742 строки
29 KiB
C
742 строки
29 KiB
C
/*
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* Read-Copy Update mechanism for mutual exclusion (tree-based version)
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* Internal non-public definitions.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you can access it online at
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* http://www.gnu.org/licenses/gpl-2.0.html.
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*
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* Copyright IBM Corporation, 2008
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*
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* Author: Ingo Molnar <mingo@elte.hu>
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* Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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*/
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#include <linux/cache.h>
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#include <linux/spinlock.h>
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#include <linux/threads.h>
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#include <linux/cpumask.h>
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#include <linux/seqlock.h>
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#include <linux/swait.h>
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#include <linux/stop_machine.h>
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/*
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* Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
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* CONFIG_RCU_FANOUT_LEAF.
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* In theory, it should be possible to add more levels straightforwardly.
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* In practice, this did work well going from three levels to four.
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* Of course, your mileage may vary.
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*/
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#ifdef CONFIG_RCU_FANOUT
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#define RCU_FANOUT CONFIG_RCU_FANOUT
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#else /* #ifdef CONFIG_RCU_FANOUT */
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# ifdef CONFIG_64BIT
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# define RCU_FANOUT 64
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# else
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# define RCU_FANOUT 32
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# endif
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#endif /* #else #ifdef CONFIG_RCU_FANOUT */
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#ifdef CONFIG_RCU_FANOUT_LEAF
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#define RCU_FANOUT_LEAF CONFIG_RCU_FANOUT_LEAF
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#else /* #ifdef CONFIG_RCU_FANOUT_LEAF */
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# ifdef CONFIG_64BIT
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# define RCU_FANOUT_LEAF 64
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# else
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# define RCU_FANOUT_LEAF 32
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# endif
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#endif /* #else #ifdef CONFIG_RCU_FANOUT_LEAF */
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#define RCU_FANOUT_1 (RCU_FANOUT_LEAF)
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#define RCU_FANOUT_2 (RCU_FANOUT_1 * RCU_FANOUT)
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#define RCU_FANOUT_3 (RCU_FANOUT_2 * RCU_FANOUT)
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#define RCU_FANOUT_4 (RCU_FANOUT_3 * RCU_FANOUT)
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#if NR_CPUS <= RCU_FANOUT_1
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# define RCU_NUM_LVLS 1
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# define NUM_RCU_LVL_0 1
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# define NUM_RCU_NODES NUM_RCU_LVL_0
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# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0 }
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# define RCU_NODE_NAME_INIT { "rcu_node_0" }
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# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0" }
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#elif NR_CPUS <= RCU_FANOUT_2
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# define RCU_NUM_LVLS 2
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# define NUM_RCU_LVL_0 1
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# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
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# define NUM_RCU_NODES (NUM_RCU_LVL_0 + NUM_RCU_LVL_1)
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# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1 }
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# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1" }
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# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1" }
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#elif NR_CPUS <= RCU_FANOUT_3
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# define RCU_NUM_LVLS 3
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# define NUM_RCU_LVL_0 1
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# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
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# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
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# define NUM_RCU_NODES (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2)
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# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1, NUM_RCU_LVL_2 }
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# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1", "rcu_node_2" }
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# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2" }
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#elif NR_CPUS <= RCU_FANOUT_4
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# define RCU_NUM_LVLS 4
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# define NUM_RCU_LVL_0 1
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# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
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# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
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# define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
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# define NUM_RCU_NODES (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3)
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# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1, NUM_RCU_LVL_2, NUM_RCU_LVL_3 }
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# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1", "rcu_node_2", "rcu_node_3" }
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# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2", "rcu_node_fqs_3" }
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#else
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# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
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#endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
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extern int rcu_num_lvls;
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extern int rcu_num_nodes;
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/*
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* Dynticks per-CPU state.
