[mirror_ubuntu-jammy-kernel.git] / include / linux / sched.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_SCHED_H
#define _LINUX_SCHED_H

/*
 * Define 'struct task_struct' and provide the main scheduler
 * APIs (schedule(), wakeup variants, etc.)
 */

#include <uapi/linux/sched.h>

#include <asm/current.h>

#include <linux/pid.h>
#include <linux/sem.h>
#include <linux/shm.h>
#include <linux/kcov.h>
#include <linux/mutex.h>
#include <linux/plist.h>
#include <linux/hrtimer.h>
#include <linux/seccomp.h>
#include <linux/nodemask.h>
#include <linux/rcupdate.h>
#include <linux/refcount.h>
#include <linux/resource.h>
#include <linux/latencytop.h>
#include <linux/sched/prio.h>
#include <linux/signal_types.h>
#include <linux/mm_types_task.h>
#include <linux/task_io_accounting.h>
#include <linux/rseq.h>

/* task_struct member predeclarations (sorted alphabetically): */
struct audit_context;
struct backing_dev_info;
struct bio_list;
struct blk_plug;
struct capture_control;
struct cfs_rq;
struct fs_struct;
struct futex_pi_state;
struct io_context;
struct mempolicy;
struct nameidata;
struct nsproxy;
struct perf_event_context;
struct pid_namespace;
struct pipe_inode_info;
struct rcu_node;
struct reclaim_state;
struct robust_list_head;
struct root_domain;
struct rq;
struct sched_attr;
struct sched_param;
struct seq_file;
struct sighand_struct;
struct signal_struct;
struct task_delay_info;
struct task_group;

/*
 * Task state bitmask. NOTE! These bits are also
 * encoded in fs/proc/array.c: get_task_state().
 *
 * We have two separate sets of flags: task->state
 * is about runnability, while task->exit_state are
 * about the task exiting. Confusing, but this way
 * modifying one set can't modify the other one by
 * mistake.
 */

/* Used in tsk->state: */
#define TASK_RUNNING                    0x0000
#define TASK_INTERRUPTIBLE              0x0001
#define TASK_UNINTERRUPTIBLE            0x0002
#define __TASK_STOPPED                  0x0004
#define __TASK_TRACED                   0x0008
/* Used in tsk->exit_state: */
#define EXIT_DEAD                       0x0010
#define EXIT_ZOMBIE                     0x0020
#define EXIT_TRACE                      (EXIT_ZOMBIE | EXIT_DEAD)
/* Used in tsk->state again: */
#define TASK_PARKED                     0x0040
#define TASK_DEAD                       0x0080
#define TASK_WAKEKILL                   0x0100
#define TASK_WAKING                     0x0200
#define TASK_NOLOAD                     0x0400
#define TASK_NEW                        0x0800
#define TASK_STATE_MAX                  0x1000

/* Convenience macros for the sake of set_current_state: */
#define TASK_KILLABLE                   (TASK_WAKEKILL | TASK_UNINTERRUPTIBLE)
#define TASK_STOPPED                    (TASK_WAKEKILL | __TASK_STOPPED)
#define TASK_TRACED                     (TASK_WAKEKILL | __TASK_TRACED)

#define TASK_IDLE                       (TASK_UNINTERRUPTIBLE | TASK_NOLOAD)

/* Convenience macros for the sake of wake_up(): */
#define TASK_NORMAL                     (TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE)

/* get_task_state(): */
#define TASK_REPORT                     (TASK_RUNNING | TASK_INTERRUPTIBLE | \
                                         TASK_UNINTERRUPTIBLE | __TASK_STOPPED | \
                                         __TASK_TRACED | EXIT_DEAD | EXIT_ZOMBIE | \
                                         TASK_PARKED)

#define task_is_traced(task)            ((task->state & __TASK_TRACED) != 0)

#define task_is_stopped(task)           ((task->state & __TASK_STOPPED) != 0)

#define task_is_stopped_or_traced(task) ((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0)

#define task_contributes_to_load(task)  ((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
                                         (task->flags & PF_FROZEN) == 0 && \
                                         (task->state & TASK_NOLOAD) == 0)

#ifdef CONFIG_DEBUG_ATOMIC_SLEEP

/*
 * Special states are those that do not use the normal wait-loop pattern. See
 * the comment with set_special_state().
 */
#define is_special_task_state(state)                            \
        ((state) & (__TASK_STOPPED | __TASK_TRACED | TASK_PARKED | TASK_DEAD))

#define __set_current_state(state_value)                        \
        do {                                                    \
                WARN_ON_ONCE(is_special_task_state(state_value));\
                current->task_state_change = _THIS_IP_;         \
                current->state = (state_value);                 \
        } while (0)

#define set_current_state(state_value)                          \
        do {                                                    \
                WARN_ON_ONCE(is_special_task_state(state_value));\
                current->task_state_change = _THIS_IP_;         \
                smp_store_mb(current->state, (state_value));    \
        } while (0)

#define set_special_state(state_value)                                  \
        do {                                                            \
                unsigned long flags; /* may shadow */                   \
                WARN_ON_ONCE(!is_special_task_state(state_value));      \
                raw_spin_lock_irqsave(&current->pi_lock, flags);        \
                current->task_state_change = _THIS_IP_;                 \
                current->state = (state_value);                         \
                raw_spin_unlock_irqrestore(&current->pi_lock, flags);   \
        } while (0)
#else
/*
 * set_current_state() includes a barrier so that the write of current->state
 * is correctly serialised wrt the caller's subsequent test of whether to
 * actually sleep:
 *
 *   for (;;) {
 *      set_current_state(TASK_UNINTERRUPTIBLE);
 *      if (!need_sleep)
 *              break;
 *
 *      schedule();
 *   }
 *   __set_current_state(TASK_RUNNING);
 *
 * If the caller does not need such serialisation (because, for instance, the
 * condition test and condition change and wakeup are under the same lock) then
 * use __set_current_state().
 *
 * The above is typically ordered against the wakeup, which does:
 *
 *   need_sleep = false;
 *   wake_up_state(p, TASK_UNINTERRUPTIBLE);
 *
 * where wake_up_state() executes a full memory barrier before accessing the
 * task state.
 *
 * Wakeup will do: if (@state & p->state) p->state = TASK_RUNNING, that is,
 * once it observes the TASK_UNINTERRUPTIBLE store the waking CPU can issue a
 * TASK_RUNNING store which can collide with __set_current_state(TASK_RUNNING).
 *
 * However, with slightly different timing the wakeup TASK_RUNNING store can
 * also collide with the TASK_UNINTERRUPTIBLE store. Losing that store is not
 * a problem either because that will result in one extra go around the loop
 * and our @cond test will save the day.
 *
 * Also see the comments of try_to_wake_up().
 */
#define __set_current_state(state_value)                                \
        current->state = (state_value)

#define set_current_state(state_value)                                  \
        smp_store_mb(current->state, (state_value))

/*
 * set_special_state() should be used for those states when the blocking task
 * can not use the regular condition based wait-loop. In that case we must
 * serialize against wakeups such that any possible in-flight TASK_RUNNING stores
 * will not collide with our state change.
 */
#define set_special_state(state_value)                                  \
        do {                                                            \
                unsigned long flags; /* may shadow */                   \
                raw_spin_lock_irqsave(&current->pi_lock, flags);        \
                current->state = (state_value);                         \
                raw_spin_unlock_irqrestore(&current->pi_lock, flags);   \
        } while (0)

#endif

/* Task command name length: */
#define TASK_COMM_LEN                   16

extern void scheduler_tick(void);

#define MAX_SCHEDULE_TIMEOUT            LONG_MAX

extern long schedule_timeout(long timeout);
extern long schedule_timeout_interruptible(long timeout);
extern long schedule_timeout_killable(long timeout);
extern long schedule_timeout_uninterruptible(long timeout);
extern long schedule_timeout_idle(long timeout);
asmlinkage void schedule(void);
extern void schedule_preempt_disabled(void);

extern int __must_check io_schedule_prepare(void);
extern void io_schedule_finish(int token);
extern long io_schedule_timeout(long timeout);
extern void io_schedule(void);

