sched/core: Move, sort and clean up <linux/sched.h> structure predeclarations

[karo-tx-linux.git] / include / linux / sched.h

#ifndef _LINUX_SCHED_H
#define _LINUX_SCHED_H

#include <uapi/linux/sched.h>

#include <linux/sched/prio.h>

#include <linux/capability.h>
#include <linux/mutex.h>
#include <linux/plist.h>
#include <linux/mm_types.h>
#include <asm/ptrace.h>

#include <linux/sem.h>
#include <linux/shm.h>
#include <linux/signal.h>
#include <linux/signal_types.h>
#include <linux/pid.h>
#include <linux/seccomp.h>
#include <linux/rculist.h>
#include <linux/rtmutex.h>

#include <linux/resource.h>
#include <linux/hrtimer.h>
#include <linux/kcov.h>
#include <linux/task_io_accounting.h>
#include <linux/latencytop.h>
#include <linux/cred.h>
#include <linux/gfp.h>
#include <linux/topology.h>
#include <linux/magic.h>
#include <linux/cgroup-defs.h>

#include <asm/current.h>

/* task_struct member predeclarations: */
struct audit_context;
struct autogroup;
struct backing_dev_info;
struct bio_list;
struct blk_plug;
struct cfs_rq;
struct filename;
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 sched_attr;
struct sched_param;
struct seq_file;
struct sighand_struct;
struct signal_struct;
struct task_delay_info;
struct task_group;
struct task_struct;
struct uts_namespace;

/*
 * 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.
 */
#define TASK_RUNNING            0
#define TASK_INTERRUPTIBLE      1
#define TASK_UNINTERRUPTIBLE    2
#define __TASK_STOPPED          4
#define __TASK_TRACED           8
/* in tsk->exit_state */
#define EXIT_DEAD               16
#define EXIT_ZOMBIE             32
#define EXIT_TRACE              (EXIT_ZOMBIE | EXIT_DEAD)
/* in tsk->state again */
#define TASK_DEAD               64
#define TASK_WAKEKILL           128
#define TASK_WAKING             256
#define TASK_PARKED             512
#define TASK_NOLOAD             1024
#define TASK_NEW                2048
#define TASK_STATE_MAX          4096

#define TASK_STATE_TO_CHAR_STR "RSDTtXZxKWPNn"

/* 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)
#define TASK_ALL                (TASK_NORMAL | __TASK_STOPPED | __TASK_TRACED)

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

#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

#define __set_current_state(state_value)                        \
        do {                                                    \
                current->task_state_change = _THIS_IP_;         \
                current->state = (state_value);                 \
        } while (0)
#define set_current_state(state_value)                          \
        do {                                                    \
                current->task_state_change = _THIS_IP_;         \
                smp_store_mb(current->state, (state_value));    \
        } 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() (and all other wakeup primitives) imply enough
 * barriers to order the store of the variable against wakeup.
 *
 * 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).
 *
 * This is obviously fine, since they both store the exact same value.
 *
 * Also see the comments of try_to_wake_up().
 */
#define __set_current_state(state_value)                \
        do { current->state = (state_value); } while (0)
#define set_current_state(state_value)                  \
        smp_store_mb(current->state, (state_value))

#endif

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

extern void sched_init(void);
extern void sched_init_smp(void);

extern cpumask_var_t cpu_isolated_map;

extern int runqueue_is_locked(int cpu);

extern void cpu_init (void);
extern void trap_init(void);
extern void update_process_times(int user);
extern void scheduler_tick(void);

#define MAX_SCHEDULE_TIMEOUT    LONG_MAX
extern signed long schedule_timeout(signed long timeout);
extern signed long schedule_timeout_interruptible(signed long timeout);
extern signed long schedule_timeout_killable(signed long timeout);
extern signed long schedule_timeout_uninterruptible(signed long timeout);
extern signed long schedule_timeout_idle(signed 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 - snaphsot 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
};

static inline void prev_cputime_init(struct prev_cputime *prev)
{
#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
        prev->utime = prev->stime = 0;
        raw_spin_lock_init(&prev->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 to cache expirations. */
#define virt_exp        utime
#define prof_exp        stime
#define sched_exp       sum_exec_runtime