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*/
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struct rcu_dynticks {
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long long dynticks_nesting; /* Track irq/process nesting level. */
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/* Process level is worth LLONG_MAX/2. */
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int dynticks_nmi_nesting; /* Track NMI nesting level. */
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atomic_t dynticks; /* Even value for idle, else odd. */
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#ifdef CONFIG_NO_HZ_FULL_SYSIDLE
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long long dynticks_idle_nesting;
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/* irq/process nesting level from idle. */
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atomic_t dynticks_idle; /* Even value for idle, else odd. */
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/* "Idle" excludes userspace execution. */
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unsigned long dynticks_idle_jiffies;
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/* End of last non-NMI non-idle period. */
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#endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
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#ifdef CONFIG_RCU_FAST_NO_HZ
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bool all_lazy; /* Are all CPU's CBs lazy? */
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unsigned long nonlazy_posted;
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/* # times non-lazy CBs posted to CPU. */
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unsigned long nonlazy_posted_snap;
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/* idle-period nonlazy_posted snapshot. */
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unsigned long last_accelerate;
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/* Last jiffy CBs were accelerated. */
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unsigned long last_advance_all;
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/* Last jiffy CBs were all advanced. */
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int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
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#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
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};
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/* RCU's kthread states for tracing. */
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#define RCU_KTHREAD_STOPPED 0
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#define RCU_KTHREAD_RUNNING 1
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#define RCU_KTHREAD_WAITING 2
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#define RCU_KTHREAD_OFFCPU 3
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#define RCU_KTHREAD_YIELDING 4
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#define RCU_KTHREAD_MAX 4
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/*
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* Definition for node within the RCU grace-period-detection hierarchy.
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*/
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struct rcu_node {
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raw_spinlock_t __private lock; /* Root rcu_node's lock protects */
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/* some rcu_state fields as well as */
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/* following. */
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unsigned long gpnum; /* Current grace period for this node. */
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/* This will either be equal to or one */
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/* behind the root rcu_node's gpnum. */
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unsigned long completed; /* Last GP completed for this node. */
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/* This will either be equal to or one */
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/* behind the root rcu_node's gpnum. */
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unsigned long qsmask; /* CPUs or groups that need to switch in */
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/* order for current grace period to proceed.*/
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/* In leaf rcu_node, each bit corresponds to */
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/* an rcu_data structure, otherwise, each */
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/* bit corresponds to a child rcu_node */
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/* structure. */
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unsigned long qsmaskinit;
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/* Per-GP initial value for qsmask. */
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/* Initialized from ->qsmaskinitnext at the */
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/* beginning of each grace period. */
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unsigned long qsmaskinitnext;
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/* Online CPUs for next grace period. */
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unsigned long expmask; /* CPUs or groups that need to check in */
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/* to allow the current expedited GP */
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/* to complete. */
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unsigned long expmaskinit;
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/* Per-GP initial values for expmask. */
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/* Initialized from ->expmaskinitnext at the */
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/* beginning of each expedited GP. */
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unsigned long expmaskinitnext;
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/* Online CPUs for next expedited GP. */
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/* Any CPU that has ever been online will */
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/* have its bit set. */
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unsigned long grpmask; /* Mask to apply to parent qsmask. */
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/* Only one bit will be set in this mask. */
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int grplo; /* lowest-numbered CPU or group here. */
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int grphi; /* highest-numbered CPU or group here. */
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u8 grpnum; /* CPU/group number for next level up. */
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u8 level; /* root is at level 0. */
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bool wait_blkd_tasks;/* Necessary to wait for blocked tasks to */
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/* exit RCU read-side critical sections */
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/* before propagating offline up the */
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/* rcu_node tree? */
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struct rcu_node *parent;
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struct list_head blkd_tasks;
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/* Tasks blocked in RCU read-side critical */
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/* section. Tasks are placed at the head */
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/* of this list and age towards the tail. */
