Linux下的进程控制块——task_struct

在Linux中具体实现PCB的是 task_struct数据结构，以下实现摘自github

我想说它真的很长很长...... ↓

 struct task_struct {
     volatile long state;    /* -1 unrunnable, 0 runnable, >0 stopped *ruxia/
     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;
     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 */
     u32 vmacache_seqnum;
     struct vm_area_struct *vmacache[VMACACHE_SIZE];
 #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:;
     unsigned sched_contributes_to_load:;
     unsigned sched_migrated:;
     unsigned sched_remote_wakeup:;
     unsigned :; /* force alignment to the next boundary */

     /* unserialized, strictly 'current' */
     unsigned in_execve:; /* bit to tell LSMs we're in execve */
     unsigned in_iowait:;
 #ifdef CONFIG_MEMCG
     unsigned memcg_may_oom:;
 #ifndef CONFIG_SLOB
     unsigned memcg_kmem_skip_account:;
 #endif
 #endif
 #ifdef CONFIG_COMPAT_BRK
     unsigned brk_randomized:;
 #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 */

     cputime_t utime, stime, utimescaled, stimescaled;
     cputime_t 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 = ,
         /* 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;

     struct task_cputime cputime_expires;
     struct list_head cpu_timers[];

 /* 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 */
     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 */
     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_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[];

     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
 /* 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!
  */
 };