asm-i386/rwsem.h
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*/
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#ifndef _LINUX_RWSEM_H
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#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
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#endif
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#ifdef __KERNEL__
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#include <linux/compiler.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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struct rwsem_waiter;
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extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
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extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
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extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *);
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extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
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/*
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* the semaphore definition
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*/
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struct rw_semaphore {
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long count;
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#define RWSEM_UNLOCKED_VALUE 0x0000000000000000L
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#define RWSEM_ACTIVE_BIAS 0x0000000000000001L
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#define RWSEM_ACTIVE_MASK 0x00000000ffffffffL
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#define RWSEM_WAITING_BIAS (-0x0000000100000000L)
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#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
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#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
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spinlock_t wait_lock;
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struct list_head wait_list;
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#if RWSEM_DEBUG
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int debug;
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#endif
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};
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#if RWSEM_DEBUG
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#define __RWSEM_DEBUG_INIT , 0
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#else
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#define __RWSEM_DEBUG_INIT /* */
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#endif
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#define __RWSEM_INITIALIZER(name) \
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{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \
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LIST_HEAD_INIT((name).wait_list) __RWSEM_DEBUG_INIT }
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#define DECLARE_RWSEM(name) \
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struct rw_semaphore name = __RWSEM_INITIALIZER(name)
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static inline void init_rwsem(struct rw_semaphore *sem)
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{
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sem->count = RWSEM_UNLOCKED_VALUE;
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spin_lock_init(&sem->wait_lock);
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INIT_LIST_HEAD(&sem->wait_list);
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#if RWSEM_DEBUG
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sem->debug = 0;
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#endif
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}
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static inline void __down_read(struct rw_semaphore *sem)
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{
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long oldcount;
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#ifndef CONFIG_SMP
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oldcount = sem->count;
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sem->count += RWSEM_ACTIVE_READ_BIAS;
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#else
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long temp;
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__asm__ __volatile__(
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"1: ldq_l %0,%1\n"
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" addq %0,%3,%2\n"
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" stq_c %2,%1\n"
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" beq %2,2f\n"
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" mb\n"
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".subsection 2\n"
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"2: br 1b\n"
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".previous"
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:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
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:"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");
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#endif
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if (unlikely(oldcount < 0))
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rwsem_down_read_failed(sem);
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}
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/*
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* trylock for reading -- returns 1 if successful, 0 if contention
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*/
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static inline int __down_read_trylock(struct rw_semaphore *sem)
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{
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long old, new, res;
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res = sem->count;
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do {
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new = res + RWSEM_ACTIVE_READ_BIAS;
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if (new <= 0)
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break;
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old = res;
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res = cmpxchg(&sem->count, old, new);
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} while (res != old);
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return res >= 0 ? 1 : 0;
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}
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static inline void __down_write(struct rw_semaphore *sem)
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{
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long oldcount;
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#ifndef CONFIG_SMP
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oldcount = sem->count;
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sem->count += RWSEM_ACTIVE_WRITE_BIAS;
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#else
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long temp;
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__asm__ __volatile__(
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"1: ldq_l %0,%1\n"
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" addq %0,%3,%2\n"
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" stq_c %2,%1\n"
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" beq %2,2f\n"
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" mb\n"
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".subsection 2\n"
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"2: br 1b\n"
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".previous"
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:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
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:"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");
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#endif
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if (unlikely(oldcount))
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rwsem_down_write_failed(sem);
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}
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/*
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* trylock for writing -- returns 1 if successful, 0 if contention
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*/
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static inline int __down_write_trylock(struct rw_semaphore *sem)
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{
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long ret = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
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RWSEM_ACTIVE_WRITE_BIAS);
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if (ret == RWSEM_UNLOCKED_VALUE)
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return 1;
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return 0;
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}
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static inline void __up_read(struct rw_semaphore *sem)
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{
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long oldcount;
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#ifndef CONFIG_SMP
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oldcount = sem->count;
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sem->count -= RWSEM_ACTIVE_READ_BIAS;
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#else
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long temp;
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__asm__ __volatile__(
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" mb\n"
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"1: ldq_l %0,%1\n"
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" subq %0,%3,%2\n"
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" stq_c %2,%1\n"
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" beq %2,2f\n"
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".subsection 2\n"
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"2: br 1b\n"
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".previous"
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:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
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:"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");
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#endif
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if (unlikely(oldcount < 0))
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if ((int)oldcount - RWSEM_ACTIVE_READ_BIAS == 0)
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rwsem_wake(sem);
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}
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static inline void __up_write(struct rw_semaphore *sem)
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{
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long count;
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#ifndef CONFIG_SMP
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sem->count -= RWSEM_ACTIVE_WRITE_BIAS;
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count = sem->count;
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#else
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long temp;
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__asm__ __volatile__(
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" mb\n"
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"1: ldq_l %0,%1\n"
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" subq %0,%3,%2\n"
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" stq_c %2,%1\n"
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" beq %2,2f\n"
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" subq %0,%3,%0\n"
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".subsection 2\n"
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"2: br 1b\n"
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".previous"
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:"=&r" (count), "=m" (sem->count), "=&r" (temp)
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:"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");
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#endif
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if (unlikely(count))
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if ((int)count == 0)
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rwsem_wake(sem);
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}
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/*
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* downgrade write lock to read lock
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*/
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static inline void __downgrade_write(struct rw_semaphore *sem)
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{
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long oldcount;
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#ifndef CONFIG_SMP
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oldcount = sem->count;
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sem->count -= RWSEM_WAITING_BIAS;
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#else
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long temp;
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__asm__ __volatile__(
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"1: ldq_l %0,%1\n"
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" addq %0,%3,%2\n"
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" stq_c %2,%1\n"
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" beq %2,2f\n"
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" mb\n"
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".subsection 2\n"
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"2: br 1b\n"
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".previous"
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:"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
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:"Ir" (-RWSEM_WAITING_BIAS), "m" (sem->count) : "memory");
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#endif
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if (unlikely(oldcount < 0))
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rwsem_downgrade_wake(sem);
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}
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static inline void rwsem_atomic_add(long val, struct rw_semaphore *sem)
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{
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#ifndef CONFIG_SMP
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sem->count += val;
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#else
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long temp;
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__asm__ __volatile__(
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"1: ldq_l %0,%1\n"
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" addq %0,%2,%0\n"
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" stq_c %0,%1\n"
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" beq %0,2f\n"
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".subsection 2\n"
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"2: br 1b\n"
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".previous"
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:"=&r" (temp), "=m" (sem->count)
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:"Ir" (val), "m" (sem->count));
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#endif
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}
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static inline long rwsem_atomic_update(long val, struct rw_semaphore *sem)
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{
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#ifndef CONFIG_SMP
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sem->count += val;
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return sem->count;
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#else
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long ret, temp;
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__asm__ __volatile__(
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"1: ldq_l %0,%1\n"
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" addq %0,%3,%2\n"
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" addq %0,%3,%0\n"
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" stq_c %2,%1\n"
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" beq %2,2f\n"
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".subsection 2\n"
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"2: br 1b\n"
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".previous"
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:"=&r" (ret), "=m" (sem->count), "=&r" (temp)
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:"Ir" (val), "m" (sem->count));
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return ret;
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#endif
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}
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#endif /* __KERNEL__ */
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#endif /* _ALPHA_RWSEM_H */
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