/*
 * This is the atomic variant of task_cputime, which can be used for
 * storing and updating task_cputime statistics without locking.
 */
struct task_cputime_atomic {
        atomic64_t utime;
        atomic64_t stime;
        atomic64_t sum_exec_runtime;
};

#define INIT_CPUTIME_ATOMIC \
        (struct task_cputime_atomic) {                          \
                .utime = ATOMIC64_INIT(0),                      \
                .stime = ATOMIC64_INIT(0),                      \
                .sum_exec_runtime = ATOMIC64_INIT(0),           \
        }

#define PREEMPT_DISABLED        (PREEMPT_DISABLE_OFFSET + PREEMPT_ENABLED)

/*
 * Disable preemption until the scheduler is running -- use an unconditional
 * value so that it also works on !PREEMPT_COUNT kernels.
 *
 * Reset by start_kernel()->sched_init()->init_idle()->init_idle_preempt_count().
 */
#define INIT_PREEMPT_COUNT      PREEMPT_OFFSET

/*
 * Initial preempt_count value; reflects the preempt_count schedule invariant
 * which states that during context switches:
 *
 *    preempt_count() == 2*PREEMPT_DISABLE_OFFSET
 *
 * Note: PREEMPT_DISABLE_OFFSET is 0 for !PREEMPT_COUNT kernels.
 * Note: See finish_task_switch().
 */
#define FORK_PREEMPT_COUNT      (2*PREEMPT_DISABLE_OFFSET + PREEMPT_ENABLED)

/**
 * struct thread_group_cputimer - thread group interval timer counts
 * @cputime_atomic:     atomic thread group interval timers.
 * @running:            true when there are timers running and
 *                      @cputime_atomic receives updates.
 * @checking_timer:     true when a thread in the group is in the
 *                      process of checking for thread group timers.
 *
 * This structure contains the version of task_cputime, above, that is
 * used for thread group CPU timer calculations.
 */
struct thread_group_cputimer {
        struct task_cputime_atomic cputime_atomic;
        bool running;
        bool checking_timer;
};

#include <linux/rwsem.h>

#ifdef CONFIG_SCHED_INFO
struct sched_info {
        /* cumulative counters */
        unsigned long pcount;         /* # of times run on this cpu */
        unsigned long long run_delay; /* time spent waiting on a runqueue */

        /* timestamps */
        unsigned long long last_arrival,/* when we last ran on a cpu */
                           last_queued; /* when we were last queued to run */
};
#endif /* CONFIG_SCHED_INFO */

static inline int sched_info_on(void)
{
#ifdef CONFIG_SCHEDSTATS
        return 1;
#elif defined(CONFIG_TASK_DELAY_ACCT)
        extern int delayacct_on;
        return delayacct_on;
#else
        return 0;
#endif
}

#ifdef CONFIG_SCHEDSTATS
void force_schedstat_enabled(void);
#endif

/*
 * 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)

#ifdef ARCH_HAS_PREFETCH_SWITCH_STACK
extern void prefetch_stack(struct task_struct *t);
#else
static inline void prefetch_stack(struct task_struct *t) { }
#endif

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

/*
 * 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.
 *
 * load_avg may also take frequency scaling into account:
 *
 *   load_avg = runnable% * scale_load_down(load) * freq%
 *
 * where freq% is the CPU frequency normalized to the highest frequency.
 *
 * [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.
 *
 * util_avg may also factor frequency scaling and CPU capacity scaling:
 *
 *   util_avg = running% * SCHED_CAPACITY_SCALE * freq% * capacity%
 *
 * where freq% is the same as above, and capacity% is the CPU capacity
 * normalized to the greatest capacity (due to uarch differences, etc).
 *
 * N.B., the above ratios (runnable%, running%, freq%, and capacity%)
 * 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, load_sum;
        u32 util_sum, period_contrib;
        unsigned long load_avg, util_avg;
};

#ifdef CONFIG_SCHEDSTATS
struct sched_statistics {
        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 {
        struct load_weight      load;           /* for load-balancing */
        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;

