[linux-2.6-block.git] / kernel / rcutree.h

/*
 * Read-Copy Update mechanism for mutual exclusion (tree-based version)
 * Internal non-public definitions.
 *
 * 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, 2008
 *
 * Author: Ingo Molnar <mingo@elte.hu>
 *	   Paul E. McKenney <paulmck@linux.vnet.ibm.com>
 */

#include <linux/cache.h>
#include <linux/spinlock.h>
#include <linux/threads.h>
#include <linux/cpumask.h>
#include <linux/seqlock.h>

/*
 * Define shape of hierarchy based on NR_CPUS and CONFIG_RCU_FANOUT.
 * In theory, it should be possible to add more levels straightforwardly.
 * In practice, this has not been tested, so there is probably some
 * bug somewhere.
 */
#define MAX_RCU_LVLS 3
#define RCU_FANOUT	      (CONFIG_RCU_FANOUT)
#define RCU_FANOUT_SQ	      (RCU_FANOUT * RCU_FANOUT)
#define RCU_FANOUT_CUBE	      (RCU_FANOUT_SQ * RCU_FANOUT)

#if NR_CPUS <= RCU_FANOUT
#  define NUM_RCU_LVLS	      1
#  define NUM_RCU_LVL_0	      1
#  define NUM_RCU_LVL_1	      (NR_CPUS)
#  define NUM_RCU_LVL_2	      0
#  define NUM_RCU_LVL_3	      0
#elif NR_CPUS <= RCU_FANOUT_SQ
#  define NUM_RCU_LVLS	      2
#  define NUM_RCU_LVL_0	      1
#  define NUM_RCU_LVL_1	      (((NR_CPUS) + RCU_FANOUT - 1) / RCU_FANOUT)
#  define NUM_RCU_LVL_2	      (NR_CPUS)
#  define NUM_RCU_LVL_3	      0
#elif NR_CPUS <= RCU_FANOUT_CUBE
#  define NUM_RCU_LVLS	      3
#  define NUM_RCU_LVL_0	      1
#  define NUM_RCU_LVL_1	      (((NR_CPUS) + RCU_FANOUT_SQ - 1) / RCU_FANOUT_SQ)
#  define NUM_RCU_LVL_2	      (((NR_CPUS) + (RCU_FANOUT) - 1) / (RCU_FANOUT))
#  define NUM_RCU_LVL_3	      NR_CPUS
#else
# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
#endif /* #if (NR_CPUS) <= RCU_FANOUT */

#define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3)
#define NUM_RCU_NODES (RCU_SUM - NR_CPUS)

/*
 * Dynticks per-CPU state.
 */
struct rcu_dynticks {
	int dynticks_nesting;	/* Track nesting level, sort of. */
	int dynticks;		/* Even value for dynticks-idle, else odd. */
	int dynticks_nmi;	/* Even value for either dynticks-idle or */
				/*  not in nmi handler, else odd.  So this */
				/*  remains even for nmi from irq handler. */
};

/*
 * Definition for node within the RCU grace-period-detection hierarchy.
 */
struct rcu_node {
	spinlock_t lock;
	long	gpnum;		/* Current grace period for this node. */
	unsigned long qsmask;	/* CPUs or groups that need to switch in */
				/*  order for current grace period to proceed.*/
	unsigned long qsmaskinit;
				/* Per-GP initialization for qsmask. */
	unsigned long grpmask;	/* Mask to apply to parent qsmask. */
	int	grplo;		/* lowest-numbered CPU or group here. */
	int	grphi;		/* highest-numbered CPU or group here. */
	u8	grpnum;		/* CPU/group number for next level up. */
	u8	level;		/* root is at level 0. */
	struct rcu_node *parent;
	struct list_head blocked_tasks[2];
				/* Tasks blocked in RCU read-side critsect. */
} ____cacheline_internodealigned_in_smp;

/* Index values for nxttail array in struct rcu_data. */
#define RCU_DONE_TAIL		0	/* Also RCU_WAIT head. */
#define RCU_WAIT_TAIL		1	/* Also RCU_NEXT_READY head. */
#define RCU_NEXT_READY_TAIL	2	/* Also RCU_NEXT head. */
#define RCU_NEXT_TAIL		3
#define RCU_NEXT_SIZE		4

