/* * 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;	}} #endif /* __LINUX_RCU_H */