#ifdef CONFIG_SCHEDSTATS
        struct sched_statistics statistics;
#endif

#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 ____cacheline_aligned_in_smp;
#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
};

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_deadline             */

        /*
         * Actual scheduling parameters. Initialized with the values above,
         * they are continously 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.
         */
        int dl_throttled, dl_boosted, dl_yielded;

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

union rcu_special {
        struct {
                u8 blocked;
                u8 need_qs;
                u8 exp_need_qs;
                u8 pad; /* Otherwise the compiler can store garbage here. */
        } 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;
};

/* Track pages that require TLB flushes */
struct tlbflush_unmap_batch {
        /*
         * Each bit set is a CPU that potentially has a TLB entry for one of
         * the PFNs being flushed. See set_tlb_ubc_flush_pending().
         */
        struct cpumask cpumask;

        /* True if any bit in cpumask is set */
        bool flush_required;

        /*
         * If true then the PTE was dirty when unmapped. The entry must be
         * flushed before IO is initiated or a stale TLB entry potentially
         * allows an update without redirtying the page.
         */
        bool writable;
};

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
        volatile long state;    /* -1 unrunnable, 0 runnable, >0 stopped */
        void *stack;
        atomic_t usage;
        unsigned int flags;     /* per process flags, defined below */
        unsigned int ptrace;

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

        int wake_cpu;
#endif
        int on_rq;

        int prio, static_prio, 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_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;
        cpumask_t cpus_allowed;

#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;
        bool rcu_tasks_holdout;
        struct list_head rcu_tasks_holdout_list;
        int rcu_tasks_idle_cpu;
#endif /* #ifdef CONFIG_TASKS_RCU */

#ifdef CONFIG_SCHED_INFO
        struct sched_info sched_info;
#endif

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

        struct mm_struct *mm, *active_mm;

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

#if defined(SPLIT_RSS_COUNTING)
        struct task_rss_stat    rss_stat;
#endif
/* task state */
        int exit_state;
        int exit_code, exit_signal;
        int pdeath_signal;  /*  The signal sent when the parent dies  */
        unsigned long jobctl;   /* JOBCTL_*, siglock protected */

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

        /* unserialized, strictly 'current' */
        unsigned in_execve:1; /* bit to tell LSMs we're in execve */
        unsigned in_iowait:1;
#if !defined(TIF_RESTORE_SIGMASK)
        unsigned restore_sigmask:1;
#endif
#ifdef CONFIG_MEMCG
        unsigned memcg_may_oom:1;
#ifndef CONFIG_SLOB
        unsigned memcg_kmem_skip_account:1;
#endif
#endif
#ifdef CONFIG_COMPAT_BRK
        unsigned brk_randomized:1;
#endif

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

        struct restart_block restart_block;

        pid_t pid;
        pid_t tgid;

#ifdef CONFIG_CC_STACKPROTECTOR
        /* Canary value for the -fstack-protector gcc feature */
        unsigned long stack_canary;
#endif
        /*
         * pointers to (original) parent process, youngest child, younger sibling,
         * older sibling, respectively.  (p->father can be replaced with
         * p->real_parent->pid)
         */
        struct task_struct __rcu *real_parent; /* real parent process */
        struct task_struct __rcu *parent; /* recipient of SIGCHLD, wait4() reports */
        /*
         * children/sibling forms the list of my natural children
         */
        struct list_head children;      /* list of my children */
        struct list_head sibling;       /* linkage in my parent's children list */
        struct task_struct *group_leader;       /* threadgroup leader */

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

        /* PID/PID hash table linkage. */
        struct pid_link pids[PIDTYPE_MAX];
        struct list_head thread_group;
        struct list_head thread_node;

        struct completion *vfork_done;          /* for vfork() */
        int __user *set_child_tid;              /* CLONE_CHILD_SETTID */
        int __user *clear_child_tid;            /* CLONE_CHILD_CLEARTID */

        u64 utime, stime;
#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
        u64 utimescaled, stimescaled;
#endif
        u64 gtime;
        struct prev_cputime prev_cputime;
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
        seqcount_t vtime_seqcount;
        unsigned long long vtime_snap;
        enum {
                /* 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,
        } vtime_snap_whence;
#endif