/* Per-CPU data for read-copy update. */
struct rcu_data {
	/* 1) quiescent-state and grace-period handling : */
	long		completed;	/* Track rsp->completed gp number */
					/*  in order to detect GP end. */
	long		gpnum;		/* Highest gp number that this CPU */
					/*  is aware of having started. */
	long		passed_quiesc_completed;
					/* Value of completed at time of qs. */
	bool		passed_quiesc;	/* User-mode/idle loop etc. */
	bool		qs_pending;	/* Core waits for quiesc state. */
	bool		beenonline;	/* CPU online at least once. */
	bool		preemptable;	/* Preemptable RCU? */
	struct rcu_node *mynode;	/* This CPU's leaf of hierarchy */
	unsigned long grpmask;		/* Mask to apply to leaf qsmask. */

	/* 2) batch handling */
	/*
	 * If nxtlist is not NULL, it is partitioned as follows.
	 * Any of the partitions might be empty, in which case the
	 * pointer to that partition will be equal to the pointer for
	 * the following partition.  When the list is empty, all of
	 * the nxttail elements point to nxtlist, which is NULL.
	 *
	 * [*nxttail[RCU_NEXT_READY_TAIL], NULL = *nxttail[RCU_NEXT_TAIL]):
	 *	Entries that might have arrived after current GP ended
	 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]):
	 *	Entries known to have arrived before current GP ended
	 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]):
	 *	Entries that batch # <= ->completed - 1: waiting for current GP
	 * [nxtlist, *nxttail[RCU_DONE_TAIL]):
	 *	Entries that batch # <= ->completed
	 *	The grace period for these entries has completed, and
	 *	the other grace-period-completed entries may be moved
	 *	here temporarily in rcu_process_callbacks().
	 */
	struct rcu_head *nxtlist;
	struct rcu_head **nxttail[RCU_NEXT_SIZE];
	long		qlen; 	 	/* # of queued callbacks */
	long		blimit;		/* Upper limit on a processed batch */

#ifdef CONFIG_NO_HZ
	/* 3) dynticks interface. */
	struct rcu_dynticks *dynticks;	/* Shared per-CPU dynticks state. */
	int dynticks_snap;		/* Per-GP tracking for dynticks. */
	int dynticks_nmi_snap;		/* Per-GP tracking for dynticks_nmi. */
#endif /* #ifdef CONFIG_NO_HZ */

	/* 4) reasons this CPU needed to be kicked by force_quiescent_state */
#ifdef CONFIG_NO_HZ
	unsigned long dynticks_fqs;	/* Kicked due to dynticks idle. */
#endif /* #ifdef CONFIG_NO_HZ */
	unsigned long offline_fqs;	/* Kicked due to being offline. */
	unsigned long resched_ipi;	/* Sent a resched IPI. */

	/* 5) __rcu_pending() statistics. */
	long n_rcu_pending;		/* rcu_pending() calls since boot. */
	long n_rp_qs_pending;
	long n_rp_cb_ready;
	long n_rp_cpu_needs_gp;
	long n_rp_gp_completed;
	long n_rp_gp_started;
	long n_rp_need_fqs;
	long n_rp_need_nothing;

	int cpu;
};

/* Values for signaled field in struct rcu_state. */
#define RCU_GP_INIT		0	/* Grace period being initialized. */
#define RCU_SAVE_DYNTICK	1	/* Need to scan dyntick state. */
#define RCU_FORCE_QS		2	/* Need to force quiescent state. */
#ifdef CONFIG_NO_HZ
#define RCU_SIGNAL_INIT		RCU_SAVE_DYNTICK
#else /* #ifdef CONFIG_NO_HZ */
#define RCU_SIGNAL_INIT		RCU_FORCE_QS
#endif /* #else #ifdef CONFIG_NO_HZ */

#define RCU_JIFFIES_TILL_FORCE_QS	 3	/* for rsp->jiffies_force_qs */
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
#define RCU_SECONDS_TILL_STALL_CHECK   (10 * HZ)  /* for rsp->jiffies_stall */
#define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ)  /* for rsp->jiffies_stall */
#define RCU_STALL_RAT_DELAY		2	  /* Allow other CPUs time */
						  /*  to take at least one */
						  /*  scheduling clock irq */
						  /*  before ratting on them. */

#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */

/*
 * RCU global state, including node hierarchy.  This hierarchy is
 * represented in "heap" form in a dense array.  The root (first level)
 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
 * and the third level in ->node[m+1] and following (->node[m+1] referenced
 * by ->level[2]).  The number of levels is determined by the number of
 * CPUs and by CONFIG_RCU_FANOUT.  Small systems will have a "hierarchy"
 * consisting of a single rcu_node.
 */
struct rcu_state {
	struct rcu_node node[NUM_RCU_NODES];	/* Hierarchy. */
	struct rcu_node *level[NUM_RCU_LVLS];	/* Hierarchy levels. */
	u32 levelcnt[MAX_RCU_LVLS + 1];		/* # nodes in each level. */
	u8 levelspread[NUM_RCU_LVLS];		/* kids/node in each level. */
	struct rcu_data *rda[NR_CPUS];		/* array of rdp pointers. */