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struct list_head *gp_tasks;
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/* Pointer to the first task blocking the */
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/* current grace period, or NULL if there */
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/* is no such task. */
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struct list_head *exp_tasks;
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/* Pointer to the first task blocking the */
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/* current expedited grace period, or NULL */
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/* if there is no such task. If there */
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/* is no current expedited grace period, */
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/* then there can cannot be any such task. */
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struct list_head *boost_tasks;
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/* Pointer to first task that needs to be */
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/* priority boosted, or NULL if no priority */
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/* boosting is needed for this rcu_node */
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/* structure. If there are no tasks */
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/* queued on this rcu_node structure that */
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/* are blocking the current grace period, */
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/* there can be no such task. */
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struct rt_mutex boost_mtx;
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/* Used only for the priority-boosting */
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/* side effect, not as a lock. */
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unsigned long boost_time;
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/* When to start boosting (jiffies). */
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struct task_struct *boost_kthread_task;
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/* kthread that takes care of priority */
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/* boosting for this rcu_node structure. */
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unsigned int boost_kthread_status;
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/* State of boost_kthread_task for tracing. */
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unsigned long n_tasks_boosted;
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/* Total number of tasks boosted. */
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unsigned long n_exp_boosts;
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/* Number of tasks boosted for expedited GP. */
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unsigned long n_normal_boosts;
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/* Number of tasks boosted for normal GP. */
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unsigned long n_balk_blkd_tasks;
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/* Refused to boost: no blocked tasks. */
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unsigned long n_balk_exp_gp_tasks;
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/* Refused to boost: nothing blocking GP. */
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unsigned long n_balk_boost_tasks;
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/* Refused to boost: already boosting. */
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unsigned long n_balk_notblocked;
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/* Refused to boost: RCU RS CS still running. */
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unsigned long n_balk_notyet;
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/* Refused to boost: not yet time. */
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unsigned long n_balk_nos;
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/* Refused to boost: not sure why, though. */
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/* This can happen due to race conditions. */
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#ifdef CONFIG_RCU_NOCB_CPU
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struct swait_queue_head nocb_gp_wq[2];
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/* Place for rcu_nocb_kthread() to wait GP. */
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#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
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int need_future_gp[2];
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/* Counts of upcoming no-CB GP requests. */
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raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;
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spinlock_t exp_lock ____cacheline_internodealigned_in_smp;
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unsigned long exp_seq_rq;
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wait_queue_head_t exp_wq[4];
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} ____cacheline_internodealigned_in_smp;
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/*
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* Do a full breadth-first scan of the rcu_node structures for the
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* specified rcu_state structure.
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*/
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#define rcu_for_each_node_breadth_first(rsp, rnp) \
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for ((rnp) = &(rsp)->node[0]; \
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(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
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/*
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* Do a breadth-first scan of the non-leaf rcu_node structures for the
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* specified rcu_state structure. Note that if there is a singleton
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* rcu_node tree with but one rcu_node structure, this loop is a no-op.
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*/
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#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
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for ((rnp) = &(rsp)->node[0]; \
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(rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
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/*
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* Scan the leaves of the rcu_node hierarchy for the specified rcu_state
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* structure. Note that if there is a singleton rcu_node tree with but
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* one rcu_node structure, this loop -will- visit the rcu_node structure.
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* It is still a leaf node, even if it is also the root node.
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*/
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#define rcu_for_each_leaf_node(rsp, rnp) \
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for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
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(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
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/*
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* Union to allow "aggregate OR" operation on the need for a quiescent
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* state by the normal and expedited grace periods.