/**
 * struct prev_cputime - snapshot of system and user cputime
 * @utime: time spent in user mode
 * @stime: time spent in system mode
 * @lock: protects the above two fields
 *
 * Stores previous user/system time values such that we can guarantee
 * monotonicity.
 */
struct prev_cputime {
#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
        u64                             utime;
        u64                             stime;
        raw_spinlock_t                  lock;
#endif
};

/**
 * struct task_cputime - collected CPU time counts
 * @utime:              time spent in user mode, in nanoseconds
 * @stime:              time spent in kernel mode, in nanoseconds
 * @sum_exec_runtime:   total time spent on the CPU, in nanoseconds
 *
 * This structure groups together three kinds of CPU time that are tracked for
 * threads and thread groups.  Most things considering CPU time want to group
 * these counts together and treat all three of them in parallel.
 */
struct task_cputime {
        u64                             utime;
        u64                             stime;
        unsigned long long              sum_exec_runtime;
};

/* Alternate field names when used on cache expirations: */
#define virt_exp                        utime
#define prof_exp                        stime
#define sched_exp                       sum_exec_runtime

enum vtime_state {
        /* Task is sleeping or running in a CPU with VTIME inactive: */
        VTIME_INACTIVE = 0,
        /* Task runs in userspace in a CPU with VTIME active: */
        VTIME_USER,
        /* Task runs in kernelspace in a CPU with VTIME active: */
        VTIME_SYS,
};

struct vtime {
        seqcount_t              seqcount;
        unsigned long long      starttime;
        enum vtime_state        state;
        u64                     utime;
        u64                     stime;
        u64                     gtime;
};

/*
 * Utilization clamp constraints.
 * @UCLAMP_MIN: Minimum utilization
 * @UCLAMP_MAX: Maximum utilization
 * @UCLAMP_CNT: Utilization clamp constraints count
 */
enum uclamp_id {
        UCLAMP_MIN = 0,
        UCLAMP_MAX,
        UCLAMP_CNT
};

struct sched_info {
#ifdef CONFIG_SCHED_INFO
        /* Cumulative counters: */

        /* # of times we have run on this CPU: */
        unsigned long                   pcount;

        /* Time spent waiting on a runqueue: */
        unsigned long long              run_delay;

        /* Timestamps: */

        /* When did we last run on a CPU? */
        unsigned long long              last_arrival;

        /* When were we last queued to run? */
        unsigned long long              last_queued;

#endif /* CONFIG_SCHED_INFO */
};

/*
 * Integer metrics need fixed point arithmetic, e.g., sched/fair
 * has a few: load, load_avg, util_avg, freq, and capacity.
 *
 * We define a basic fixed point arithmetic range, and then formalize
 * all these metrics based on that basic range.
 */
# define SCHED_FIXEDPOINT_SHIFT         10
# define SCHED_FIXEDPOINT_SCALE         (1L << SCHED_FIXEDPOINT_SHIFT)

/* Increase resolution of cpu_capacity calculations */
# define SCHED_CAPACITY_SHIFT           SCHED_FIXEDPOINT_SHIFT
# define SCHED_CAPACITY_SCALE           (1L << SCHED_CAPACITY_SHIFT)

struct load_weight {
        unsigned long                   weight;
        u32                             inv_weight;
};

/**
 * struct util_est - Estimation utilization of FAIR tasks
 * @enqueued: instantaneous estimated utilization of a task/cpu
 * @ewma:     the Exponential Weighted Moving Average (EWMA)
 *            utilization of a task
 *
 * Support data structure to track an Exponential Weighted Moving Average
 * (EWMA) of a FAIR task's utilization. New samples are added to the moving
 * average each time a task completes an activation. Sample's weight is chosen
 * so that the EWMA will be relatively insensitive to transient changes to the
 * task's workload.
 *
 * The enqueued attribute has a slightly different meaning for tasks and cpus:
 * - task:   the task's util_avg at last task dequeue time
 * - cfs_rq: the sum of util_est.enqueued for each RUNNABLE task on that CPU
 * Thus, the util_est.enqueued of a task represents the contribution on the
 * estimated utilization of the CPU where that task is currently enqueued.
 *
 * Only for tasks we track a moving average of the past instantaneous
 * estimated utilization. This allows to absorb sporadic drops in utilization
 * of an otherwise almost periodic task.
 */
struct util_est {
        unsigned int                    enqueued;
        unsigned int                    ewma;
#define UTIL_EST_WEIGHT_SHIFT           2
} __attribute__((__aligned__(sizeof(u64))));

/*
 * The load_avg/util_avg accumulates an infinite geometric series
 * (see __update_load_avg() in kernel/sched/fair.c).
 *
 * [load_avg definition]
 *
 *   load_avg = runnable% * scale_load_down(load)
 *
 * where runnable% is the time ratio that a sched_entity is runnable.
 * For cfs_rq, it is the aggregated load_avg of all runnable and
 * blocked sched_entities.
 *
 * [util_avg definition]
 *
 *   util_avg = running% * SCHED_CAPACITY_SCALE
 *
 * where running% is the time ratio that a sched_entity is running on
 * a CPU. For cfs_rq, it is the aggregated util_avg of all runnable
 * and blocked sched_entities.
 *
 * load_avg and util_avg don't direcly factor frequency scaling and CPU
 * capacity scaling. The scaling is done through the rq_clock_pelt that
 * is used for computing those signals (see update_rq_clock_pelt())
 *
 * N.B., the above ratios (runnable% and running%) themselves are in the
 * range of [0, 1]. To do fixed point arithmetics, we therefore scale them
 * to as large a range as necessary. This is for example reflected by
 * util_avg's SCHED_CAPACITY_SCALE.
 *
 * [Overflow issue]
 *
 * The 64-bit load_sum can have 4353082796 (=2^64/47742/88761) entities
 * with the highest load (=88761), always runnable on a single cfs_rq,
 * and should not overflow as the number already hits PID_MAX_LIMIT.
 *
 * For all other cases (including 32-bit kernels), struct load_weight's
 * weight will overflow first before we do, because:
 *
 *    Max(load_avg) <= Max(load.weight)
 *
 * Then it is the load_weight's responsibility to consider overflow
 * issues.
 */
struct sched_avg {
        u64                             last_update_time;
        u64                             load_sum;
        u64                             runnable_load_sum;
        u32                             util_sum;
        u32                             period_contrib;
        unsigned long                   load_avg;
        unsigned long                   runnable_load_avg;
        unsigned long                   util_avg;
        struct util_est                 util_est;
} ____cacheline_aligned;

struct sched_statistics {
#ifdef CONFIG_SCHEDSTATS
        u64                             wait_start;
        u64                             wait_max;
        u64                             wait_count;
        u64                             wait_sum;
        u64                             iowait_count;
        u64                             iowait_sum;

        u64                             sleep_start;
        u64                             sleep_max;
        s64                             sum_sleep_runtime;

        u64                             block_start;
        u64                             block_max;
        u64                             exec_max;
        u64                             slice_max;

        u64                             nr_migrations_cold;
        u64                             nr_failed_migrations_affine;
        u64                             nr_failed_migrations_running;
        u64                             nr_failed_migrations_hot;
        u64                             nr_forced_migrations;

        u64                             nr_wakeups;
        u64                             nr_wakeups_sync;
        u64                             nr_wakeups_migrate;
        u64                             nr_wakeups_local;
        u64                             nr_wakeups_remote;
        u64                             nr_wakeups_affine;
        u64                             nr_wakeups_affine_attempts;
        u64                             nr_wakeups_passive;
        u64                             nr_wakeups_idle;
#endif
};

struct sched_entity {
        /* For load-balancing: */
        struct load_weight              load;
        unsigned long                   runnable_weight;
        struct rb_node                  run_node;
        struct list_head                group_node;
        unsigned int                    on_rq;

        u64                             exec_start;
        u64                             sum_exec_runtime;
        u64                             vruntime;
        u64                             prev_sum_exec_runtime;

        u64                             nr_migrations;

        struct sched_statistics         statistics;