	/* The following fields are guarded by the root rcu_node's lock. */

	u8	signaled ____cacheline_internodealigned_in_smp;
						/* Force QS state. */
	long	gpnum;				/* Current gp number. */
	long	completed;			/* # of last completed gp. */
	spinlock_t onofflock;			/* exclude on/offline and */
						/*  starting new GP. */
	spinlock_t fqslock;			/* Only one task forcing */
						/*  quiescent states. */
	unsigned long jiffies_force_qs;		/* Time at which to invoke */
						/*  force_quiescent_state(). */
	unsigned long n_force_qs;		/* Number of calls to */
						/*  force_quiescent_state(). */
	unsigned long n_force_qs_lh;		/* ~Number of calls leaving */
						/*  due to lock unavailable. */
	unsigned long n_force_qs_ngp;		/* Number of calls leaving */
						/*  due to no GP active. */
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
	unsigned long gp_start;			/* Time at which GP started, */
						/*  but in jiffies. */
	unsigned long jiffies_stall;		/* Time at which to check */
						/*  for CPU stalls. */
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
#ifdef CONFIG_NO_HZ
	long dynticks_completed;		/* Value of completed @ snap. */
#endif /* #ifdef CONFIG_NO_HZ */
};

#ifdef RCU_TREE_NONCORE

/*
 * RCU implementation internal declarations:
 */
extern struct rcu_state rcu_sched_state;
DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);

extern struct rcu_state rcu_bh_state;
DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);

#ifdef CONFIG_TREE_PREEMPT_RCU
extern struct rcu_state rcu_preempt_state;
DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */

#endif /* #ifdef RCU_TREE_NONCORE */
Commit	Line	Data
9f77da9f PM	1	/*
	2	* Read-Copy Update mechanism for mutual exclusion (tree-based version)
	3	* Internal non-public definitions.
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation; either version 2 of the License, or
	8	* (at your option) any later version.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*
	15	* You should have received a copy of the GNU General Public License
	16	* along with this program; if not, write to the Free Software
	17	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	18	*
	19	* Copyright IBM Corporation, 2008
	20	*
	21	* Author: Ingo Molnar <mingo@elte.hu>
	22	* Paul E. McKenney <paulmck@linux.vnet.ibm.com>
	23	*/
	24
	25	#include <linux/cache.h>
	26	#include <linux/spinlock.h>
	27	#include <linux/threads.h>
	28	#include <linux/cpumask.h>
	29	#include <linux/seqlock.h>
	30
	31	/*
	32	* Define shape of hierarchy based on NR_CPUS and CONFIG_RCU_FANOUT.
	33	* In theory, it should be possible to add more levels straightforwardly.
	34	* In practice, this has not been tested, so there is probably some
	35	* bug somewhere.
	36	*/
	37	#define MAX_RCU_LVLS 3
	38	#define RCU_FANOUT (CONFIG_RCU_FANOUT)
	39	#define RCU_FANOUT_SQ (RCU_FANOUT * RCU_FANOUT)
	40	#define RCU_FANOUT_CUBE (RCU_FANOUT_SQ * RCU_FANOUT)
	41
	42	#if NR_CPUS <= RCU_FANOUT
	43	# define NUM_RCU_LVLS 1
	44	# define NUM_RCU_LVL_0 1
	45	# define NUM_RCU_LVL_1 (NR_CPUS)
	46	# define NUM_RCU_LVL_2 0
	47	# define NUM_RCU_LVL_3 0
	48	#elif NR_CPUS <= RCU_FANOUT_SQ
	49	# define NUM_RCU_LVLS 2
	50	# define NUM_RCU_LVL_0 1
	51	# define NUM_RCU_LVL_1 (((NR_CPUS) + RCU_FANOUT - 1) / RCU_FANOUT)
	52	# define NUM_RCU_LVL_2 (NR_CPUS)
	53	# define NUM_RCU_LVL_3 0
	54	#elif NR_CPUS <= RCU_FANOUT_CUBE
	55	# define NUM_RCU_LVLS 3
	56	# define NUM_RCU_LVL_0 1
	57	# define NUM_RCU_LVL_1 (((NR_CPUS) + RCU_FANOUT_SQ - 1) / RCU_FANOUT_SQ)
	58	# define NUM_RCU_LVL_2 (((NR_CPUS) + (RCU_FANOUT) - 1) / (RCU_FANOUT))
	59	# define NUM_RCU_LVL_3 NR_CPUS
	60	#else
	61	# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
	62	#endif /* #if (NR_CPUS) <= RCU_FANOUT */
	63
	64	#define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3)
65	#define NUM_RCU_NODES (RCU_SUM - NR_CPUS)
66
67	/*
68	* Dynticks per-CPU state.
69	*/
70	struct rcu_dynticks {
71	int dynticks_nesting; /* Track nesting level, sort of. */
72	int dynticks; /* Even value for dynticks-idle, else odd. */
73	int dynticks_nmi; /* Even value for either dynticks-idle or */
74	/* not in nmi handler, else odd. So this */
75	/* remains even for nmi from irq handler. */
76	};
77
78	/*
79	* Definition for node within the RCU grace-period-detection hierarchy.
80	*/
81	struct rcu_node {
82	spinlock_t lock;
f41d911f	83	long gpnum; /* Current grace period for this node. */
9f77da9f PM	84	unsigned long qsmask; /* CPUs or groups that need to switch in */
	85	/* order for current grace period to proceed.*/
	86	unsigned long qsmaskinit;
	87	/* Per-GP initialization for qsmask. */
	88	unsigned long grpmask; /* Mask to apply to parent qsmask. */
	89	int grplo; /* lowest-numbered CPU or group here. */
	90	int grphi; /* highest-numbered CPU or group here. */
	91	u8 grpnum; /* CPU/group number for next level up. */
	92	u8 level; /* root is at level 0. */
	93	struct rcu_node *parent;
f41d911f PM	94	struct list_head blocked_tasks[2];
f41d911f PM	95	/* Tasks blocked in RCU read-side critsect. */
9f77da9f PM	96	} ____cacheline_internodealigned_in_smp;
	97
	98	/* Index values for nxttail array in struct rcu_data. */
	99	#define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */
	100	#define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */
	101	#define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */
	102	#define RCU_NEXT_TAIL 3
	103	#define RCU_NEXT_SIZE 4
	104
	105	/* Per-CPU data for read-copy update. */
	106	struct rcu_data {
	107	/* 1) quiescent-state and grace-period handling : */
	108	long completed; /* Track rsp->completed gp number */
	109	/* in order to detect GP end. */
	110	long gpnum; /* Highest gp number that this CPU */
	111	/* is aware of having started. */
	112	long passed_quiesc_completed;
	113	/* Value of completed at time of qs. */
	114	bool passed_quiesc; /* User-mode/idle loop etc. */
	115	bool qs_pending; /* Core waits for quiesc state. */
	116	bool beenonline; /* CPU online at least once. */
f41d911f	117	bool preemptable; /* Preemptable RCU? */
9f77da9f PM	118	struct rcu_node mynode; / This CPU's leaf of hierarchy */
	119	unsigned long grpmask; /* Mask to apply to leaf qsmask. */
	120
	121	/* 2) batch handling */
	122	/*
	123	* If nxtlist is not NULL, it is partitioned as follows.
	124	* Any of the partitions might be empty, in which case the
	125	* pointer to that partition will be equal to the pointer for
	126	* the following partition. When the list is empty, all of
	127	* the nxttail elements point to nxtlist, which is NULL.
	128	*
	129	* [nxttail[RCU_NEXT_READY_TAIL], NULL = nxttail[RCU_NEXT_TAIL]):
	130	* Entries that might have arrived after current GP ended
	131	* [nxttail[RCU_WAIT_TAIL], nxttail[RCU_NEXT_READY_TAIL]):
	132	* Entries known to have arrived before current GP ended
	133	* [nxttail[RCU_DONE_TAIL], nxttail[RCU_WAIT_TAIL]):
