1 files changed, 251 insertions, 2 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 5e872bbf07f5..bf8a6f9f134d 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -1,10 +1,259 @@
+/*
+ * 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. */
+                                /*  This will either be equal to or one */
+                                /*  behind the root rcu_node's gpnum. */
+        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_state;
+extern struct rcu_state rcu_sched_state;
-DECLARE_PER_CPU(struct rcu_data, rcu_data);
+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 */

diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 5e872bbf07f5..bf8a6f9f134d 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h
@@ -1,10 +1,259 @@
		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;
		83	long gpnum; /* Current grace period for this node. */
		84	/* This will either be equal to or one */
		85	/* behind the root rcu_node's gpnum. */
		86	unsigned long qsmask; /* CPUs or groups that need to switch in */
		87	/* order for current grace period to proceed.*/
		88	unsigned long qsmaskinit;
		89	/* Per-GP initialization for qsmask. */
		90	unsigned long grpmask; /* Mask to apply to parent qsmask. */
		91	int grplo; /* lowest-numbered CPU or group here. */
		92	int grphi; /* highest-numbered CPU or group here. */
		93	u8 grpnum; /* CPU/group number for next level up. */
		94	u8 level; /* root is at level 0. */
		95	struct rcu_node *parent;
		96	struct list_head blocked_tasks[2];
		97	/* Tasks blocked in RCU read-side critsect. */
		98	} ____cacheline_internodealigned_in_smp;
		99
		100	/* Index values for nxttail array in struct rcu_data. */
		101	#define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */
		102	#define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */
		103	#define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */
		104	#define RCU_NEXT_TAIL 3
		105	#define RCU_NEXT_SIZE 4
		106
		107	/* Per-CPU data for read-copy update. */
		108	struct rcu_data {
		109	/* 1) quiescent-state and grace-period handling : */
		110	long completed; /* Track rsp->completed gp number */
		111	/* in order to detect GP end. */
		112	long gpnum; /* Highest gp number that this CPU */
		113	/* is aware of having started. */
		114	long passed_quiesc_completed;
		115	/* Value of completed at time of qs. */
		116	bool passed_quiesc; /* User-mode/idle loop etc. */
		117	bool qs_pending; /* Core waits for quiesc state. */
		118	bool beenonline; /* CPU online at least once. */
		119	bool preemptable; /* Preemptable RCU? */
		120	struct rcu_node mynode; / This CPU's leaf of hierarchy */
		121	unsigned long grpmask; /* Mask to apply to leaf qsmask. */
		122
		123	/* 2) batch handling */
		124	/*
		125	* If nxtlist is not NULL, it is partitioned as follows.
		126	* Any of the partitions might be empty, in which case the
		127	* pointer to that partition will be equal to the pointer for
		128	* the following partition. When the list is empty, all of
		129	* the nxttail elements point to nxtlist, which is NULL.
		130	*
		131	* [nxttail[RCU_NEXT_READY_TAIL], NULL = nxttail[RCU_NEXT_TAIL]):
		132	* Entries that might have arrived after current GP ended
		133	* [nxttail[RCU_WAIT_TAIL], nxttail[RCU_NEXT_READY_TAIL]):
		134	* Entries known to have arrived before current GP ended
		135	* [nxttail[RCU_DONE_TAIL], nxttail[RCU_WAIT_TAIL]):
		136	* Entries that batch # <= ->completed - 1: waiting for current GP
		137	* [nxtlist, *nxttail[RCU_DONE_TAIL]):
		138	* Entries that batch # <= ->completed
		139	* The grace period for these entries has completed, and
		140	* the other grace-period-completed entries may be moved
		141	* here temporarily in rcu_process_callbacks().