#ifdef CONFIG_FAIR_GROUP_SCHED
        int                             depth;
        struct sched_entity             *parent;
        /* rq on which this entity is (to be) queued: */
        struct cfs_rq                   *cfs_rq;
        /* rq "owned" by this entity/group: */
        struct cfs_rq                   *my_q;
#endif

#ifdef CONFIG_SMP
        /*
         * Per entity load average tracking.
         *
         * Put into separate cache line so it does not
         * collide with read-mostly values above.
         */
        struct sched_avg                avg;
#endif
};

struct sched_rt_entity {
        struct list_head                run_list;
        unsigned long                   timeout;
        unsigned long                   watchdog_stamp;
        unsigned int                    time_slice;
        unsigned short                  on_rq;
        unsigned short                  on_list;

        struct sched_rt_entity          *back;
#ifdef CONFIG_RT_GROUP_SCHED
        struct sched_rt_entity          *parent;
        /* rq on which this entity is (to be) queued: */
        struct rt_rq                    *rt_rq;
        /* rq "owned" by this entity/group: */
        struct rt_rq                    *my_q;
#endif
} __randomize_layout;

struct sched_dl_entity {
        struct rb_node                  rb_node;

        /*
         * Original scheduling parameters. Copied here from sched_attr
         * during sched_setattr(), they will remain the same until
         * the next sched_setattr().
         */
        u64                             dl_runtime;     /* Maximum runtime for each instance    */
        u64                             dl_deadline;    /* Relative deadline of each instance   */
        u64                             dl_period;      /* Separation of two instances (period) */
        u64                             dl_bw;          /* dl_runtime / dl_period               */
        u64                             dl_density;     /* dl_runtime / dl_deadline             */

        /*
         * Actual scheduling parameters. Initialized with the values above,
         * they are continuously updated during task execution. Note that
         * the remaining runtime could be < 0 in case we are in overrun.
         */
        s64                             runtime;        /* Remaining runtime for this instance  */
        u64                             deadline;       /* Absolute deadline for this instance  */
        unsigned int                    flags;          /* Specifying the scheduler behaviour   */

        /*
         * Some bool flags:
         *
         * @dl_throttled tells if we exhausted the runtime. If so, the
         * task has to wait for a replenishment to be performed at the
         * next firing of dl_timer.
         *
         * @dl_boosted tells if we are boosted due to DI. If so we are
         * outside bandwidth enforcement mechanism (but only until we
         * exit the critical section);
         *
         * @dl_yielded tells if task gave up the CPU before consuming
         * all its available runtime during the last job.
         *
         * @dl_non_contending tells if the task is inactive while still
         * contributing to the active utilization. In other words, it
         * indicates if the inactive timer has been armed and its handler
         * has not been executed yet. This flag is useful to avoid race
         * conditions between the inactive timer handler and the wakeup
         * code.
         *
         * @dl_overrun tells if the task asked to be informed about runtime
         * overruns.
         */
        unsigned int                    dl_throttled      : 1;
        unsigned int                    dl_boosted        : 1;
        unsigned int                    dl_yielded        : 1;
        unsigned int                    dl_non_contending : 1;
        unsigned int                    dl_overrun        : 1;

        /*
         * Bandwidth enforcement timer. Each -deadline task has its
         * own bandwidth to be enforced, thus we need one timer per task.
         */
        struct hrtimer                  dl_timer;

        /*
         * Inactive timer, responsible for decreasing the active utilization
         * at the "0-lag time". When a -deadline task blocks, it contributes
         * to GRUB's active utilization until the "0-lag time", hence a
         * timer is needed to decrease the active utilization at the correct
         * time.
         */
        struct hrtimer inactive_timer;
};

#ifdef CONFIG_UCLAMP_TASK
/* Number of utilization clamp buckets (shorter alias) */
#define UCLAMP_BUCKETS CONFIG_UCLAMP_BUCKETS_COUNT

/*
 * Utilization clamp for a scheduling entity
 * @value:              clamp value "assigned" to a se
 * @bucket_id:          bucket index corresponding to the "assigned" value
 * @active:             the se is currently refcounted in a rq's bucket
 * @user_defined:       the requested clamp value comes from user-space
 *
 * The bucket_id is the index of the clamp bucket matching the clamp value
 * which is pre-computed and stored to avoid expensive integer divisions from
 * the fast path.
 *
 * The active bit is set whenever a task has got an "effective" value assigned,
 * which can be different from the clamp value "requested" from user-space.
 * This allows to know a task is refcounted in the rq's bucket corresponding
 * to the "effective" bucket_id.
 *
 * The user_defined bit is set whenever a task has got a task-specific clamp
 * value requested from userspace, i.e. the system defaults apply to this task
 * just as a restriction. This allows to relax default clamps when a less
 * restrictive task-specific value has been requested, thus allowing to
 * implement a "nice" semantic. For example, a task running with a 20%
 * default boost can still drop its own boosting to 0%.
 */
struct uclamp_se {
        unsigned int value              : bits_per(SCHED_CAPACITY_SCALE);
        unsigned int bucket_id          : bits_per(UCLAMP_BUCKETS);
        unsigned int active             : 1;
        unsigned int user_defined       : 1;
};
#endif /* CONFIG_UCLAMP_TASK */

union rcu_special {
        struct {
                u8                      blocked;
                u8                      need_qs;
                u8                      exp_hint; /* Hint for performance. */
                u8                      deferred_qs;
        } b; /* Bits. */
        u32 s; /* Set of bits. */
};

enum perf_event_task_context {
        perf_invalid_context = -1,
        perf_hw_context = 0,
        perf_sw_context,
        perf_nr_task_contexts,
};

struct wake_q_node {
        struct wake_q_node *next;
};

struct task_struct {
#ifdef CONFIG_THREAD_INFO_IN_TASK
        /*
         * For reasons of header soup (see current_thread_info()), this
         * must be the first element of task_struct.
         */
        struct thread_info              thread_info;
#endif
        /* -1 unrunnable, 0 runnable, >0 stopped: */
        volatile long                   state;

        /*
         * This begins the randomizable portion of task_struct. Only
         * scheduling-critical items should be added above here.
         */
        randomized_struct_fields_start

        void                            *stack;
        refcount_t                      usage;
        /* Per task flags (PF_*), defined further below: */
        unsigned int                    flags;
        unsigned int                    ptrace;

#ifdef CONFIG_SMP
        struct llist_node               wake_entry;
        int                             on_cpu;
#ifdef CONFIG_THREAD_INFO_IN_TASK
        /* Current CPU: */
        unsigned int                    cpu;
#endif
        unsigned int                    wakee_flips;
        unsigned long                   wakee_flip_decay_ts;
        struct task_struct              *last_wakee;

        /*
         * recent_used_cpu is initially set as the last CPU used by a task
         * that wakes affine another task. Waker/wakee relationships can
         * push tasks around a CPU where each wakeup moves to the next one.
         * Tracking a recently used CPU allows a quick search for a recently
         * used CPU that may be idle.
         */
        int                             recent_used_cpu;
        int                             wake_cpu;
#endif
        int                             on_rq;

        int                             prio;
        int                             static_prio;
        int                             normal_prio;
        unsigned int                    rt_priority;

        const struct sched_class        *sched_class;
        struct sched_entity             se;
        struct sched_rt_entity          rt;
#ifdef CONFIG_CGROUP_SCHED
        struct task_group               *sched_task_group;
#endif
        struct sched_dl_entity          dl;

#ifdef CONFIG_UCLAMP_TASK
        /* Clamp values requested for a scheduling entity */
        struct uclamp_se                uclamp_req[UCLAMP_CNT];
        /* Effective clamp values used for a scheduling entity */
        struct uclamp_se                uclamp[UCLAMP_CNT];
#endif

#ifdef CONFIG_PREEMPT_NOTIFIERS
        /* List of struct preempt_notifier: */
        struct hlist_head               preempt_notifiers;
#endif

#ifdef CONFIG_BLK_DEV_IO_TRACE
        unsigned int                    btrace_seq;
#endif

        unsigned int                    policy;
        int                             nr_cpus_allowed;
        const cpumask_t                 *cpus_ptr;
        cpumask_t                       cpus_mask;