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*/
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union rcu_noqs {
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struct {
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u8 norm;
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u8 exp;
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} b; /* Bits. */
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u16 s; /* Set of bits, aggregate OR here. */
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};
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/* Index values for nxttail array in struct rcu_data. */
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#define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */
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#define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */
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#define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */
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#define RCU_NEXT_TAIL 3
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#define RCU_NEXT_SIZE 4
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/* Per-CPU data for read-copy update. */
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struct rcu_data {
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/* 1) quiescent-state and grace-period handling : */
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unsigned long completed; /* Track rsp->completed gp number */
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/* in order to detect GP end. */
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unsigned long gpnum; /* Highest gp number that this CPU */
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/* is aware of having started. */
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unsigned long rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */
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/* for rcu_all_qs() invocations. */
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union rcu_noqs cpu_no_qs; /* No QSes yet for this CPU. */
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bool core_needs_qs; /* Core waits for quiesc state. */
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bool beenonline; /* CPU online at least once. */
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bool gpwrap; /* Possible gpnum/completed wrap. */
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struct rcu_node *mynode; /* This CPU's leaf of hierarchy */
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unsigned long grpmask; /* Mask to apply to leaf qsmask. */
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unsigned long ticks_this_gp; /* The number of scheduling-clock */
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/* ticks this CPU has handled */
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/* during and after the last grace */
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/* period it is aware of. */
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/* 2) batch handling */
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/*
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* If nxtlist is not NULL, it is partitioned as follows.
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* Any of the partitions might be empty, in which case the
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* pointer to that partition will be equal to the pointer for
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* the following partition. When the list is empty, all of
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* the nxttail elements point to the ->nxtlist pointer itself,
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* which in that case is NULL.
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*
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* [nxtlist, *nxttail[RCU_DONE_TAIL]):
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* Entries that batch # <= ->completed
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* The grace period for these entries has completed, and
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* the other grace-period-completed entries may be moved
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* here temporarily in rcu_process_callbacks().
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* [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]):
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* Entries that batch # <= ->completed - 1: waiting for current GP
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* [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]):
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* Entries known to have arrived before current GP ended
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* [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]):
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* Entries that might have arrived after current GP ended
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* Note that the value of *nxttail[RCU_NEXT_TAIL] will
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* always be NULL, as this is the end of the list.
