/* * 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, you can access it online at * http://www.gnu.org/licenses/gpl-2.0.html. * * 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/rtmutex.h>#include <linux/threads.h>#include <linux/cpumask.h>#include <linux/seqlock.h>#include <linux/swait.h>#include <linux/stop_machine.h>#include <linux/rcu_node_tree.h> #include "rcu_segcblist.h" /* * Dynticks per-CPU state. */struct rcu_dynticks { long long dynticks_nesting; /* Track irq/process nesting level. */ /* Process level is worth LLONG_MAX/2. */ int dynticks_nmi_nesting; /* Track NMI nesting level. */ atomic_t dynticks; /* Even value for idle, else odd. */ bool rcu_need_heavy_qs; /* GP old, need heavy quiescent state. */ unsigned long rcu_qs_ctr; /* Light universal quiescent state ctr. */ bool rcu_urgent_qs; /* GP old need light quiescent state. */#ifdef CONFIG_RCU_FAST_NO_HZ bool all_lazy; /* Are all CPU's CBs lazy? */ unsigned long nonlazy_posted; /* # times non-lazy CBs posted to CPU. */ unsigned long nonlazy_posted_snap; /* idle-period nonlazy_posted snapshot. */ unsigned long last_accelerate; /* Last jiffy CBs were accelerated. */ unsigned long last_advance_all; /* Last jiffy CBs were all advanced. */ int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */}; /* RCU's kthread states for tracing. */#define RCU_KTHREAD_STOPPED 0#define RCU_KTHREAD_RUNNING 1#define RCU_KTHREAD_WAITING 2#define RCU_KTHREAD_OFFCPU 3#define RCU_KTHREAD_YIELDING 4#define RCU_KTHREAD_MAX 4 /* * Definition for node within the RCU grace-period-detection hierarchy. */struct rcu_node { raw_spinlock_t __private lock; /* Root rcu_node's lock protects */ /* some rcu_state fields as well as */ /* following. */ unsigned 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 completed; /* Last GP completed 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.*/ /* In leaf rcu_node, each bit corresponds to */ /* an rcu_data structure, otherwise, each */ /* bit corresponds to a child rcu_node */ /* structure. */ unsigned long qsmaskinit; /* Per-GP initial value for qsmask. */ /* Initialized from ->qsmaskinitnext at the */ /* beginning of each grace period. */ unsigned long qsmaskinitnext; /* Online CPUs for next grace period. */ unsigned long expmask; /* CPUs or groups that need to check in */ /* to allow the current expedited GP */ /* to complete. */ unsigned long expmaskinit; /* Per-GP initial values for expmask. */ /* Initialized from ->expmaskinitnext at the */ /* beginning of each expedited GP. */ unsigned long expmaskinitnext; /* Online CPUs for next expedited GP. */ /* Any CPU that has ever been online will */ /* have its bit set. */ unsigned long grpmask; /* Mask to apply to parent qsmask. */ /* Only one bit will be set in this mask. */ 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. */ bool wait_blkd_tasks;/* Necessary to wait for blocked tasks to */ /* exit RCU read-side critical sections */ /* before propagating offline up the */ /* rcu_node tree? */ struct rcu_node *parent; struct list_head blkd_tasks; /* Tasks blocked in RCU read-side critical */ /* section. Tasks are placed at the head */ /* of this list and age towards the tail. */ struct list_head *gp_tasks; /* Pointer to the first task blocking the */ /* current grace period, or NULL if there */ /* is no such task. */ struct list_head *exp_tasks; /* Pointer to the first task blocking the */ /* current expedited grace period, or NULL */ /* if there is no such task. If there */ /* is no current expedited grace period, */ /* then there can cannot be any such task. */ struct list_head *boost_tasks; /* Pointer to first task that needs to be */ /* priority boosted, or NULL if no priority */ /* boosting is needed for this rcu_node */ /* structure. If there are no tasks */ /* queued on this rcu_node structure that */ /* are blocking the current grace period, */ /* there can be no such task. */ struct rt_mutex boost_mtx; /* Used only for the priority-boosting */ /* side effect, not as a lock. */ unsigned long boost_time; /* When to start boosting (jiffies). */ struct task_struct *boost_kthread_task; /* kthread that takes care of priority */ /* boosting for this rcu_node structure. */ unsigned int boost_kthread_status; /* State of boost_kthread_task for tracing. */ unsigned long n_tasks_boosted; /* Total number of tasks boosted. */ unsigned long n_exp_boosts; /* Number of tasks boosted for expedited GP. */ unsigned long n_normal_boosts; /* Number of tasks boosted for normal GP. */#ifdef CONFIG_RCU_NOCB_CPU struct swait_queue_head nocb_gp_wq[2]; /* Place