#ifdef CONFIG_PREEMPT_RCU
        int                             rcu_read_lock_nesting;
        union rcu_special               rcu_read_unlock_special;
        struct list_head                rcu_node_entry;
        struct rcu_node                 *rcu_blocked_node;
#endif /* #ifdef CONFIG_PREEMPT_RCU */

#ifdef CONFIG_TASKS_RCU
        unsigned long                   rcu_tasks_nvcsw;
        u8                              rcu_tasks_holdout;
        u8                              rcu_tasks_idx;
        int                             rcu_tasks_idle_cpu;
        struct list_head                rcu_tasks_holdout_list;
#endif /* #ifdef CONFIG_TASKS_RCU */

        struct sched_info               sched_info;

        struct list_head                tasks;
#ifdef CONFIG_SMP
        struct plist_node               pushable_tasks;
        struct rb_node                  pushable_dl_tasks;
#endif

        struct mm_struct                *mm;
        struct mm_struct                *active_mm;

        /* Per-thread vma caching: */
        struct vmacache                 vmacache;

#ifdef SPLIT_RSS_COUNTING
        struct task_rss_stat            rss_stat;
#endif
        int                             exit_state;
        int                             exit_code;
        int                             exit_signal;
        /* The signal sent when the parent dies: */
        int                             pdeath_signal;
        /* JOBCTL_*, siglock protected: */
        unsigned long                   jobctl;

        /* Used for emulating ABI behavior of previous Linux versions: */
        unsigned int                    personality;

        /* Scheduler bits, serialized by scheduler locks: */
        unsigned                        sched_reset_on_fork:1;
        unsigned                        sched_contributes_to_load:1;
        unsigned                        sched_migrated:1;
        unsigned                        sched_remote_wakeup:1;
#ifdef CONFIG_PSI
        unsigned                        sched_psi_wake_requeue:1;
#endif

        /* Force alignment to the next boundary: */
        unsigned                        :0;

        /* Unserialized, strictly 'current' */

        /* Bit to tell LSMs we're in execve(): */
        unsigned                        in_execve:1;
        unsigned                        in_iowait:1;
#ifndef TIF_RESTORE_SIGMASK
        unsigned                        restore_sigmask:1;
#endif
#ifdef CONFIG_MEMCG
        unsigned                        in_user_fault:1;
#endif
#ifdef CONFIG_COMPAT_BRK
        unsigned                        brk_randomized:1;
#endif
#ifdef CONFIG_CGROUPS
        /* disallow userland-initiated cgroup migration */
        unsigned                        no_cgroup_migration:1;
        /* task is frozen/stopped (used by the cgroup freezer) */
        unsigned                        frozen:1;
#endif
#ifdef CONFIG_BLK_CGROUP
        /* to be used once the psi infrastructure lands upstream. */
        unsigned                        use_memdelay:1;
#endif

        unsigned long                   atomic_flags; /* Flags requiring atomic access. */

        struct restart_block            restart_block;

        pid_t                           pid;
        pid_t                           tgid;

#ifdef CONFIG_STACKPROTECTOR
        /* Canary value for the -fstack-protector GCC feature: */
        unsigned long                   stack_canary;
#endif
        /*
         * Pointers to the (original) parent process, youngest child, younger sibling,
         * older sibling, respectively.  (p->father can be replaced with
         * p->real_parent->pid)
         */

        /* Real parent process: */
        struct task_struct __rcu        *real_parent;

        /* Recipient of SIGCHLD, wait4() reports: */
        struct task_struct __rcu        *parent;

        /*
         * Children/sibling form the list of natural children:
         */
        struct list_head                children;
        struct list_head                sibling;
        struct task_struct              *group_leader;

        /*
         * 'ptraced' is the list of tasks this task is using ptrace() on.
         *
         * This includes both natural children and PTRACE_ATTACH targets.
         * 'ptrace_entry' is this task's link on the p->parent->ptraced list.
         */
        struct list_head                ptraced;
        struct list_head                ptrace_entry;

        /* PID/PID hash table linkage. */
        struct pid                      *thread_pid;
        struct hlist_node               pid_links[PIDTYPE_MAX];
        struct list_head                thread_group;
        struct list_head                thread_node;

        struct completion               *vfork_done;

        /* CLONE_CHILD_SETTID: */
        int __user                      *set_child_tid;

        /* CLONE_CHILD_CLEARTID: */
        int __user                      *clear_child_tid;

        u64                             utime;
        u64                             stime;
#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
        u64                             utimescaled;
        u64                             stimescaled;
#endif
        u64                             gtime;
        struct prev_cputime             prev_cputime;
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
        struct vtime                    vtime;
#endif

#ifdef CONFIG_NO_HZ_FULL
        atomic_t                        tick_dep_mask;
#endif
        /* Context switch counts: */
        unsigned long                   nvcsw;
        unsigned long                   nivcsw;

        /* Monotonic time in nsecs: */
        u64                             start_time;

        /* Boot based time in nsecs: */
        u64                             real_start_time;

        /* MM fault and swap info: this can arguably be seen as either mm-specific or thread-specific: */
        unsigned long                   min_flt;
        unsigned long                   maj_flt;

#ifdef CONFIG_POSIX_TIMERS
        struct task_cputime             cputime_expires;
        struct list_head                cpu_timers[3];
#endif

        /* Process credentials: */

        /* Tracer's credentials at attach: */
        const struct cred __rcu         *ptracer_cred;

        /* Objective and real subjective task credentials (COW): */
        const struct cred __rcu         *real_cred;

        /* Effective (overridable) subjective task credentials (COW): */
        const struct cred __rcu         *cred;

#ifdef CONFIG_KEYS
        /* Cached requested key. */
        struct key                      *cached_requested_key;
#endif

        /*
         * executable name, excluding path.
         *
         * - normally initialized setup_new_exec()
         * - access it with [gs]et_task_comm()
         * - lock it with task_lock()
         */
        char                            comm[TASK_COMM_LEN];

        struct nameidata                *nameidata;

#ifdef CONFIG_SYSVIPC
        struct sysv_sem                 sysvsem;
        struct sysv_shm                 sysvshm;
#endif
#ifdef CONFIG_DETECT_HUNG_TASK
        unsigned long                   last_switch_count;
        unsigned long                   last_switch_time;
#endif
        /* Filesystem information: */
        struct fs_struct                *fs;

        /* Open file information: */
        struct files_struct             *files;

        /* Namespaces: */
        struct nsproxy                  *nsproxy;

        /* Signal handlers: */
        struct signal_struct            *signal;
        struct sighand_struct           *sighand;
        sigset_t                        blocked;
        sigset_t                        real_blocked;
        /* Restored if set_restore_sigmask() was used: */
        sigset_t                        saved_sigmask;
        struct sigpending               pending;
        unsigned long                   sas_ss_sp;
        size_t                          sas_ss_size;
        unsigned int                    sas_ss_flags;

        struct callback_head            *task_works;

#ifdef CONFIG_AUDIT
#ifdef CONFIG_AUDITSYSCALL
        struct audit_context            *audit_context;
#endif
        kuid_t                          loginuid;
        unsigned int                    sessionid;
#endif
        struct seccomp                  seccomp;

        /* Thread group tracking: */
        u32                             parent_exec_id;
        u32                             self_exec_id;

        /* Protection against (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, mempolicy: */
        spinlock_t                      alloc_lock;

        /* Protection of the PI data structures: */
        raw_spinlock_t                  pi_lock;

        struct wake_q_node              wake_q;

#ifdef CONFIG_RT_MUTEXES
        /* PI waiters blocked on a rt_mutex held by this task: */
        struct rb_root_cached           pi_waiters;
        /* Updated under owner's pi_lock and rq lock */
        struct task_struct              *pi_top_task;
        /* Deadlock detection and priority inheritance handling: */
        struct rt_mutex_waiter          *pi_blocked_on;
#endif

#ifdef CONFIG_DEBUG_MUTEXES
        /* Mutex deadlock detection: */
        struct mutex_waiter             *blocked_on;
#endif

#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
        int                             non_block_count;
#endif