#ifdef CONFIG_NO_HZ_FULL
        atomic_t tick_dep_mask;
#endif
        unsigned long nvcsw, nivcsw; /* context switch counts */
        u64 start_time;         /* monotonic time in nsec */
        u64 real_start_time;    /* boot based time in nsec */
/* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
        unsigned long min_flt, maj_flt;

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

/* process credentials */
        const struct cred __rcu *ptracer_cred; /* Tracer's credentials at attach */
        const struct cred __rcu *real_cred; /* objective and real subjective task
                                         * credentials (COW) */
        const struct cred __rcu *cred;  /* effective (overridable) subjective task
                                         * credentials (COW) */
        char comm[TASK_COMM_LEN]; /* executable name excluding path
                                     - access with [gs]et_task_comm (which lock
                                       it with task_lock())
                                     - initialized normally by setup_new_exec */
/* file system info */
        struct nameidata *nameidata;
#ifdef CONFIG_SYSVIPC
/* ipc stuff */
        struct sysv_sem sysvsem;
        struct sysv_shm sysvshm;
#endif
#ifdef CONFIG_DETECT_HUNG_TASK
/* hung task detection */
        unsigned long last_switch_count;
#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, real_blocked;
        sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */
        struct sigpending pending;

        unsigned long sas_ss_sp;
        size_t sas_ss_size;
        unsigned sas_ss_flags;

        struct callback_head *task_works;

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

/* Thread group tracking */
        u32 parent_exec_id;
        u32 self_exec_id;
/* Protection of (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 pi_waiters;
        struct rb_node *pi_waiters_leftmost;
        /* 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_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];
        gfp_t lockdep_reclaim_gfp;
#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;

        unsigned long ptrace_message;
        siginfo_t *last_siginfo; /* For ptrace use.  */
        struct task_io_accounting ioac;
#if defined(CONFIG_TASK_XACCT)
        u64 acct_rss_mem1;      /* accumulated rss usage */
        u64 acct_vm_mem1;       /* accumulated virtual memory usage */
        u64 acct_timexpd;       /* stime + utime since last update */
#endif
#ifdef CONFIG_CPUSETS
        nodemask_t mems_allowed;        /* Protected by alloc_lock */
        seqcount_t mems_allowed_seq;    /* Seqence no to catch updates */
        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_INTEL_RDT_A
        int closid;
#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
        struct mempolicy *mempolicy;    /* Protected by alloc_lock */
        short il_next;
        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;
        u64 node_stamp;                 /* migration stamp  */
        u64 last_task_numa_placement;
        u64 last_sum_exec_runtime;
        struct callback_head numa_work;

        struct list_head numa_entry;
        struct numa_group *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_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
        struct tlbflush_unmap_batch tlb_ubc;
#endif

        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;
#endif
        /*
         * when (nr_dirtied >= nr_dirtied_pause), it's time to call
         * balance_dirty_pages() for some dirty throttling pause
         */
        int nr_dirtied;
        int nr_dirtied_pause;
        unsigned long dirty_paused_when; /* start of a write-and-pause period */

#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;
        /* Stack of return addresses for return function tracing */
        struct ftrace_ret_stack *ret_stack;
        /* time stamp 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 for the 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). */
        enum kcov_mode kcov_mode;
        /* Size of the kcov_area. */
        unsigned        kcov_size;
        /* Buffer for coverage collection. */
        void            *kcov_area;
        /* kcov desciptor 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;
#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. */
        atomic_t stack_refcount;
#endif
/* 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->pids[PIDTYPE_PID].pid;
}

static inline struct pid *task_tgid(struct task_struct *task)
{
        return task->group_leader->pids[PIDTYPE_PID].pid;
}

/*
 * Without tasklist or rcu lock it is not safe to dereference
 * the result of task_pgrp/task_session even if task == current,
 * we can race with another thread doing sys_setsid/sys_setpgid.
 */
static inline struct pid *task_pgrp(struct task_struct *task)
{
        return task->group_leader->pids[PIDTYPE_PGID].pid;
}

static inline struct pid *task_session(struct task_struct *task)
{
        return task->group_leader->pids[PIDTYPE_SID].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;
 *
 * set_task_vxid()   : assigns a virtual id to a task;
 *
 * 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_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);

static inline pid_t task_tgid_vnr(struct task_struct *tsk)
{
        return pid_vnr(task_tgid(tsk));
}


static inline int pid_alive(const struct task_struct *p);
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);
}