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*/
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struct rcu_head *nxtlist;
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struct rcu_head **nxttail[RCU_NEXT_SIZE];
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unsigned long nxtcompleted[RCU_NEXT_SIZE];
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/* grace periods for sublists. */
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long qlen_lazy; /* # of lazy queued callbacks */
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long qlen; /* # of queued callbacks, incl lazy */
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long qlen_last_fqs_check;
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/* qlen at last check for QS forcing */
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unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */
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unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */
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unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */
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unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */
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unsigned long n_force_qs_snap;
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/* did other CPU force QS recently? */
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long blimit; /* Upper limit on a processed batch */
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/* 3) dynticks interface. */
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struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */
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int dynticks_snap; /* Per-GP tracking for dynticks. */
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/* 4) reasons this CPU needed to be kicked by force_quiescent_state */
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unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
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unsigned long offline_fqs; /* Kicked due to being offline. */
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unsigned long cond_resched_completed;
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/* Grace period that needs help */
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/* from cond_resched(). */
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/* 5) __rcu_pending() statistics. */
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unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */
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unsigned long n_rp_core_needs_qs;
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unsigned long n_rp_report_qs;
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unsigned long n_rp_cb_ready;
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unsigned long n_rp_cpu_needs_gp;
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unsigned long n_rp_gp_completed;
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unsigned long n_rp_gp_started;
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unsigned long n_rp_nocb_defer_wakeup;
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unsigned long n_rp_need_nothing;
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/* 6) _rcu_barrier(), OOM callbacks, and expediting. */
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struct rcu_head barrier_head;
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#ifdef CONFIG_RCU_FAST_NO_HZ
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struct rcu_head oom_head;
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#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
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atomic_long_t exp_workdone1; /* # done by others #1. */
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atomic_long_t exp_workdone2; /* # done by others #2. */
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atomic_long_t exp_workdone3; /* # done by others #3. */
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/* 7) Callback offloading. */
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#ifdef CONFIG_RCU_NOCB_CPU
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struct rcu_head *nocb_head; /* CBs waiting for kthread. */
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struct rcu_head **nocb_tail;
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atomic_long_t nocb_q_count; /* # CBs waiting for nocb */
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atomic_long_t nocb_q_count_lazy; /* invocation (all stages). */
|
|
struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */
|
|
struct rcu_head **nocb_follower_tail;
|
|
struct swait_queue_head nocb_wq; /* For nocb kthreads to sleep on. */
|
|
struct task_struct *nocb_kthread;
|
|
int nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */
|
|
|
|
/* The following fields are used by the leader, hence own cacheline. */
|
|
struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp;
|
|
/* CBs waiting for GP. */
|
|
struct rcu_head **nocb_gp_tail;
|
|
bool nocb_leader_sleep; /* Is the nocb leader thread asleep? */
|
|
struct rcu_data *nocb_next_follower;
