/*
   * Read-Copy Update definitions shared among RCU implementations.
   *
   * 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.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   *
   * Copyright IBM Corporation, 2011
   *
   * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
   */
  
  #ifndef __LINUX_RCU_H
  #define __LINUX_RCU_H

  #ifdef CONFIG_RCU_TRACE
  #define RCU_TRACE(stmt) stmt
  #else /* #ifdef CONFIG_RCU_TRACE */
  #define RCU_TRACE(stmt)
  #endif /* #else #ifdef CONFIG_RCU_TRACE */

  /*

   * Process-level increment to ->dynticks_nesting field.  This allows for
   * architectures that use half-interrupts and half-exceptions from
   * process context.

   *
   * DYNTICK_TASK_NEST_MASK defines a field of width DYNTICK_TASK_NEST_WIDTH
   * that counts the number of process-based reasons why RCU cannot
   * consider the corresponding CPU to be idle, and DYNTICK_TASK_NEST_VALUE
   * is the value used to increment or decrement this field.
   *
   * The rest of the bits could in principle be used to count interrupts,
   * but this would mean that a negative-one value in the interrupt
   * field could incorrectly zero out the DYNTICK_TASK_NEST_MASK field.
   * We therefore provide a two-bit guard field defined by DYNTICK_TASK_MASK
   * that is set to DYNTICK_TASK_FLAG upon initial exit from idle.
   * The DYNTICK_TASK_EXIT_IDLE value is thus the combined value used upon
   * initial exit from idle.

   */

  #define DYNTICK_TASK_NEST_WIDTH 7
  #define DYNTICK_TASK_NEST_VALUE ((LLONG_MAX >> DYNTICK_TASK_NEST_WIDTH) + 1)
  #define DYNTICK_TASK_NEST_MASK  (LLONG_MAX - DYNTICK_TASK_NEST_VALUE + 1)
  #define DYNTICK_TASK_FLAG	   ((DYNTICK_TASK_NEST_VALUE / 8) * 2)
  #define DYNTICK_TASK_MASK	   ((DYNTICK_TASK_NEST_VALUE / 8) * 3)
  #define DYNTICK_TASK_EXIT_IDLE	   (DYNTICK_TASK_NEST_VALUE + \
  				    DYNTICK_TASK_FLAG)

  
  /*

   * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
   * by call_rcu() and rcu callback execution, and are therefore not part of the
   * RCU API. Leaving in rcupdate.h because they are used by all RCU flavors.
   */
  
  #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
  # define STATE_RCU_HEAD_READY	0
  # define STATE_RCU_HEAD_QUEUED	1
  
  extern struct debug_obj_descr rcuhead_debug_descr;
  
  static inline void debug_rcu_head_queue(struct rcu_head *head)
  {

  	debug_object_activate(head, &rcuhead_debug_descr);
  	debug_object_active_state(head, &rcuhead_debug_descr,
  				  STATE_RCU_HEAD_READY,
  				  STATE_RCU_HEAD_QUEUED);
  }
  
  static inline void debug_rcu_head_unqueue(struct rcu_head *head)
  {
  	debug_object_active_state(head, &rcuhead_debug_descr,
  				  STATE_RCU_HEAD_QUEUED,
  				  STATE_RCU_HEAD_READY);
  	debug_object_deactivate(head, &rcuhead_debug_descr);
  }
  #else	/* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
  static inline void debug_rcu_head_queue(struct rcu_head *head)
  {
  }
  
  static inline void debug_rcu_head_unqueue(struct rcu_head *head)
  {
  }
  #endif	/* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
  
  extern void kfree(const void *);

  static inline bool __rcu_reclaim(char *rn, struct rcu_head *head)

  {
  	unsigned long offset = (unsigned long)head->func;
  
  	if (__is_kfree_rcu_offset(offset)) {

  		RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset));

  		kfree((void *)head - offset);

  		return 1;

  	} else {

  		RCU_TRACE(trace_rcu_invoke_callback(rn, head));

  		head->func(head);

  		return 0;

  	}
  }

  extern int rcu_expedited;

  #ifdef CONFIG_RCU_STALL_COMMON
  
  extern int rcu_cpu_stall_suppress;
  int rcu_jiffies_till_stall_check(void);
  
  #endif /* #ifdef CONFIG_RCU_STALL_COMMON */

  #endif /* __LINUX_RCU_H */