for rcu_nocb_kthread() to wait GP. */#endif /* #ifdef CONFIG_RCU_NOCB_CPU */ int need_future_gp[2]; /* Counts of upcoming no-CB GP requests. */ raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp; spinlock_t exp_lock ____cacheline_internodealigned_in_smp; unsigned long exp_seq_rq; wait_queue_head_t exp_wq[4];} ____cacheline_internodealigned_in_smp; /* * Bitmasks in an rcu_node cover the interval [grplo, grphi] of CPU IDs, and * are indexed relative to this interval rather than the global CPU ID space. * This generates the bit for a CPU in node-local masks. */#define leaf_node_cpu_bit(rnp, cpu) (1UL << ((cpu) - (rnp)->grplo)) /* * Union to allow "aggregate OR" operation on the need for a quiescent * state by the normal and expedited grace periods. */union rcu_noqs { struct { u8 norm; u8 exp; } b; /* Bits. */ u16 s; /* Set of bits, aggregate OR here. */}; /* 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 : */ unsigned long completed; /* Track rsp->completed gp number */ /* in order to detect GP end. */ unsigned long gpnum; /* Highest gp number that this CPU */ /* is aware of having started. */ unsigned long rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */ /* for rcu_all_qs() invocations. */ union rcu_noqs cpu_no_qs; /* No QSes yet for this CPU. */ bool core_needs_qs; /* Core waits for quiesc state. */ bool beenonline; /* CPU online at least once. */ bool gpwrap; /* Possible gpnum/completed wrap. */ struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ unsigned long grpmask; /* Mask to apply to leaf qsmask. */ unsigned long ticks_this_gp; /* The number of scheduling-clock */ /* ticks this CPU has handled */ /* during and after the last grace */ /* period it is aware of. */ /* 2) batch handling */ struct rcu_segcblist cblist; /* Segmented callback list, with */ /* different callbacks waiting for */ /* different grace periods. */ long qlen_last_fqs_check; /* qlen at last check for QS forcing */ unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */ unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ unsigned long n_force_qs_snap; /* did other CPU force QS recently? */ long blimit; /* Upper limit on a processed batch */ /* 3) dynticks interface. */ struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ int dynticks_snap; /* Per-GP tracking for dynticks. */ /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ unsigned long offline_fqs; /* Kicked due to being offline. */ unsigned long cond_resched_completed; /* Grace period that needs help */ /* from cond_resched(). */ /* 5) __rcu_pending() statistics. */ unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ unsigned long n_rp_core_needs_qs; unsigned long n_rp_report_qs; unsigned long n_rp_cb_ready; unsigned long n_rp_cpu_needs_gp; unsigned long n_rp_gp_completed; unsigned long n_rp_gp_started; unsigned long n_rp_nocb_defer_wakeup; unsigned long n_rp_need_nothing; /* 6) _rcu_barrier(), OOM callbacks, and expediting. */ struct rcu_head barrier_head;#ifdef CONFIG_RCU_FAST_NO_HZ struct rcu_head oom_head;#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ atomic_long_t exp_workdone0; /* # done by workqueue. */ atomic_long_t exp_workdone1; /* # done by others #1. */ atomic_long_t exp_workdone2; /* # done by others #2. */ atomic_long_t exp_workdone3; /* # done by others #3. */ int exp_dynticks_snap; /* Double-check need for IPI. */ /* 7) Callback offloading. */#ifdef CONFIG_RCU_NOCB_CPU struct rcu_head *nocb_head; /* CBs waiting for kthread. */ struct rcu_head **nocb_tail; atomic_long_t nocb_q_count; /* # CBs waiting for nocb */ 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_NOCB_WAKE_NOT 0#define RCU_NOCB_WAKE 1#define RCU_NOCB_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) */ 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_cblist orphan_pend; /* Orphaned callbacks that */ /* need a grace period. */ struct rcu_cblist orphan_done; /* Orphaned callbacks that */ /* are ready to invoke. */ /* (Contains counts.) */ /* 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_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_NONCOREstatic 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_RCUextern struct rcu_state rcu_preempt_state;#endif /* #ifdef CONFIG_PREEMPT_RCU */ int rcu_dynticks_snap(struct rcu_dynticks *rdtp);bool rcu_eqs_special_set(int cpu); #ifdef CONFIG_RCU_BOOSTDECLARE_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(bool preempt);static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);#ifdef CONFIG_HOTPLUG_CPUstatic 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_BOOSTstatic 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);Lines 1–500 of 524. 