Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/* kernel/rwsem.c: R/W semaphores, public implementation

 *

 * Written by David Howells (dhowells@redhat.com).

 * Derived from asm-i386/semaphore.h

 */

#include <linux/types.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/module.h>

#include <linux/rwsem.h>

#include <asm/system.h>

#include <asm/atomic.h>

/*

 * lock for reading

 */

void __sched down_read(struct rw_semaphore *sem)

{

        might_sleep();

        rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);

        LOCK_CONTENDED(sem, __down_read_trylock, __down_read);

}

EXPORT_SYMBOL(down_read);

/*

 * trylock for reading -- returns 1 if successful, 0 if contention

 */

int down_read_trylock(struct rw_semaphore *sem)

{

        int ret = __down_read_trylock(sem);

        if (ret == 1)

                rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);

        return ret;

}

EXPORT_SYMBOL(down_read_trylock);

/*

 * lock for writing

 */

void __sched down_write(struct rw_semaphore *sem)

{

        might_sleep();

        rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);

        LOCK_CONTENDED(sem, __down_write_trylock, __down_write);

}

EXPORT_SYMBOL(down_write);

/*

 * trylock for writing -- returns 1 if successful, 0 if contention

 */

int down_write_trylock(struct rw_semaphore *sem)

{

        int ret = __down_write_trylock(sem);

        if (ret == 1)

                rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_);

        return ret;

}

EXPORT_SYMBOL(down_write_trylock);

/*

 * release a read lock

 */

void up_read(struct rw_semaphore *sem)

{

        rwsem_release(&sem->dep_map, 1, _RET_IP_);

        __up_read(sem);

}

EXPORT_SYMBOL(up_read);

/*

 * release a write lock

 */

void up_write(struct rw_semaphore *sem)

{

        rwsem_release(&sem->dep_map, 1, _RET_IP_);

        __up_write(sem);

}

EXPORT_SYMBOL(up_write);

/*

 * downgrade write lock to read lock

 */

void downgrade_write(struct rw_semaphore *sem)

{

        /*

         * lockdep: a downgraded write will live on as a write

         * dependency.

         */

        __downgrade_write(sem);

}

EXPORT_SYMBOL(downgrade_write);

#ifdef CONFIG_DEBUG_LOCK_ALLOC

void down_read_nested(struct rw_semaphore *sem, int subclass)

{

        might_sleep();

        rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_);

        LOCK_CONTENDED(sem, __down_read_trylock, __down_read);

}

EXPORT_SYMBOL(down_read_nested);

void down_read_non_owner(struct rw_semaphore *sem)

{

        might_sleep();

        __down_read(sem);

}

EXPORT_SYMBOL(down_read_non_owner);

void down_write_nested(struct rw_semaphore *sem, int subclass)

{

        might_sleep();

        rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_);

        LOCK_CONTENDED(sem, __down_write_trylock, __down_write);

}

EXPORT_SYMBOL(down_write_nested);

void up_read_non_owner(struct rw_semaphore *sem)

{

        __up_read(sem);

}

EXPORT_SYMBOL(up_read_non_owner);

#endif