#ifdef CONFIG_TRACE_IRQFLAGS
        unsigned int                    irq_events;
        unsigned long                   hardirq_enable_ip;
        unsigned long                   hardirq_disable_ip;
        unsigned int                    hardirq_enable_event;
        unsigned int                    hardirq_disable_event;
        int                             hardirqs_enabled;
        int                             hardirq_context;
        unsigned long                   softirq_disable_ip;
        unsigned long                   softirq_enable_ip;
        unsigned int                    softirq_disable_event;
        unsigned int                    softirq_enable_event;
        int                             softirqs_enabled;
        int                             softirq_context;
#endif

#ifdef CONFIG_LOCKDEP
# define MAX_LOCK_DEPTH                 48UL
        u64                             curr_chain_key;
        int                             lockdep_depth;
        unsigned int                    lockdep_recursion;
        struct held_lock                held_locks[MAX_LOCK_DEPTH];
#endif

#ifdef CONFIG_UBSAN
        unsigned int                    in_ubsan;
#endif

        /* Journalling filesystem info: */
        void                            *journal_info;

        /* Stacked block device info: */
        struct bio_list                 *bio_list;

#ifdef CONFIG_BLOCK
        /* Stack plugging: */
        struct blk_plug                 *plug;
#endif

        /* VM state: */
        struct reclaim_state            *reclaim_state;

        struct backing_dev_info         *backing_dev_info;

        struct io_context               *io_context;

#ifdef CONFIG_COMPACTION
        struct capture_control          *capture_control;
#endif
        /* Ptrace state: */
        unsigned long                   ptrace_message;
        kernel_siginfo_t                *last_siginfo;

        struct task_io_accounting       ioac;
#ifdef CONFIG_PSI
        /* Pressure stall state */
        unsigned int                    psi_flags;
#endif
#ifdef CONFIG_TASK_XACCT
        /* Accumulated RSS usage: */
        u64                             acct_rss_mem1;
        /* Accumulated virtual memory usage: */
        u64                             acct_vm_mem1;
        /* stime + utime since last update: */
        u64                             acct_timexpd;
#endif
#ifdef CONFIG_CPUSETS
        /* Protected by ->alloc_lock: */
        nodemask_t                      mems_allowed;
        /* Seqence number to catch updates: */
        seqcount_t                      mems_allowed_seq;
        int                             cpuset_mem_spread_rotor;
        int                             cpuset_slab_spread_rotor;
#endif
#ifdef CONFIG_CGROUPS
        /* Control Group info protected by css_set_lock: */
        struct css_set __rcu            *cgroups;
        /* cg_list protected by css_set_lock and tsk->alloc_lock: */
        struct list_head                cg_list;
#endif
#ifdef CONFIG_X86_CPU_RESCTRL
        u32                             closid;
        u32                             rmid;
#endif
#ifdef CONFIG_FUTEX
        struct robust_list_head __user  *robust_list;
#ifdef CONFIG_COMPAT
        struct compat_robust_list_head __user *compat_robust_list;
#endif
        struct list_head                pi_state_list;
        struct futex_pi_state           *pi_state_cache;
#endif
#ifdef CONFIG_PERF_EVENTS
        struct perf_event_context       *perf_event_ctxp[perf_nr_task_contexts];
        struct mutex                    perf_event_mutex;
        struct list_head                perf_event_list;
#endif
#ifdef CONFIG_DEBUG_PREEMPT
        unsigned long                   preempt_disable_ip;
#endif
#ifdef CONFIG_NUMA
        /* Protected by alloc_lock: */
        struct mempolicy                *mempolicy;
        short                           il_prev;
        short                           pref_node_fork;
#endif
#ifdef CONFIG_NUMA_BALANCING
        int                             numa_scan_seq;
        unsigned int                    numa_scan_period;
        unsigned int                    numa_scan_period_max;
        int                             numa_preferred_nid;
        unsigned long                   numa_migrate_retry;
        /* Migration stamp: */
        u64                             node_stamp;
        u64                             last_task_numa_placement;
        u64                             last_sum_exec_runtime;
        struct callback_head            numa_work;

        /*
         * This pointer is only modified for current in syscall and
         * pagefault context (and for tasks being destroyed), so it can be read
         * from any of the following contexts:
         *  - RCU read-side critical section
         *  - current->numa_group from everywhere
         *  - task's runqueue locked, task not running
         */
        struct numa_group __rcu         *numa_group;

        /*
         * numa_faults is an array split into four regions:
         * faults_memory, faults_cpu, faults_memory_buffer, faults_cpu_buffer
         * in this precise order.
         *
         * faults_memory: Exponential decaying average of faults on a per-node
         * basis. Scheduling placement decisions are made based on these
         * counts. The values remain static for the duration of a PTE scan.
         * faults_cpu: Track the nodes the process was running on when a NUMA
         * hinting fault was incurred.
         * faults_memory_buffer and faults_cpu_buffer: Record faults per node
         * during the current scan window. When the scan completes, the counts
         * in faults_memory and faults_cpu decay and these values are copied.
         */
        unsigned long                   *numa_faults;
        unsigned long                   total_numa_faults;

        /*
         * numa_faults_locality tracks if faults recorded during the last
         * scan window were remote/local or failed to migrate. The task scan
         * period is adapted based on the locality of the faults with different
         * weights depending on whether they were shared or private faults
         */
        unsigned long                   numa_faults_locality[3];

        unsigned long                   numa_pages_migrated;
#endif /* CONFIG_NUMA_BALANCING */

#ifdef CONFIG_RSEQ
        struct rseq __user *rseq;
        u32 rseq_sig;
        /*
         * RmW on rseq_event_mask must be performed atomically
         * with respect to preemption.
         */
        unsigned long rseq_event_mask;
#endif

        struct tlbflush_unmap_batch     tlb_ubc;

        struct rcu_head                 rcu;

        /* Cache last used pipe for splice(): */
        struct pipe_inode_info          *splice_pipe;

        struct page_frag                task_frag;

#ifdef CONFIG_TASK_DELAY_ACCT
        struct task_delay_info          *delays;
#endif

#ifdef CONFIG_FAULT_INJECTION
        int                             make_it_fail;
        unsigned int                    fail_nth;
#endif
        /*
         * When (nr_dirtied >= nr_dirtied_pause), it's time to call
         * balance_dirty_pages() for a dirty throttling pause:
         */
        int                             nr_dirtied;
        int                             nr_dirtied_pause;
        /* Start of a write-and-pause period: */
        unsigned long                   dirty_paused_when;

#ifdef CONFIG_LATENCYTOP
        int                             latency_record_count;
        struct latency_record           latency_record[LT_SAVECOUNT];
#endif
        /*
         * Time slack values; these are used to round up poll() and
         * select() etc timeout values. These are in nanoseconds.
         */
        u64                             timer_slack_ns;
        u64                             default_timer_slack_ns;

#ifdef CONFIG_KASAN
        unsigned int                    kasan_depth;
#endif

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        /* Index of current stored address in ret_stack: */
        int                             curr_ret_stack;
        int                             curr_ret_depth;

        /* Stack of return addresses for return function tracing: */
        struct ftrace_ret_stack         *ret_stack;

        /* Timestamp for last schedule: */
        unsigned long long              ftrace_timestamp;

        /*
         * Number of functions that haven't been traced
         * because of depth overrun:
         */
        atomic_t                        trace_overrun;

        /* Pause tracing: */
        atomic_t                        tracing_graph_pause;
#endif

#ifdef CONFIG_TRACING
        /* State flags for use by tracers: */
        unsigned long                   trace;

        /* Bitmask and counter of trace recursion: */
        unsigned long                   trace_recursion;
#endif /* CONFIG_TRACING */

#ifdef CONFIG_KCOV
        /* Coverage collection mode enabled for this task (0 if disabled): */
        unsigned int                    kcov_mode;

        /* Size of the kcov_area: */
        unsigned int                    kcov_size;

        /* Buffer for coverage collection: */
        void                            *kcov_area;

        /* KCOV descriptor wired with this task or NULL: */
        struct kcov                     *kcov;
#endif

#ifdef CONFIG_MEMCG
        struct mem_cgroup               *memcg_in_oom;
        gfp_t                           memcg_oom_gfp_mask;
        int                             memcg_oom_order;

        /* Number of pages to reclaim on returning to userland: */
        unsigned int                    memcg_nr_pages_over_high;