	134	* Entries that batch # <= ->completed - 1: waiting for current GP
	135	* [nxtlist, *nxttail[RCU_DONE_TAIL]):
	136	* Entries that batch # <= ->completed
	137	* The grace period for these entries has completed, and
	138	* the other grace-period-completed entries may be moved
	139	* here temporarily in rcu_process_callbacks().
	140	*/
	141	struct rcu_head *nxtlist;
	142	struct rcu_head **nxttail[RCU_NEXT_SIZE];
	143	long qlen; /* # of queued callbacks */
	144	long blimit; /* Upper limit on a processed batch */
	145
	146	#ifdef CONFIG_NO_HZ
	147	/* 3) dynticks interface. */
	148	struct rcu_dynticks dynticks; / Shared per-CPU dynticks state. */
	149	int dynticks_snap; /* Per-GP tracking for dynticks. */
	150	int dynticks_nmi_snap; /* Per-GP tracking for dynticks_nmi. */
	151	#endif /* #ifdef CONFIG_NO_HZ */
	152
	153	/* 4) reasons this CPU needed to be kicked by force_quiescent_state */
	154	#ifdef CONFIG_NO_HZ
	155	unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
	156	#endif /* #ifdef CONFIG_NO_HZ */
	157	unsigned long offline_fqs; /* Kicked due to being offline. */
	158	unsigned long resched_ipi; /* Sent a resched IPI. */
	159
	160	/* 5) __rcu_pending() statistics. */
	161	long n_rcu_pending; /* rcu_pending() calls since boot. */
	162	long n_rp_qs_pending;
	163	long n_rp_cb_ready;
	164	long n_rp_cpu_needs_gp;
	165	long n_rp_gp_completed;
	166	long n_rp_gp_started;
	167	long n_rp_need_fqs;
	168	long n_rp_need_nothing;
	169
	170	int cpu;
	171	};
	172
	173	/* Values for signaled field in struct rcu_state. */
	174	#define RCU_GP_INIT 0 /* Grace period being initialized. */
	175	#define RCU_SAVE_DYNTICK 1 /* Need to scan dyntick state. */
	176	#define RCU_FORCE_QS 2 /* Need to force quiescent state. */
	177	#ifdef CONFIG_NO_HZ
	178	#define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK
	179	#else /* #ifdef CONFIG_NO_HZ */
	180	#define RCU_SIGNAL_INIT RCU_FORCE_QS
	181	#endif /* #else #ifdef CONFIG_NO_HZ */
182
183	#define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */
184	#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
185	#define RCU_SECONDS_TILL_STALL_CHECK (10 * HZ) /* for rsp->jiffies_stall */
186	#define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ) /* for rsp->jiffies_stall */
187	#define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time */
188	/* to take at least one */
189	/* scheduling clock irq */
190	/* before ratting on them. */
191
192	#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
193
194	/*
195	* RCU global state, including node hierarchy. This hierarchy is
196	* represented in "heap" form in a dense array. The root (first level)
197	* of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
198	* level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
199	* and the third level in ->node[m+1] and following (->node[m+1] referenced
200	* by ->level[2]). The number of levels is determined by the number of
201	* CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy"
202	* consisting of a single rcu_node.
203	*/
204	struct rcu_state {
205	struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
206	struct rcu_node level[NUM_RCU_LVLS]; / Hierarchy levels. */
207	u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
208	u8 levelspread[NUM_RCU_LVLS]; /* kids/node in each level. */
209	struct rcu_data rda[NR_CPUS]; / array of rdp pointers. */
210
211	/* The following fields are guarded by the root rcu_node's lock. */
212
213	u8 signaled ____cacheline_internodealigned_in_smp;
214	/* Force QS state. */
215	long gpnum; /* Current gp number. */
216	long completed; /* # of last completed gp. */
217	spinlock_t onofflock; /* exclude on/offline and */
218	/* starting new GP. */
219	spinlock_t fqslock; /* Only one task forcing */
220	/* quiescent states. */
221	unsigned long jiffies_force_qs; /* Time at which to invoke */
222	/* force_quiescent_state(). */
223	unsigned long n_force_qs; /* Number of calls to */
224	/* force_quiescent_state(). */
225	unsigned long n_force_qs_lh; /* ~Number of calls leaving */
226	/* due to lock unavailable. */
227	unsigned long n_force_qs_ngp; /* Number of calls leaving */
228	/* due to no GP active. */
229	#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
230	unsigned long gp_start; /* Time at which GP started, */
231	/* but in jiffies. */
232	unsigned long jiffies_stall; /* Time at which to check */
233	/* for CPU stalls. */
234	#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
235	#ifdef CONFIG_NO_HZ
236	long dynticks_completed; /* Value of completed @ snap. */
237	#endif /* #ifdef CONFIG_NO_HZ */
238	};
239
240	#ifdef RCU_TREE_NONCORE
6258c4fb IM	241
	242	/*
	243	* RCU implementation internal declarations:
	244	*/
d6714c22 PM	245	extern struct rcu_state rcu_sched_state;
d6714c22 PM	246	DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
6258c4fb IM	247
	248	extern struct rcu_state rcu_bh_state;
	249	DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
	250
f41d911f PM	251	#ifdef CONFIG_TREE_PREEMPT_RCU
	252	extern struct rcu_state rcu_preempt_state;
	253	DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
	254	#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
	255
9f77da9f PM	256	#endif /* #ifdef RCU_TREE_NONCORE */
9f77da9f PM	257