|
|
/* Next follower in wakeup chain. */
|
|
|
|
/* The following fields are used by the follower, hence new cachline. */
|
|
struct rcu_data *nocb_leader ____cacheline_internodealigned_in_smp;
|
|
/* Leader CPU takes GP-end wakeups. */
|
|
#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
|
|
|
|
/* 8) RCU CPU stall data. */
|
|
unsigned int softirq_snap; /* Snapshot of softirq activity. */
|
|
|
|
int cpu;
|
|
struct rcu_state *rsp;
|
|
};
|
|
|
|
/* Values for nocb_defer_wakeup field in struct rcu_data. */
|
|
#define RCU_NOGP_WAKE_NOT 0
|
|
#define RCU_NOGP_WAKE 1
|
|
#define RCU_NOGP_WAKE_FORCE 2
|
|
|
|
#define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500))
|
|
/* For jiffies_till_first_fqs and */
|
|
/* and jiffies_till_next_fqs. */
|
|
|
|
#define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */
|
|
/* delay between bouts of */
|
|
/* quiescent-state forcing. */
|
|
|
|
#define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */
|
|
/* at least one scheduling clock */
|
|
/* irq before ratting on them. */
|
|
|
|
#define rcu_wait(cond) \
|
|
do { \
|
|
for (;;) { \
|
|
set_current_state(TASK_INTERRUPTIBLE); \
|
|
if (cond) \
|
|
break; \
|
|
schedule(); \
|
|
} \
|
|
__set_current_state(TASK_RUNNING); \
|
|
} while (0)
|
|
|
|
/*
|
|
* 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[RCU_NUM_LVLS + 1];
|
|
/* Hierarchy levels (+1 to */
|
|
/* shut bogus gcc warning) */
|
|
u8 flavor_mask; /* bit in flavor mask. */
|
|
struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
|
|
call_rcu_func_t call; /* call_rcu() flavor. */
|
|
int ncpus; /* # CPUs seen so far. */
|
|
|
|
/* The following fields are guarded by the root rcu_node's lock. */
|
|
|
|
u8 boost ____cacheline_internodealigned_in_smp;
|
|
/* Subject to priority boost. */
|
|
unsigned long gpnum; /* Current gp number. */
|
|
unsigned long completed; /* # of last completed gp. */
|
|
struct task_struct *gp_kthread; /* Task for grace periods. */
|
|
struct swait_queue_head gp_wq; /* Where GP task waits. */
|
|
short gp_flags; /* Commands for GP task. */
|
|
short gp_state; /* GP kthread sleep state. */
|
|
|
|
/* End of fields guarded by root rcu_node's lock. */
|
|
|
|
raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp;
|
|
/* Protect following fields. */
|
|
struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */
|
|
/* need a grace period. */
|
|
struct rcu_head **orphan_nxttail; /* Tail of above. */
|
|
struct rcu_head *orphan_donelist; /* Orphaned callbacks that */
|
|
/* are ready to invoke. */
|
|
struct rcu_head **orphan_donetail; /* Tail of above. */
|
|
long qlen_lazy; /* Number of lazy callbacks. */
|
|
long qlen; /* Total number of callbacks. */
|
|
/* End of fields guarded by orphan_lock. */
|
|
|
|
struct mutex barrier_mutex; /* Guards barrier fields. */
|
|
atomic_t barrier_cpu_count; /* # CPUs waiting on. */
|
|
struct completion barrier_completion; /* Wake at barrier end. */
|
|
unsigned long barrier_sequence; /* ++ at start and end of */
|
|
/* _rcu_barrier(). */
|
|
/* End of fields guarded by barrier_mutex. */
|
|
|
|
struct mutex exp_mutex; /* Serialize expedited GP. */
|
|
struct mutex exp_wake_mutex; /* Serialize wakeup. */
|
|
unsigned long expedited_sequence; /* Take a ticket. */
|
|
atomic_long_t expedited_normal; /* # fallbacks to normal. */
|
|
atomic_t expedited_need_qs; /* # CPUs left to check in. */
|
|
struct swait_queue_head expedited_wq; /* Wait for check-ins. */
|
|
int ncpus_snap; /* # CPUs seen last time. */
|
|
|
|
unsigned long jiffies_force_qs; /* Time at which to invoke */
|
|
/* force_quiescent_state(). */
|
|
unsigned long jiffies_kick_kthreads; /* Time at which to kick */
|
|
/* kthreads, if configured. */
|
|
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. */
|
|
unsigned long gp_start; /* Time at which GP started, */
|
|
/* but in jiffies. */
|
|
unsigned long gp_activity; /* Time of last GP kthread */
|
|
/* activity in jiffies. */
|
|
unsigned long jiffies_stall; /* Time at which to check */
|
|
/* for CPU stalls. */
|
|
unsigned long jiffies_resched; /* Time at which to resched */
|
|
/* a reluctant CPU. */
|
|
unsigned long n_force_qs_gpstart; /* Snapshot of n_force_qs at */
|
|
/* GP start. */
|
|
unsigned long gp_max; /* Maximum GP duration in */
|
|
/* jiffies. */
|
|
const char *name; /* Name of structure. */
|
|
char abbr; /* Abbreviated name. */
|
|
struct list_head flavors; /* List of RCU flavors. */
|
|
};
|
|
|
|
/* Values for rcu_state structure's gp_flags field. */
|
|
#define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */
|
|
#define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
|
|
|
|
/* Values for rcu_state structure's gp_state field. */
|
|
#define RCU_GP_IDLE 0 /* Initial state and no GP in progress. */
|
|
#define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */
|
|
#define RCU_GP_DONE_GPS 2 /* Wait done for grace-period start. */
|
|
#define RCU_GP_WAIT_FQS 3 /* Wait for force-quiescent-state time. */
|
|
#define RCU_GP_DOING_FQS 4 /* Wait done for force-quiescent-state time. */
|
|
#define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */
|
|
#define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */
|
|
|
|
#ifndef RCU_TREE_NONCORE
|
|