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);
}

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

/**
 * 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->pids[PIDTYPE_PID].pid != NULL;
}

/**
 * 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;

extern void free_task(struct task_struct *tsk);
#define get_task_struct(tsk) do { atomic_inc(&(tsk)->usage); } while(0)

extern void __put_task_struct(struct task_struct *t);

static inline void put_task_struct(struct task_struct *t)
{
        if (atomic_dec_and_test(&t->usage))
                __put_task_struct(t);
}

struct task_struct *task_rcu_dereference(struct task_struct **ptask);
struct task_struct *try_get_task_struct(struct task_struct **ptask);

#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
extern void task_cputime(struct task_struct *t,
                         u64 *utime, u64 *stime);
extern u64 task_gtime(struct task_struct *t);
#else
static inline void task_cputime(struct task_struct *t,
                                u64 *utime, u64 *stime)
{
        *utime = t->utime;
        *stime = t->stime;
}

static inline u64 task_gtime(struct task_struct *t)
{
        return t->gtime;
}
#endif

#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
static inline void task_cputime_scaled(struct task_struct *t,
                                       u64 *utimescaled,
                                       u64 *stimescaled)
{
        *utimescaled = t->utimescaled;
        *stimescaled = t->stimescaled;
}
#else
static inline void task_cputime_scaled(struct task_struct *t,
                                       u64 *utimescaled,
                                       u64 *stimescaled)
{
        task_cputime(t, utimescaled, stimescaled);
}
#endif

extern void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st);
extern void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st);

/*
 * 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_FSTRANS      0x00020000      /* inside a filesystem transaction */
#define PF_KSWAPD       0x00040000      /* I am kswapd */
#define PF_MEMALLOC_NOIO 0x00080000     /* Allocating memory without IO involved */
#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_NO_SETAFFINITY 0x04000000    /* Userland is not allowed to meddle with cpus_allowed */
#define PF_MCE_EARLY    0x08000000      /* Early kill for mce process policy */
#define PF_MUTEX_TESTER 0x20000000      /* Thread belongs to the rt mutex tester */
#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)

/* 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_LMK_WAITING  3      /* Lowmemorykiller is waiting */


#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(LMK_WAITING, lmk_waiting)
TASK_PFA_SET(LMK_WAITING, lmk_waiting)

static inline void tsk_restore_flags(struct task_struct *task,
                                unsigned long orig_flags, unsigned long flags)
{
        task->flags &= ~flags;
        task->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

#ifndef cpu_relax_yield
#define cpu_relax_yield() cpu_relax()
#endif

extern unsigned long long
task_sched_runtime(struct task_struct *task);

/* sched_exec is called by processes performing an exec */
#ifdef CONFIG_SMP
extern void sched_exec(void);
#else
#define sched_exec()   {}
#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 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 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_THREAD_INFO_IN_TASK
        struct thread_info thread_info;
#endif
        unsigned long stack[THREAD_SIZE/sizeof(long)];
};

#ifndef __HAVE_ARCH_KSTACK_END
static inline int kstack_end(void *addr)
{
        /* Reliable end of stack detection:
         * Some APM bios versions misalign the stack
         */
        return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
}
#endif

extern union thread_union init_thread_union;
extern struct task_struct init_task;

extern struct pid_namespace init_pid_ns;

/*
 * 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);

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 exit_files(struct task_struct *);

extern void exit_itimers(struct signal_struct *);

extern int do_execve(struct filename *,
                     const char __user * const __user *,
                     const char __user * const __user *);
extern int do_execveat(int, struct filename *,
                       const char __user * const __user *,
                       const char __user * const __user *,
                       int);

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, struct task_struct *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

/*
 * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
 * subscriptions and synchronises with wait4().  Also used in procfs.  Also
 * pins the final release of task.io_context.  Also protects ->cpuset and
 * ->cgroup.subsys[]. And ->vfork_done.
 *
 * Nests both inside and outside of read_lock(&tasklist_lock).
 * It must not be nested with write_lock_irq(&tasklist_lock),
 * neither inside nor outside.
 */
static inline void task_lock(struct task_struct *p)
{
        spin_lock(&p->alloc_lock);
}

static inline void task_unlock(struct task_struct *p)
{
        spin_unlock(&p->alloc_lock);
}

#ifdef CONFIG_THREAD_INFO_IN_TASK

static inline struct thread_info *task_thread_info(struct task_struct *task)
{
        return &task->thread_info;
}

/*
 * When accessing the stack of a non-current task that might exit, use
 * try_get_task_stack() instead.  task_stack_page will return a pointer
 * that could get freed out from under you.
 */
static inline void *task_stack_page(const struct task_struct *task)
{
        return task->stack;
}

#define setup_thread_stack(new,old)     do { } while(0)

static inline unsigned long *end_of_stack(const struct task_struct *task)
{
        return task->stack;
}

#elif !defined(__HAVE_THREAD_FUNCTIONS)

#define task_thread_info(task)  ((struct thread_info *)(task)->stack)
#define task_stack_page(task)   ((void *)(task)->stack)

static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
{
        *task_thread_info(p) = *task_thread_info(org);
        task_thread_info(p)->task = p;
}

/*
 * Return the address of the last usable long on the stack.
 *
 * When the stack grows down, this is just above the thread
 * info struct. Going any lower will corrupt the threadinfo.
 *
 * When the stack grows up, this is the highest address.
 * Beyond that position, we corrupt data on the next page.
 */
static inline unsigned long *end_of_stack(struct task_struct *p)
{
#ifdef CONFIG_STACK_GROWSUP
        return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
#else
        return (unsigned long *)(task_thread_info(p) + 1);
#endif
}

#endif

#ifdef CONFIG_THREAD_INFO_IN_TASK
static inline void *try_get_task_stack(struct task_struct *tsk)
{
        return atomic_inc_not_zero(&tsk->stack_refcount) ?
                task_stack_page(tsk) : NULL;
}

extern void put_task_stack(struct task_struct *tsk);
#else
static inline void *try_get_task_stack(struct task_struct *tsk)
{
        return task_stack_page(tsk);
}

static inline void put_task_stack(struct task_struct *tsk) {}
#endif

#define task_stack_end_corrupted(task) \
                (*(end_of_stack(task)) != STACK_END_MAGIC)

static inline int object_is_on_stack(void *obj)
{
        void *stack = task_stack_page(current);

        return (obj >= stack) && (obj < (stack + THREAD_SIZE));
}

extern void thread_stack_cache_init(void);

#ifdef CONFIG_DEBUG_STACK_USAGE
static inline unsigned long stack_not_used(struct task_struct *p)
{
        unsigned long *n = end_of_stack(p);

        do {    /* Skip over canary */
# ifdef CONFIG_STACK_GROWSUP
                n--;
# else
                n++;
# endif
        } while (!*n);

# ifdef CONFIG_STACK_GROWSUP
        return (unsigned long)end_of_stack(p) - (unsigned long)n;
# else
        return (unsigned long)n - (unsigned long)end_of_stack(p);
# endif
}
#endif
extern void set_task_stack_end_magic(struct task_struct *tsk);

/* 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 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,
 * cond_resched_softirq() will enable bhs 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);                              \
})

extern int __cond_resched_softirq(void);

#define cond_resched_softirq() ({                                       \
        ___might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET);     \
        __cond_resched_softirq();                                       \
})

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());
}

/*
 * Thread group CPU time accounting.
 */
void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times);

/*
 * 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 p->cpu;
#else
        return task_thread_info(p)->cpu;
#endif
}

static inline int task_node(const struct task_struct *p)
{
        return cpu_to_node(task_cpu(p));
}

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);

#ifdef CONFIG_CGROUP_SCHED
extern struct task_group root_task_group;
#endif /* CONFIG_CGROUP_SCHED */

extern int task_can_switch_user(struct user_struct *up,
                                        struct task_struct *tsk);

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

#endif