		142	*/
		143	struct rcu_head *nxtlist;
		144	struct rcu_head **nxttail[RCU_NEXT_SIZE];
		145	long qlen; /* # of queued callbacks */
		146	long blimit; /* Upper limit on a processed batch */
		147
		148	#ifdef CONFIG_NO_HZ
		149	/* 3) dynticks interface. */
		150	struct rcu_dynticks dynticks; / Shared per-CPU dynticks state. */
		151	int dynticks_snap; /* Per-GP tracking for dynticks. */
		152	int dynticks_nmi_snap; /* Per-GP tracking for dynticks_nmi. */
		153	#endif /* #ifdef CONFIG_NO_HZ */
		154
		155	/* 4) reasons this CPU needed to be kicked by force_quiescent_state */
		156	#ifdef CONFIG_NO_HZ
		157	unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
		158	#endif /* #ifdef CONFIG_NO_HZ */
		159	unsigned long offline_fqs; /* Kicked due to being offline. */
		160	unsigned long resched_ipi; /* Sent a resched IPI. */
		161
		162	/* 5) __rcu_pending() statistics. */
		163	long n_rcu_pending; /* rcu_pending() calls since boot. */
		164	long n_rp_qs_pending;
		165	long n_rp_cb_ready;
		166	long n_rp_cpu_needs_gp;
		167	long n_rp_gp_completed;
		168	long n_rp_gp_started;
		169	long n_rp_need_fqs;
		170	long n_rp_need_nothing;
		171
		172	int cpu;
		173	};
		174
		175	/* Values for signaled field in struct rcu_state. */
		176	#define RCU_GP_INIT 0 /* Grace period being initialized. */
		177	#define RCU_SAVE_DYNTICK 1 /* Need to scan dyntick state. */
		178	#define RCU_FORCE_QS 2 /* Need to force quiescent state. */
		179	#ifdef CONFIG_NO_HZ
		180	#define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK
		181	#else /* #ifdef CONFIG_NO_HZ */
		182	#define RCU_SIGNAL_INIT RCU_FORCE_QS
		183	#endif /* #else #ifdef CONFIG_NO_HZ */
		184
		185	#define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */
		186	#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
		187	#define RCU_SECONDS_TILL_STALL_CHECK (10 * HZ) /* for rsp->jiffies_stall */
		188	#define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ) /* for rsp->jiffies_stall */
		189	#define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time */
		190	/* to take at least one */
		191	/* scheduling clock irq */
		192	/* before ratting on them. */
		193
		194	#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
		195
		196	/*
		197	* RCU global state, including node hierarchy. This hierarchy is
		198	* represented in "heap" form in a dense array. The root (first level)
		199	* of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
		200	* level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
		201	* and the third level in ->node[m+1] and following (->node[m+1] referenced
		202	* by ->level[2]). The number of levels is determined by the number of
		203	* CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy"
		204	* consisting of a single rcu_node.
		205	*/
		206	struct rcu_state {
		207	struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
		208	struct rcu_node level[NUM_RCU_LVLS]; / Hierarchy levels. */
		209	u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
		210	u8 levelspread[NUM_RCU_LVLS]; /* kids/node in each level. */
		211	struct rcu_data rda[NR_CPUS]; / array of rdp pointers. */
		212
		213	/* The following fields are guarded by the root rcu_node's lock. */
		214
		215	u8 signaled ____cacheline_internodealigned_in_smp;
		216	/* Force QS state. */
		217	long gpnum; /* Current gp number. */
		218	long completed; /* # of last completed gp. */
		219	spinlock_t onofflock; /* exclude on/offline and */
		220	/* starting new GP. */
		221	spinlock_t fqslock; /* Only one task forcing */
		222	/* quiescent states. */
		223	unsigned long jiffies_force_qs; /* Time at which to invoke */
		224	/* force_quiescent_state(). */
		225	unsigned long n_force_qs; /* Number of calls to */
		226	/* force_quiescent_state(). */
		227	unsigned long n_force_qs_lh; /* ~Number of calls leaving */
		228	/* due to lock unavailable. */
		229	unsigned long n_force_qs_ngp; /* Number of calls leaving */
		230	/* due to no GP active. */
		231	#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
		232	unsigned long gp_start; /* Time at which GP started, */
		233	/* but in jiffies. */
		234	unsigned long jiffies_stall; /* Time at which to check */
		235	/* for CPU stalls. */
		236	#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
		237	#ifdef CONFIG_NO_HZ
		238	long dynticks_completed; /* Value of completed @ snap. */
		239	#endif /* #ifdef CONFIG_NO_HZ */
		240	};
		241
		242	#ifdef RCU_TREE_NONCORE
1		243
2	/*	244	/*
3	* RCU implementation internal declarations:	245	* RCU implementation internal declarations:
4	*/	246	*/
5	extern struct rcu_state rcu_state;	247	extern struct rcu_state rcu_sched_state;
6	DECLARE_PER_CPU(struct rcu_data, rcu_data);	248	DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
7		249
8	extern struct rcu_state rcu_bh_state;	250	extern struct rcu_state rcu_bh_state;
9	DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);	251	DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
10		252
		253	#ifdef CONFIG_TREE_PREEMPT_RCU
		254	extern struct rcu_state rcu_preempt_state;
		255	DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
		256	#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
		257
		258	#endif /* #ifdef RCU_TREE_NONCORE */
		259