* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
*
* For detailed explanation of Read-Copy Update mechanism see -
- * Documentation/RCU
+ * Documentation/RCU
*/
#ifndef __LINUX_RCUTREE_H
#define __LINUX_RCUTREE_H
-#include <linux/cache.h>
-#include <linux/spinlock.h>
-#include <linux/threads.h>
-#include <linux/percpu.h>
-#include <linux/cpumask.h>
-#include <linux/seqlock.h>
+struct notifier_block;
-/*
- * 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;
- 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;
-} ____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. */
- 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) state to allow this CPU to force_quiescent_state on others */
- long n_rcu_pending; /* rcu_pending() calls since boot. */
- long n_rcu_pending_force_qs; /* when to force quiescent states. */
-
- 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 */
+extern void rcu_sched_qs(int cpu);
+extern void rcu_bh_qs(int cpu);
+extern void rcu_note_context_switch(int cpu);
+extern int rcu_needs_cpu(int cpu);
-#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. */
+#ifdef CONFIG_TREE_PREEMPT_RCU
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+extern void __rcu_read_lock(void);
+extern void __rcu_read_unlock(void);
+extern void synchronize_rcu(void);
+extern void exit_rcu(void);
/*
- * 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.
+ * Defined as macro as it is a very low level header
+ * included from areas that don't even know about current
*/
-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. */
+#define rcu_preempt_depth() (current->rcu_read_lock_nesting)
- /* The following fields are guarded by the root rcu_node's lock. */
+#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
- 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 */
-};
-
-extern struct rcu_state rcu_state;
-DECLARE_PER_CPU(struct rcu_data, rcu_data);
-
-extern struct rcu_state rcu_bh_state;
-DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
-
-/*
- * Increment the quiescent state counter.
- * The counter is a bit degenerated: We do not need to know
- * how many quiescent states passed, just if there was at least
- * one since the start of the grace period. Thus just a flag.
- */
-static inline void rcu_qsctr_inc(int cpu)
+static inline void __rcu_read_lock(void)
{
- struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
- rdp->passed_quiesc = 1;
- rdp->passed_quiesc_completed = rdp->completed;
+ preempt_disable();
}
-static inline void rcu_bh_qsctr_inc(int cpu)
+
+static inline void __rcu_read_unlock(void)
{
- struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
- rdp->passed_quiesc = 1;
- rdp->passed_quiesc_completed = rdp->completed;
+ preempt_enable();
}
-extern int rcu_pending(int cpu);
-extern int rcu_needs_cpu(int cpu);
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-extern struct lockdep_map rcu_lock_map;
-# define rcu_read_acquire() \
- lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
-# define rcu_read_release() lock_release(&rcu_lock_map, 1, _THIS_IP_)
-#else
-# define rcu_read_acquire() do { } while (0)
-# define rcu_read_release() do { } while (0)
-#endif
+#define synchronize_rcu synchronize_sched
-static inline void __rcu_read_lock(void)
+static inline void exit_rcu(void)
{
- preempt_disable();
- __acquire(RCU);
- rcu_read_acquire();
}
-static inline void __rcu_read_unlock(void)
+
+static inline int rcu_preempt_depth(void)
{
- rcu_read_release();
- __release(RCU);
- preempt_enable();
+ return 0;
}
+
+#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
+
static inline void __rcu_read_lock_bh(void)
{
local_bh_disable();
- __acquire(RCU_BH);
- rcu_read_acquire();
}
static inline void __rcu_read_unlock_bh(void)
{
- rcu_read_release();
- __release(RCU_BH);
local_bh_enable();
}
-#define __synchronize_sched() synchronize_rcu()
+extern void call_rcu_sched(struct rcu_head *head,
+ void (*func)(struct rcu_head *rcu));
+extern void synchronize_rcu_bh(void);
+extern void synchronize_sched(void);
+extern void synchronize_rcu_expedited(void);
-#define call_rcu_sched(head, func) call_rcu(head, func)
-
-static inline void rcu_init_sched(void)
+static inline void synchronize_rcu_bh_expedited(void)
{
+ synchronize_sched_expedited();
}
-extern void __rcu_init(void);
extern void rcu_check_callbacks(int cpu, int user);
-extern void rcu_restart_cpu(int cpu);
extern long rcu_batches_completed(void);
extern long rcu_batches_completed_bh(void);
+extern long rcu_batches_completed_sched(void);
+extern void rcu_force_quiescent_state(void);
+extern void rcu_bh_force_quiescent_state(void);
+extern void rcu_sched_force_quiescent_state(void);
#ifdef CONFIG_NO_HZ
void rcu_enter_nohz(void);
}
#endif /* CONFIG_NO_HZ */
-/* A context switch is a grace period for rcutree. */
+/* A context switch is a grace period for RCU-sched and RCU-bh. */
static inline int rcu_blocking_is_gp(void)
{
return num_online_cpus() == 1;
}
+extern void rcu_scheduler_starting(void);
+extern int rcu_scheduler_active __read_mostly;
+
#endif /* __LINUX_RCUTREE_H */
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff