260 lines
9.8 KiB
C
260 lines
9.8 KiB
C
/*
|
|
* 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_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 */
|
|
|