kernel_task_struct.c

  struct task_struct {
      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;
  #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

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

      /*
       * fpu_counter contains the number of consecutive context switches
       * that the FPU is used. If this is over a threshold, the lazy fpu
       * saving becomes unlazy to save the trap. This is an unsigned char
       * so that after 256 times the counter wraps and the behavior turns
       * lazy again; this to deal with bursty apps that only use FPU for
       * a short time
       */
      unsigned char fpu_counter;
  #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;
      char rcu_read_unlock_special;
      struct list_head rcu_node_entry;
  #endif /* #ifdef CONFIG_PREEMPT_RCU */
  #ifdef CONFIG_TREE_PREEMPT_RCU
      struct rcu_node *rcu_blocked_node;
  #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
  #ifdef CONFIG_RCU_BOOST
      struct rt_mutex *rcu_boost_mutex;
  #endif /* #ifdef CONFIG_RCU_BOOST */

  #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
      struct sched_info sched_info;
  #endif

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

      struct mm_struct *mm, *active_mm;
  #ifdef CONFIG_COMPAT_BRK
      unsigned brk_randomized:1;
  #endif
  #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 int jobctl;    /* JOBCTL_*, siglock protected */
      /* ??? */
      unsigned int personality;
      unsigned did_exec:1;
      unsigned in_execve:1;   /* Tell the LSMs that the process is doing an
                   * execve */
      unsigned in_iowait:1;

      /* task may not gain privileges */
      unsigned no_new_privs:1;

      /* Revert to default priority/policy when forking */
      unsigned sched_reset_on_fork:1;
      unsigned sched_contributes_to_load:1;

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

      cputime_t utime, stime, utimescaled, stimescaled;
      cputime_t gtime;
  #ifndef CONFIG_VIRT_CPU_ACCOUNTING
      cputime_t prev_utime, prev_stime;
  #endif
      unsigned long nvcsw, nivcsw; /* context switch counts */
      struct timespec start_time;         /* monotonic time */
      struct timespec real_start_time;    /* boot based time */
  /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
      unsigned long min_flt, maj_flt;

      struct task_cputime cputime_expires;
      struct list_head cpu_timers[3];

  /* process credentials */
      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 */
      int link_count, total_link_count;
  #ifdef CONFIG_SYSVIPC
  /* ipc stuff */
      struct sysv_sem sysvsem;
  #endif
  #ifdef CONFIG_DETECT_HUNG_TASK
  /* hung task detection */
      unsigned long last_switch_count;
  #endif
  /* CPU-specific state of this task */
      struct thread_struct thread;
  /* 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;
      int (*notifier)(void *priv);
      void *notifier_data;
      sigset_t *notifier_mask;
      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;

  #ifdef CONFIG_RT_MUTEXES
      /* PI waiters blocked on a rt_mutex held by this task */
      struct plist_head pi_waiters;
      /* 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

  /* 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 */
      cputime_t 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_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_NUMA
      struct mempolicy *mempolicy;    /* Protected by alloc_lock */
      short il_next;
      short pref_node_fork;
  #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.
       */
      unsigned long timer_slack_ns;
      unsigned long default_timer_slack_ns;

  #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_MEMCG /* memcg uses this to do batch job */
      struct memcg_batch_info {
          int do_batch;   /* incremented when batch uncharge started */
          struct mem_cgroup *memcg; /* target memcg of uncharge */
          unsigned long nr_pages; /* uncharged usage */
          unsigned long memsw_nr_pages; /* uncharged mem+swap usage */
      } memcg_batch;
  #endif
  #ifdef CONFIG_HAVE_HW_BREAKPOINT
      atomic_t ptrace_bp_refcnt;
  #endif
  #ifdef CONFIG_UPROBES
      struct uprobe_task *utask;
  #endif
  };