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/* * 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, you can access it online at * http://www.gnu.org/licenses/gpl-2.0.html. * * 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/rtmutex.h> #include <linux/threads.h> #include <linux/cpumask.h> #include <linux/seqlock.h> #include <linux/swait.h> #include <linux/stop_machine.h> #include <linux/rcu_node_tree.h> #include "rcu_segcblist.h" /* * Dynticks per-CPU state. */ struct rcu_dynticks { long long dynticks_nesting; /* Track irq/process nesting level. */ /* Process level is worth LLONG_MAX/2. */ int dynticks_nmi_nesting; /* Track NMI nesting level. */ atomic_t dynticks; /* Even value for idle, else odd. */ bool rcu_need_heavy_qs; /* GP old, need heavy quiescent state. */ unsigned long rcu_qs_ctr; /* Light universal quiescent state ctr. */ bool rcu_urgent_qs; /* GP old need light quiescent state. */ #ifdef CONFIG_RCU_FAST_NO_HZ bool all_lazy; /* Are all CPU's CBs lazy? */ unsigned long nonlazy_posted; /* # times non-lazy CBs posted to CPU. */ unsigned long nonlazy_posted_snap; /* idle-period nonlazy_posted snapshot. */ unsigned long last_accelerate; /* Last jiffy CBs were accelerated. */ unsigned long last_advance_all; /* Last jiffy CBs were all advanced. */ int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */ #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ }; /* RCU's kthread states for tracing. */ #define RCU_KTHREAD_STOPPED 0 #define RCU_KTHREAD_RUNNING 1 #define RCU_KTHREAD_WAITING 2 #define RCU_KTHREAD_OFFCPU 3 #define RCU_KTHREAD_YIELDING 4 #define RCU_KTHREAD_MAX 4 /* * Definition for node within the RCU grace-period-detection hierarchy. */ struct rcu_node { raw_spinlock_t __private lock; /* Root rcu_node's lock protects */ /* some rcu_state fields as well as */ /* following. */ unsigned 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 completed; /* Last GP completed 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.*/ /* In leaf rcu_node, each bit corresponds to */ /* an rcu_data structure, otherwise, each */ /* bit corresponds to a child rcu_node */ /* structure. */ unsigned long qsmaskinit; /* Per-GP initial value for qsmask. */ /* Initialized from ->qsmaskinitnext at the */ /* beginning of each grace period. */ unsigned long qsmaskinitnext; /* Online CPUs for next grace period. */ unsigned long expmask; /* CPUs or groups that need to check in */ /* to allow the current expedited GP */ /* to complete. */ unsigned long expmaskinit; /* Per-GP initial values for expmask. */ /* Initialized from ->expmaskinitnext at the */ /* beginning of each expedited GP. */ unsigned long expmaskinitnext; /* Online CPUs for next expedited GP. */ /* Any CPU that has ever been online will */ /* have its bit set. */ unsigned long grpmask; /* Mask to apply to parent qsmask. */ /* Only one bit will be set in this mask. */ 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. */ bool wait_blkd_tasks;/* Necessary to wait for blocked tasks to */ /* exit RCU read-side critical sections */ /* before propagating offline up the */ /* rcu_node tree? */ struct rcu_node *parent; struct list_head blkd_tasks; /* Tasks blocked in RCU read-side critical */ /* section. Tasks are placed at the head */ /* of this list and age towards the tail. */ struct list_head *gp_tasks; /* Pointer to the first task blocking the */ /* current grace period, or NULL if there */ /* is no such task. */ struct list_head *exp_tasks; /* Pointer to the first task blocking the */ /* current expedited grace period, or NULL */ /* if there is no such task. If there */ /* is no current expedited grace period, */ /* then there can cannot be any such task. */ struct list_head *boost_tasks; /* Pointer to first task that needs to be */ /* priority boosted, or NULL if no priority */ /* boosting is needed for this rcu_node */ /* structure. If there are no tasks */ /* queued on this rcu_node structure that */ /* are blocking the current grace period, */ /* there can be no such task. */ struct rt_mutex boost_mtx; /* Used only for the priority-boosting */ /* side effect, not as a lock. */ unsigned long boost_time; /* When to start boosting (jiffies). */ struct task_struct *boost_kthread_task; /* kthread that takes care of priority */ /* boosting for this rcu_node structure. */ unsigned int boost_kthread_status; /* State of boost_kthread_task for tracing. */ unsigned long n_tasks_boosted; /* Total number of tasks