static const char * const gp_state_names[] = {
|
|
"RCU_GP_IDLE",
|
|
"RCU_GP_WAIT_GPS",
|
|
"RCU_GP_DONE_GPS",
|
|
"RCU_GP_WAIT_FQS",
|
|
"RCU_GP_DOING_FQS",
|
|
"RCU_GP_CLEANUP",
|
|
"RCU_GP_CLEANED",
|
|
};
|
|
#endif /* #ifndef RCU_TREE_NONCORE */
|
|
|
|
extern struct list_head rcu_struct_flavors;
|
|
|
|
/* Sequence through rcu_state structures for each RCU flavor. */
|
|
#define for_each_rcu_flavor(rsp) \
|
|
list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
|
|
|
|
/*
|
|
* RCU implementation internal declarations:
|
|
*/
|
|
extern struct rcu_state rcu_sched_state;
|
|
|
|
extern struct rcu_state rcu_bh_state;
|
|
|
|
#ifdef CONFIG_PREEMPT_RCU
|
|
extern struct rcu_state rcu_preempt_state;
|
|
#endif /* #ifdef CONFIG_PREEMPT_RCU */
|
|
|
|
#ifdef CONFIG_RCU_BOOST
|
|
DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
|
|
DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
|
|
DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
|
|
DECLARE_PER_CPU(char, rcu_cpu_has_work);
|
|
#endif /* #ifdef CONFIG_RCU_BOOST */
|
|
|
|
#ifndef RCU_TREE_NONCORE
|
|
|
|
/* Forward declarations for rcutree_plugin.h */
|
|
static void rcu_bootup_announce(void);
|
|
static void rcu_preempt_note_context_switch(void);
|
|
static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
|
|
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
|
|
static void rcu_print_detail_task_stall(struct rcu_state *rsp);
|
|
static int rcu_print_task_stall(struct rcu_node *rnp);
|
|
static int rcu_print_task_exp_stall(struct rcu_node *rnp);
|
|
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
|
|
static void rcu_preempt_check_callbacks(void);
|
|
void call_rcu(struct rcu_head *head, rcu_callback_t func);
|
|
static void __init __rcu_init_preempt(void);
|
|
static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
|
|
static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
|
|
static void invoke_rcu_callbacks_kthread(void);
|
|
static bool rcu_is_callbacks_kthread(void);
|
|
#ifdef CONFIG_RCU_BOOST
|
|
static void rcu_preempt_do_callbacks(void);
|
|
static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
|
|
struct rcu_node *rnp);
|
|
#endif /* #ifdef CONFIG_RCU_BOOST */
|
|
static void __init rcu_spawn_boost_kthreads(void);
|
|
static void rcu_prepare_kthreads(int cpu);
|
|
static void rcu_cleanup_after_idle(void);
|
|
static void rcu_prepare_for_idle(void);
|
|
static void rcu_idle_count_callbacks_posted(void);
|
|
static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
|
|
static void print_cpu_stall_info_begin(void);
|
|
static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
|
|
static void print_cpu_stall_info_end(void);
|
|
static void zero_cpu_stall_ticks(struct rcu_data *rdp);
|
|
static void increment_cpu_stall_ticks(void);
|
|
static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu);
|
|
static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq);
|
|
static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp);
|
|
static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq);
|
|
static void rcu_init_one_nocb(struct rcu_node *rnp);
|
|
static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
|
|
bool lazy, unsigned long flags);
|
|
static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
|
|
struct rcu_data *rdp,
|
|
unsigned long flags);
|
|
static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp);
|
|
static void do_nocb_deferred_wakeup(struct rcu_data *rdp);
|
|
static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
|
|
static void rcu_spawn_all_nocb_kthreads(int cpu);
|
|
static void __init rcu_spawn_nocb_kthreads(void);
|
|
#ifdef CONFIG_RCU_NOCB_CPU
|
|
static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp);
|
|
#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
|
|
static void __maybe_unused rcu_kick_nohz_cpu(int cpu);
|
|
static bool init_nocb_callback_list(struct rcu_data *rdp);
|
|
static void rcu_sysidle_enter(int irq);
|
|
static void rcu_sysidle_exit(int irq);
|
|
static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
|
|
unsigned long *maxj);
|
|
static bool is_sysidle_rcu_state(struct rcu_state *rsp);
|
|
static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle,
|
|
unsigned long maxj);
|
|
static void rcu_bind_gp_kthread(void);
|
|
static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp);
|
|
static bool rcu_nohz_full_cpu(struct rcu_state *rsp);
|
|
static void rcu_dynticks_task_enter(void);
|
|
static void rcu_dynticks_task_exit(void);
|
|
|
|
#endif /* #ifndef RCU_TREE_NONCORE */
|
|
|
|
#ifdef CONFIG_RCU_TRACE
|
|
/* Read out queue lengths for tracing. */
|
|
static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
|
|
{
|
|
#ifdef CONFIG_RCU_NOCB_CPU
|
|
*ql = atomic_long_read(&rdp->nocb_q_count);
|
|
*qll = atomic_long_read(&rdp->nocb_q_count_lazy);
|
|
#else /* #ifdef CONFIG_RCU_NOCB_CPU */
|
|
*ql = 0;
|
|
*qll = 0;
|
|
#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
|
|
}
|
|
#endif /* #ifdef CONFIG_RCU_TRACE */
|
|
|
|
/*
|
|
* Place this after a lock-acquisition primitive to guarantee that
|
|
* an UNLOCK+LOCK pair act as a full barrier. This guarantee applies
|
|
* if the UNLOCK and LOCK are executed by the same CPU or if the
|
|
* UNLOCK and LOCK operate on the same lock variable.