        /* Used by memcontrol for targeted memcg charge: */
        struct mem_cgroup               *active_memcg;
#endif

#ifdef CONFIG_BLK_CGROUP
        struct request_queue            *throttle_queue;
#endif

#ifdef CONFIG_UPROBES
        struct uprobe_task              *utask;
#endif
#if defined(CONFIG_BCACHE) || defined(CONFIG_BCACHE_MODULE)
        unsigned int                    sequential_io;
        unsigned int                    sequential_io_avg;
#endif
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
        unsigned long                   task_state_change;
#endif
        int                             pagefault_disabled;
#ifdef CONFIG_MMU
        struct task_struct              *oom_reaper_list;
#endif
#ifdef CONFIG_VMAP_STACK
        struct vm_struct                *stack_vm_area;
#endif
#ifdef CONFIG_THREAD_INFO_IN_TASK
        /* A live task holds one reference: */
        refcount_t                      stack_refcount;
#endif
#ifdef CONFIG_LIVEPATCH
        int patch_state;
#endif
#ifdef CONFIG_SECURITY
        /* Used by LSM modules for access restriction: */
        void                            *security;
#endif

#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
        unsigned long                   lowest_stack;
        unsigned long                   prev_lowest_stack;
#endif

        /*
         * New fields for task_struct should be added above here, so that
         * they are included in the randomized portion of task_struct.
         */
        randomized_struct_fields_end

        /* CPU-specific state of this task: */
        struct thread_struct            thread;

        /*
         * WARNING: on x86, 'thread_struct' contains a variable-sized
         * structure.  It *MUST* be at the end of 'task_struct'.
         *
         * Do not put anything below here!
         */
};

static inline struct pid *task_pid(struct task_struct *task)
{
        return task->thread_pid;
}

/*
 * the helpers to get the task's different pids as they are seen
 * from various namespaces
 *
 * task_xid_nr()     : global id, i.e. the id seen from the init namespace;
 * task_xid_vnr()    : virtual id, i.e. the id seen from the pid namespace of
 *                     current.
 * task_xid_nr_ns()  : id seen from the ns specified;
 *
 * see also pid_nr() etc in include/linux/pid.h
 */
pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, struct pid_namespace *ns);

static inline pid_t task_pid_nr(struct task_struct *tsk)
{
        return tsk->pid;
}

static inline pid_t task_pid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
}

static inline pid_t task_pid_vnr(struct task_struct *tsk)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_PID, NULL);
}


static inline pid_t task_tgid_nr(struct task_struct *tsk)
{
        return tsk->tgid;
}

/**
 * pid_alive - check that a task structure is not stale
 * @p: Task structure to be checked.
 *
 * Test if a process is not yet dead (at most zombie state)
 * If pid_alive fails, then pointers within the task structure
 * can be stale and must not be dereferenced.
 *
 * Return: 1 if the process is alive. 0 otherwise.
 */
static inline int pid_alive(const struct task_struct *p)
{
        return p->thread_pid != NULL;
}

static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_PGID, ns);
}

static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_PGID, NULL);
}


static inline pid_t task_session_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_SID, ns);
}

static inline pid_t task_session_vnr(struct task_struct *tsk)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_SID, NULL);
}

static inline pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_TGID, ns);
}

static inline pid_t task_tgid_vnr(struct task_struct *tsk)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_TGID, NULL);
}

static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct pid_namespace *ns)
{
        pid_t pid = 0;

        rcu_read_lock();
        if (pid_alive(tsk))
                pid = task_tgid_nr_ns(rcu_dereference(tsk->real_parent), ns);
        rcu_read_unlock();

        return pid;
}

static inline pid_t task_ppid_nr(const struct task_struct *tsk)
{
        return task_ppid_nr_ns(tsk, &init_pid_ns);
}

/* Obsolete, do not use: */
static inline pid_t task_pgrp_nr(struct task_struct *tsk)
{
        return task_pgrp_nr_ns(tsk, &init_pid_ns);
}

#define TASK_REPORT_IDLE        (TASK_REPORT + 1)
#define TASK_REPORT_MAX         (TASK_REPORT_IDLE << 1)

static inline unsigned int task_state_index(struct task_struct *tsk)
{
        unsigned int tsk_state = READ_ONCE(tsk->state);
        unsigned int state = (tsk_state | tsk->exit_state) & TASK_REPORT;

        BUILD_BUG_ON_NOT_POWER_OF_2(TASK_REPORT_MAX);

        if (tsk_state == TASK_IDLE)
                state = TASK_REPORT_IDLE;

        return fls(state);
}

static inline char task_index_to_char(unsigned int state)
{
        static const char state_char[] = "RSDTtXZPI";

        BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != sizeof(state_char) - 1);

        return state_char[state];
}

static inline char task_state_to_char(struct task_struct *tsk)
{
        return task_index_to_char(task_state_index(tsk));
}

/**
 * is_global_init - check if a task structure is init. Since init
 * is free to have sub-threads we need to check tgid.
 * @tsk: Task structure to be checked.
 *
 * Check if a task structure is the first user space task the kernel created.
 *
 * Return: 1 if the task structure is init. 0 otherwise.
 */
static inline int is_global_init(struct task_struct *tsk)
{
        return task_tgid_nr(tsk) == 1;
}

extern struct pid *cad_pid;

/*
 * Per process flags
 */
#define PF_IDLE                 0x00000002      /* I am an IDLE thread */
#define PF_EXITING              0x00000004      /* Getting shut down */
#define PF_EXITPIDONE           0x00000008      /* PI exit done on shut down */
#define PF_VCPU                 0x00000010      /* I'm a virtual CPU */
#define PF_WQ_WORKER            0x00000020      /* I'm a workqueue worker */
#define PF_FORKNOEXEC           0x00000040      /* Forked but didn't exec */
#define PF_MCE_PROCESS          0x00000080      /* Process policy on mce errors */
#define PF_SUPERPRIV            0x00000100      /* Used super-user privileges */
#define PF_DUMPCORE             0x00000200      /* Dumped core */
#define PF_SIGNALED             0x00000400      /* Killed by a signal */
#define PF_MEMALLOC             0x00000800      /* Allocating memory */
#define PF_NPROC_EXCEEDED       0x00001000      /* set_user() noticed that RLIMIT_NPROC was exceeded */
#define PF_USED_MATH            0x00002000      /* If unset the fpu must be initialized before use */
#define PF_USED_ASYNC           0x00004000      /* Used async_schedule*(), used by module init */
#define PF_NOFREEZE             0x00008000      /* This thread should not be frozen */
#define PF_FROZEN               0x00010000      /* Frozen for system suspend */
#define PF_KSWAPD               0x00020000      /* I am kswapd */
#define PF_MEMALLOC_NOFS        0x00040000      /* All allocation requests will inherit GFP_NOFS */
#define PF_MEMALLOC_NOIO        0x00080000      /* All allocation requests will inherit GFP_NOIO */
#define PF_LESS_THROTTLE        0x00100000      /* Throttle me less: I clean memory */
#define PF_KTHREAD              0x00200000      /* I am a kernel thread */
#define PF_RANDOMIZE            0x00400000      /* Randomize virtual address space */
#define PF_SWAPWRITE            0x00800000      /* Allowed to write to swap */
#define PF_MEMSTALL             0x01000000      /* Stalled due to lack of memory */
#define PF_UMH                  0x02000000      /* I'm an Usermodehelper process */
#define PF_NO_SETAFFINITY       0x04000000      /* Userland is not allowed to meddle with cpus_mask */
#define PF_MCE_EARLY            0x08000000      /* Early kill for mce process policy */
#define PF_MEMALLOC_NOCMA       0x10000000      /* All allocation request will have _GFP_MOVABLE cleared */
#define PF_FREEZER_SKIP         0x40000000      /* Freezer should not count it as freezable */
#define PF_SUSPEND_TASK         0x80000000      /* This thread called freeze_processes() and should not be frozen */