boosted. */ unsigned long n_exp_boosts; /* Number of tasks boosted for expedited GP. */ unsigned long n_normal_boosts; /* Number of tasks boosted for normal GP. */ #ifdef CONFIG_RCU_NOCB_CPU struct swait_queue_head nocb_gp_wq[2]; /* Place for rcu_nocb_kthread() to wait GP. */ #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ int need_future_gp[2]; /* Counts of upcoming no-CB GP requests. */ raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp; spinlock_t exp_lock ____cacheline_internodealigned_in_smp; unsigned long exp_seq_rq; wait_queue_head_t exp_wq[4]; } ____cacheline_internodealigned_in_smp; /* * Bitmasks in an rcu_node cover the interval [grplo, grphi] of CPU IDs, and * are indexed relative to this interval rather than the global CPU ID space. * This generates the bit for a CPU in node-local masks. */ #define leaf_node_cpu_bit(rnp, cpu) (1UL << ((cpu) - (rnp)->grplo)) /* * Union to allow "aggregate OR" operation on the need for a quiescent * state by the normal and expedited grace periods. */ union rcu_noqs { struct { u8 norm; u8 exp; } b; /* Bits. */ u16 s; /* Set of bits, aggregate OR here. */ }; /* 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 : */ unsigned long completed; /* Track rsp->completed gp number */ /* in order to detect GP end. */ unsigned long gpnum; /* Highest gp number that this CPU */ /* is aware of having started. */ unsigned long rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */ /* for rcu_all_qs() invocations. */ union rcu_noqs cpu_no_qs; /* No QSes yet for this CPU. */ bool core_needs_qs; /* Core waits for quiesc state. */ bool beenonline; /* CPU online at least once. */ bool gpwrap; /* Possible gpnum/completed wrap. */ struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ unsigned long grpmask; /* Mask to apply to leaf qsmask. */ unsigned long ticks_this_gp; /* The number of scheduling-clock */ /* ticks this CPU has handled */ /* during and after the last grace */ /* period it is aware of. */ /* 2) batch handling */ struct rcu_segcblist cblist; /* Segmented callback list, with */ /* different callbacks waiting for */ /* different grace periods. */ long qlen_last_fqs_check; /* qlen at last check for QS forcing */ unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */ unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ unsigned long n_force_qs_snap; /* did other CPU force QS recently? */ long blimit; /* Upper limit on a processed batch */ /* 3) dynticks interface. */ struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ int dynticks_snap; /* Per-GP tracking for dynticks. */ /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ unsigned long offline_fqs; /* Kicked due to being offline. */ unsigned long cond_resched_completed; /* Grace period that needs help */ /* from cond_resched(). */ /* 5) __rcu_pending() statistics. */ unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ unsigned long n_rp_core_needs_qs; unsigned long n_rp_report_qs; unsigned long n_rp_cb_ready; unsigned long n_rp_cpu_needs_gp; unsigned long n_rp_gp_completed; unsigned long n_rp_gp_started; unsigned long n_rp_nocb_defer_wakeup; unsigned long n_rp_need_nothing; /* 6) _rcu_barrier(), OOM callbacks, and expediting. */ struct rcu_head barrier_head; #ifdef CONFIG_RCU_FAST_NO_HZ struct rcu_head oom_head; #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ atomic_long_t exp_workdone0; /* # done by workqueue. */ atomic_long_t exp_workdone1; /* # done by others #1. */ atomic_long_t exp_workdone2; /* # done by others #2. */ atomic_long_t exp_workdone3; /* # done by others #3. */ int exp_dynticks_snap; /* Double-check need for IPI. */ /* 7) Callback offloading. */ #ifdef CONFIG_RCU_NOCB_CPU struct rcu_head *nocb_head; /* CBs waiting for kthread. */ struct rcu_head **nocb_tail; atomic_long_t nocb_q_count; /* # CBs waiting for nocb */ 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_NOCB_WAKE_NOT 0 #define RCU_NOCB_WAKE 1 #define RCU_NOCB_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) */ 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_cblist orphan_pend; /* Orphaned callbacks that */ /* need a grace period. */ struct rcu_cblist orphan_done; /* Orphaned callbacks that */ /* are ready to invoke. */ /* (Contains counts.) */ /* 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_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 */ int rcu_dynticks_snap(struct rcu_dynticks *rdtp); bool rcu_eqs_special_set(int cpu); #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(bool preempt); 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);