|
|
*/
|
|
#ifdef CONFIG_PPC
|
|
#define smp_mb__after_unlock_lock() smp_mb() /* Full ordering for lock. */
|
|
#else /* #ifdef CONFIG_PPC */
|
|
#define smp_mb__after_unlock_lock() do { } while (0)
|
|
#endif /* #else #ifdef CONFIG_PPC */
|
|
|
|
/*
|
|
* Wrappers for the rcu_node::lock acquire and release.
|
|
*
|
|
* Because the rcu_nodes form a tree, the tree traversal locking will observe
|
|
* different lock values, this in turn means that an UNLOCK of one level
|
|
* followed by a LOCK of another level does not imply a full memory barrier;
|
|
* and most importantly transitivity is lost.
|
|
*
|
|
* In order to restore full ordering between tree levels, augment the regular
|
|
* lock acquire functions with smp_mb__after_unlock_lock().
|
|
*
|
|
* As ->lock of struct rcu_node is a __private field, therefore one should use
|
|
* these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
|
|
*/
|
|
static inline void raw_spin_lock_rcu_node(struct rcu_node *rnp)
|
|
{
|
|
raw_spin_lock(&ACCESS_PRIVATE(rnp, lock));
|
|
smp_mb__after_unlock_lock();
|
|
}
|
|
|
|
static inline void raw_spin_unlock_rcu_node(struct rcu_node *rnp)
|
|
{
|
|
raw_spin_unlock(&ACCESS_PRIVATE(rnp, lock));
|
|
}
|
|
|
|
static inline void raw_spin_lock_irq_rcu_node(struct rcu_node *rnp)
|
|
{
|
|
raw_spin_lock_irq(&ACCESS_PRIVATE(rnp, lock));
|
|
smp_mb__after_unlock_lock();
|
|
}
|
|
|
|
static inline void raw_spin_unlock_irq_rcu_node(struct rcu_node *rnp)
|
|
{
|
|
raw_spin_unlock_irq(&ACCESS_PRIVATE(rnp, lock));
|
|
}
|
|
|
|
#define raw_spin_lock_irqsave_rcu_node(rnp, flags) \
|
|
do { \
|
|
typecheck(unsigned long, flags); \
|
|
raw_spin_lock_irqsave(&ACCESS_PRIVATE(rnp, lock), flags); \
|
|
smp_mb__after_unlock_lock(); \
|
|
} while (0)
|
|
|
|
#define raw_spin_unlock_irqrestore_rcu_node(rnp, flags) \
|
|
do { \
|
|
typecheck(unsigned long, flags); \
|
|
raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(rnp, lock), flags); \
|
|
} while (0)
|
|
|
|
static inline bool raw_spin_trylock_rcu_node(struct rcu_node *rnp)
|
|
{
|
|
bool locked = raw_spin_trylock(&ACCESS_PRIVATE(rnp, lock));
|
|
|
|
if (locked)
|
|
smp_mb__after_unlock_lock();
|
|
return locked;
|
|
}
|