/*
 * Only the _current_ task can read/write to tsk->flags, but other
 * tasks can access tsk->flags in readonly mode for example
 * with tsk_used_math (like during threaded core dumping).
 * There is however an exception to this rule during ptrace
 * or during fork: the ptracer task is allowed to write to the
 * child->flags of its traced child (same goes for fork, the parent
 * can write to the child->flags), because we're guaranteed the
 * child is not running and in turn not changing child->flags
 * at the same time the parent does it.
 */
#define clear_stopped_child_used_math(child)    do { (child)->flags &= ~PF_USED_MATH; } while (0)
#define set_stopped_child_used_math(child)      do { (child)->flags |= PF_USED_MATH; } while (0)
#define clear_used_math()                       clear_stopped_child_used_math(current)
#define set_used_math()                         set_stopped_child_used_math(current)

#define conditional_stopped_child_used_math(condition, child) \
        do { (child)->flags &= ~PF_USED_MATH, (child)->flags |= (condition) ? PF_USED_MATH : 0; } while (0)

#define conditional_used_math(condition)        conditional_stopped_child_used_math(condition, current)

#define copy_to_stopped_child_used_math(child) \
        do { (child)->flags &= ~PF_USED_MATH, (child)->flags |= current->flags & PF_USED_MATH; } while (0)

/* NOTE: this will return 0 or PF_USED_MATH, it will never return 1 */
#define tsk_used_math(p)                        ((p)->flags & PF_USED_MATH)
#define used_math()                             tsk_used_math(current)

static inline bool is_percpu_thread(void)
{
#ifdef CONFIG_SMP
        return (current->flags & PF_NO_SETAFFINITY) &&
                (current->nr_cpus_allowed  == 1);
#else
        return true;
#endif
}

/* Per-process atomic flags. */
#define PFA_NO_NEW_PRIVS                0       /* May not gain new privileges. */
#define PFA_SPREAD_PAGE                 1       /* Spread page cache over cpuset */
#define PFA_SPREAD_SLAB                 2       /* Spread some slab caches over cpuset */
#define PFA_SPEC_SSB_DISABLE            3       /* Speculative Store Bypass disabled */
#define PFA_SPEC_SSB_FORCE_DISABLE      4       /* Speculative Store Bypass force disabled*/
#define PFA_SPEC_IB_DISABLE             5       /* Indirect branch speculation restricted */
#define PFA_SPEC_IB_FORCE_DISABLE       6       /* Indirect branch speculation permanently restricted */
#define PFA_SPEC_SSB_NOEXEC             7       /* Speculative Store Bypass clear on execve() */

#define TASK_PFA_TEST(name, func)                                       \
        static inline bool task_##func(struct task_struct *p)           \
        { return test_bit(PFA_##name, &p->atomic_flags); }

#define TASK_PFA_SET(name, func)                                        \
        static inline void task_set_##func(struct task_struct *p)       \
        { set_bit(PFA_##name, &p->atomic_flags); }

#define TASK_PFA_CLEAR(name, func)                                      \
        static inline void task_clear_##func(struct task_struct *p)     \
        { clear_bit(PFA_##name, &p->atomic_flags); }

TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)

TASK_PFA_TEST(SPREAD_PAGE, spread_page)
TASK_PFA_SET(SPREAD_PAGE, spread_page)
TASK_PFA_CLEAR(SPREAD_PAGE, spread_page)

TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
TASK_PFA_SET(SPREAD_SLAB, spread_slab)
TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)

TASK_PFA_TEST(SPEC_SSB_DISABLE, spec_ssb_disable)
TASK_PFA_SET(SPEC_SSB_DISABLE, spec_ssb_disable)
TASK_PFA_CLEAR(SPEC_SSB_DISABLE, spec_ssb_disable)

TASK_PFA_TEST(SPEC_SSB_NOEXEC, spec_ssb_noexec)
TASK_PFA_SET(SPEC_SSB_NOEXEC, spec_ssb_noexec)
TASK_PFA_CLEAR(SPEC_SSB_NOEXEC, spec_ssb_noexec)

TASK_PFA_TEST(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable)
TASK_PFA_SET(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable)

TASK_PFA_TEST(SPEC_IB_DISABLE, spec_ib_disable)
TASK_PFA_SET(SPEC_IB_DISABLE, spec_ib_disable)
TASK_PFA_CLEAR(SPEC_IB_DISABLE, spec_ib_disable)

TASK_PFA_TEST(SPEC_IB_FORCE_DISABLE, spec_ib_force_disable)
TASK_PFA_SET(SPEC_IB_FORCE_DISABLE, spec_ib_force_disable)

static inline void
current_restore_flags(unsigned long orig_flags, unsigned long flags)
{
        current->flags &= ~flags;
        current->flags |= orig_flags & flags;
}

extern int cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial);
extern int task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed);
#ifdef CONFIG_SMP
extern void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask);
extern int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask);
#else
static inline void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
{
}
static inline int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
{
        if (!cpumask_test_cpu(0, new_mask))
                return -EINVAL;
        return 0;
}
#endif

extern int yield_to(struct task_struct *p, bool preempt);
extern void set_user_nice(struct task_struct *p, long nice);
extern int task_prio(const struct task_struct *p);

/**
 * task_nice - return the nice value of a given task.
 * @p: the task in question.
 *
 * Return: The nice value [ -20 ... 0 ... 19 ].
 */
static inline int task_nice(const struct task_struct *p)
{
        return PRIO_TO_NICE((p)->static_prio);
}

extern int can_nice(const struct task_struct *p, const int nice);
extern int task_curr(const struct task_struct *p);
extern int idle_cpu(int cpu);
extern int available_idle_cpu(int cpu);
extern int sched_setscheduler(struct task_struct *, int, const struct sched_param *);
extern int sched_setscheduler_nocheck(struct task_struct *, int, const struct sched_param *);
extern int sched_setattr(struct task_struct *, const struct sched_attr *);
extern int sched_setattr_nocheck(struct task_struct *, const struct sched_attr *);
extern struct task_struct *idle_task(int cpu);

/**
 * is_idle_task - is the specified task an idle task?
 * @p: the task in question.
 *
 * Return: 1 if @p is an idle task. 0 otherwise.
 */
static inline bool is_idle_task(const struct task_struct *p)
{
        return !!(p->flags & PF_IDLE);
}

extern struct task_struct *curr_task(int cpu);
extern void ia64_set_curr_task(int cpu, struct task_struct *p);

void yield(void);

union thread_union {
#ifndef CONFIG_ARCH_TASK_STRUCT_ON_STACK
        struct task_struct task;
#endif
#ifndef CONFIG_THREAD_INFO_IN_TASK
        struct thread_info thread_info;
#endif
        unsigned long stack[THREAD_SIZE/sizeof(long)];
};

#ifndef CONFIG_THREAD_INFO_IN_TASK
extern struct thread_info init_thread_info;
#endif

extern unsigned long init_stack[THREAD_SIZE / sizeof(unsigned long)];

#ifdef CONFIG_THREAD_INFO_IN_TASK
static inline struct thread_info *task_thread_info(struct task_struct *task)
{
        return &task->thread_info;
}
#elif !defined(__HAVE_THREAD_FUNCTIONS)
# define task_thread_info(task) ((struct thread_info *)(task)->stack)
#endif

/*
 * find a task by one of its numerical ids
 *
 * find_task_by_pid_ns():
 *      finds a task by its pid in the specified namespace
 * find_task_by_vpid():
 *      finds a task by its virtual pid
 *
 * see also find_vpid() etc in include/linux/pid.h
 */

extern struct task_struct *find_task_by_vpid(pid_t nr);
extern struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns);

/*
 * find a task by its virtual pid and get the task struct
 */
extern struct task_struct *find_get_task_by_vpid(pid_t nr);

extern int wake_up_state(struct task_struct *tsk, unsigned int state);
extern int wake_up_process(struct task_struct *tsk);
extern void wake_up_new_task(struct task_struct *tsk);

#ifdef CONFIG_SMP
extern void kick_process(struct task_struct *tsk);
#else
static inline void kick_process(struct task_struct *tsk) { }
#endif

extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec);

static inline void set_task_comm(struct task_struct *tsk, const char *from)
{
        __set_task_comm(tsk, from, false);
}

extern char *__get_task_comm(char *to, size_t len, struct task_struct *tsk);
#define get_task_comm(buf, tsk) ({                      \
        BUILD_BUG_ON(sizeof(buf) != TASK_COMM_LEN);     \
        __get_task_comm(buf, sizeof(buf), tsk);         \
})

