v4.19.13 snapshot.
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
new file mode 100644
index 0000000..4e74df7
--- /dev/null
+++ b/kernel/rcu/tree.h
@@ -0,0 +1,500 @@
+/*
+ * 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 dynticks_nesting; /* Track process nesting level. */
+ long dynticks_nmi_nesting; /* Track irq/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 */
+};
+
+/* Communicate arguments to a workqueue handler. */
+struct rcu_exp_work {
+ smp_call_func_t rew_func;
+ struct rcu_state *rew_rsp;
+ unsigned long rew_s;
+ struct work_struct rew_work;
+};
+
+/* 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 gp_seq; /* Track rsp->rcu_gp_seq. */
+ unsigned long gp_seq_needed; /* Track rsp->rcu_gp_seq_needed. */
+ unsigned long completedqs; /* All QSes done for this node. */
+ 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 rcu_gp_init_mask; /* Mask of offline CPUs at GP init. */
+ 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 ffmask; /* Fully functional CPUs. */
+ 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. */
+#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 */
+ 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];
+ struct rcu_exp_work rew;
+ bool exp_need_flush; /* Need to flush workitem? */
+} ____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. */
+};
+
+/* Per-CPU data for read-copy update. */
+struct rcu_data {
+ /* 1) quiescent-state and grace-period handling : */
+ unsigned long gp_seq; /* Track rsp->rcu_gp_seq counter. */
+ unsigned long gp_seq_needed; /* Track rsp->rcu_gp_seq_needed ctr. */
+ 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 ->gp_seq 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_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 cond_resched_completed;
+ /* Grace period that needs help */
+ /* from cond_resched(). */
+
+ /* 5) _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 */
+ int exp_dynticks_snap; /* Double-check need for IPI. */
+
+ /* 6) 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;
+ raw_spinlock_t nocb_lock; /* Guard following pair of fields. */
+ int nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */
+ struct timer_list nocb_timer; /* Enforce finite deferral. */
+
+ /* 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 */
+
+ /* 7) Diagnostic data, including RCU CPU stall warnings. */
+ unsigned int softirq_snap; /* Snapshot of softirq activity. */
+ /* ->rcu_iw* fields protected by leaf rcu_node ->lock. */
+ struct irq_work rcu_iw; /* Check for non-irq activity. */
+ bool rcu_iw_pending; /* Is ->rcu_iw pending? */
+ unsigned long rcu_iw_gp_seq; /* ->gp_seq associated with ->rcu_iw. */
+ unsigned long rcu_ofl_gp_seq; /* ->gp_seq at last offline. */
+ short rcu_ofl_gp_flags; /* ->gp_flags at last offline. */
+ unsigned long rcu_onl_gp_seq; /* ->gp_seq at last online. */
+ short rcu_onl_gp_flags; /* ->gp_flags at last online. */
+
+ 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 gp_seq; /* Grace-period sequence #. */
+ 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. */
+
+ 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 gp_start; /* Time at which GP started, */
+ /* but in jiffies. */
+ unsigned long gp_activity; /* Time of last GP kthread */
+ /* activity in jiffies. */
+ unsigned long gp_req_activity; /* Time of last GP request */
+ /* 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. */
+
+ spinlock_t ofl_lock ____cacheline_internodealigned_in_smp;
+ /* Synchronize offline with */
+ /* GP pre-initialization. */
+};
+
+/* 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_ONOFF 3 /* Grace-period initialization hotplug. */
+#define RCU_GP_INIT 4 /* Grace-period initialization. */
+#define RCU_GP_WAIT_FQS 5 /* Wait for force-quiescent-state time. */
+#define RCU_GP_DOING_FQS 6 /* Wait done for force-quiescent-state time. */
+#define RCU_GP_CLEANUP 7 /* Grace-period cleanup started. */
+#define RCU_GP_CLEANED 8 /* 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_ONOFF",
+ "RCU_GP_INIT",
+ "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);
+
+#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_state *rsp,
+ 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 dump_blkd_tasks(struct rcu_state *rsp, struct rcu_node *rnp,
+ int ncheck);
+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 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 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_data *my_rdp,
+ 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 bool init_nocb_callback_list(struct rcu_data *rdp);
+static void rcu_bind_gp_kthread(void);
+static bool rcu_nohz_full_cpu(struct rcu_state *rsp);
+static void rcu_dynticks_task_enter(void);
+static void rcu_dynticks_task_exit(void);
+
+#ifdef CONFIG_SRCU
+void srcu_online_cpu(unsigned int cpu);
+void srcu_offline_cpu(unsigned int cpu);
+#else /* #ifdef CONFIG_SRCU */
+void srcu_online_cpu(unsigned int cpu) { }
+void srcu_offline_cpu(unsigned int cpu) { }
+#endif /* #else #ifdef CONFIG_SRCU */
+
+#endif /* #ifndef RCU_TREE_NONCORE */