Eric Lee / smarc-fsl-linux-kernel

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kernel/rwsem.c 2.42 KB
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c4e05116a   Ingo Molnar   [PATCH] lockdep: ... 
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  /* 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/module.h>
  #include <linux/rwsem.h>
  
  #include <asm/system.h>
  #include <asm/atomic.h>
  
  /*
   * lock for reading
   */
  void down_read(struct rw_semaphore *sem)
  {
  	might_sleep();
  	rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
  
  	__down_read(sem);
  }
  
  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 down_write(struct rw_semaphore *sem)
  {
  	might_sleep();
  	rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
  
  	__down_write(sem);
  }
  
  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, 0, _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);
4ea2176df   Ingo Molnar   [PATCH] lockdep: ... 
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  #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_);
  
  	__down_read(sem);
  }
  
  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_);
  
  	__down_write_nested(sem, subclass);
  }
  
  EXPORT_SYMBOL(down_write_nested);
  
  void up_read_non_owner(struct rw_semaphore *sem)
  {
  	__up_read(sem);
  }
  
  EXPORT_SYMBOL(up_read_non_owner);
  
  #endif