#ifdef CONFIG_SMP
void scheduler_ipi(void);
extern unsigned long wait_task_inactive(struct task_struct *, long match_state);
#else
static inline void scheduler_ipi(void) { }
static inline unsigned long wait_task_inactive(struct task_struct *p, long match_state)
{
        return 1;
}
#endif

/*
 * Set thread flags in other task's structures.
 * See asm/thread_info.h for TIF_xxxx flags available:
 */
static inline void set_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        set_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline void clear_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        clear_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline void update_tsk_thread_flag(struct task_struct *tsk, int flag,
                                          bool value)
{
        update_ti_thread_flag(task_thread_info(tsk), flag, value);
}

static inline int test_and_set_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        return test_and_set_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline int test_and_clear_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        return test_and_clear_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline int test_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        return test_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline void set_tsk_need_resched(struct task_struct *tsk)
{
        set_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
}

static inline void clear_tsk_need_resched(struct task_struct *tsk)
{
        clear_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
}

static inline int test_tsk_need_resched(struct task_struct *tsk)
{
        return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED));
}

/*
 * cond_resched() and cond_resched_lock(): latency reduction via
 * explicit rescheduling in places that are safe. The return
 * value indicates whether a reschedule was done in fact.
 * cond_resched_lock() will drop the spinlock before scheduling,
 */
#ifndef CONFIG_PREEMPT
extern int _cond_resched(void);
#else
static inline int _cond_resched(void) { return 0; }
#endif

#define cond_resched() ({                       \
        ___might_sleep(__FILE__, __LINE__, 0);  \
        _cond_resched();                        \
})

extern int __cond_resched_lock(spinlock_t *lock);

#define cond_resched_lock(lock) ({                              \
        ___might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET);\
        __cond_resched_lock(lock);                              \
})

static inline void cond_resched_rcu(void)
{
#if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
        rcu_read_unlock();
        cond_resched();
        rcu_read_lock();
#endif
}

/*
 * Does a critical section need to be broken due to another
 * task waiting?: (technically does not depend on CONFIG_PREEMPT,
 * but a general need for low latency)
 */
static inline int spin_needbreak(spinlock_t *lock)
{
#ifdef CONFIG_PREEMPT
        return spin_is_contended(lock);
#else
        return 0;
#endif
}

static __always_inline bool need_resched(void)
{
        return unlikely(tif_need_resched());
}

/*
 * Wrappers for p->thread_info->cpu access. No-op on UP.
 */
#ifdef CONFIG_SMP

static inline unsigned int task_cpu(const struct task_struct *p)
{
#ifdef CONFIG_THREAD_INFO_IN_TASK
        return READ_ONCE(p->cpu);
#else
        return READ_ONCE(task_thread_info(p)->cpu);
#endif
}

extern void set_task_cpu(struct task_struct *p, unsigned int cpu);

#else

static inline unsigned int task_cpu(const struct task_struct *p)
{
        return 0;
}

static inline void set_task_cpu(struct task_struct *p, unsigned int cpu)
{
}

#endif /* CONFIG_SMP */

/*
 * In order to reduce various lock holder preemption latencies provide an
 * interface to see if a vCPU is currently running or not.
 *
 * This allows us to terminate optimistic spin loops and block, analogous to
 * the native optimistic spin heuristic of testing if the lock owner task is
 * running or not.
 */
#ifndef vcpu_is_preempted
# define vcpu_is_preempted(cpu) false
#endif

extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask);
extern long sched_getaffinity(pid_t pid, struct cpumask *mask);

#ifndef TASK_SIZE_OF
#define TASK_SIZE_OF(tsk)       TASK_SIZE
#endif

#ifdef CONFIG_RSEQ

/*
 * Map the event mask on the user-space ABI enum rseq_cs_flags
 * for direct mask checks.
 */
enum rseq_event_mask_bits {
        RSEQ_EVENT_PREEMPT_BIT  = RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT,
        RSEQ_EVENT_SIGNAL_BIT   = RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT,
        RSEQ_EVENT_MIGRATE_BIT  = RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT,
};

enum rseq_event_mask {
        RSEQ_EVENT_PREEMPT      = (1U << RSEQ_EVENT_PREEMPT_BIT),
        RSEQ_EVENT_SIGNAL       = (1U << RSEQ_EVENT_SIGNAL_BIT),
        RSEQ_EVENT_MIGRATE      = (1U << RSEQ_EVENT_MIGRATE_BIT),
};

static inline void rseq_set_notify_resume(struct task_struct *t)
{
        if (t->rseq)
                set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
}

void __rseq_handle_notify_resume(struct ksignal *sig, struct pt_regs *regs);

static inline void rseq_handle_notify_resume(struct ksignal *ksig,
                                             struct pt_regs *regs)
{
        if (current->rseq)
                __rseq_handle_notify_resume(ksig, regs);
}

static inline void rseq_signal_deliver(struct ksignal *ksig,
                                       struct pt_regs *regs)
{
        preempt_disable();
        __set_bit(RSEQ_EVENT_SIGNAL_BIT, &current->rseq_event_mask);
        preempt_enable();
        rseq_handle_notify_resume(ksig, regs);
}

/* rseq_preempt() requires preemption to be disabled. */
static inline void rseq_preempt(struct task_struct *t)
{
        __set_bit(RSEQ_EVENT_PREEMPT_BIT, &t->rseq_event_mask);
        rseq_set_notify_resume(t);
}

/* rseq_migrate() requires preemption to be disabled. */
static inline void rseq_migrate(struct task_struct *t)
{
        __set_bit(RSEQ_EVENT_MIGRATE_BIT, &t->rseq_event_mask);
        rseq_set_notify_resume(t);
}

/*
 * If parent process has a registered restartable sequences area, the
 * child inherits. Only applies when forking a process, not a thread.
 */
static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
{
        if (clone_flags & CLONE_THREAD) {
                t->rseq = NULL;
                t->rseq_sig = 0;
                t->rseq_event_mask = 0;
        } else {
                t->rseq = current->rseq;
                t->rseq_sig = current->rseq_sig;
                t->rseq_event_mask = current->rseq_event_mask;
        }
}

static inline void rseq_execve(struct task_struct *t)
{
        t->rseq = NULL;
        t->rseq_sig = 0;
        t->rseq_event_mask = 0;
}

#else

static inline void rseq_set_notify_resume(struct task_struct *t)
{
}
static inline void rseq_handle_notify_resume(struct ksignal *ksig,
                                             struct pt_regs *regs)
{
}
static inline void rseq_signal_deliver(struct ksignal *ksig,
                                       struct pt_regs *regs)
{
}
static inline void rseq_preempt(struct task_struct *t)
{
}
static inline void rseq_migrate(struct task_struct *t)
{
}
static inline void rseq_fork(struct task_struct *t, unsigned long clone_flags)
{
}
static inline void rseq_execve(struct task_struct *t)
{
}

#endif

void __exit_umh(struct task_struct *tsk);

static inline void exit_umh(struct task_struct *tsk)
{
        if (unlikely(tsk->flags & PF_UMH))
                __exit_umh(tsk);
}

#ifdef CONFIG_DEBUG_RSEQ

void rseq_syscall(struct pt_regs *regs);

#else

static inline void rseq_syscall(struct pt_regs *regs)
{
}

#endif

const struct sched_avg *sched_trace_cfs_rq_avg(struct cfs_rq *cfs_rq);
char *sched_trace_cfs_rq_path(struct cfs_rq *cfs_rq, char *str, int len);
int sched_trace_cfs_rq_cpu(struct cfs_rq *cfs_rq);

const struct sched_avg *sched_trace_rq_avg_rt(struct rq *rq);
const struct sched_avg *sched_trace_rq_avg_dl(struct rq *rq);
const struct sched_avg *sched_trace_rq_avg_irq(struct rq *rq);

int sched_trace_rq_cpu(struct rq *rq);

const struct cpumask *sched_trace_rd_span(struct root_domain *rd);

#endif