struct task_struct {
volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */ // 进程状态
void *stack; // 内存指针
atomic_t usage; //
unsigned int flags; /* per process flags, defined below */ // 进程标号 （进程名字）
unsigned int ptrace;
int lock_depth; /* BKL lock depth */ // BLK 锁深度
#ifdef CONFIG_SMP
#ifdef __ARCH_WANT_UNLOCKED_CTXSW // 配置多核多线程
int oncpu;
#endif
#endif
int prio, static_prio, normal_prio; // 进程的优先级
unsigned int rt_priority; // 实时进程的优先级
const struct sched_class *sched_class; // 调度器的指针
struct sched_entity se; // 调度器 实例化的对象
struct sched_rt_entity rt; // 实时 调度器的一个对象
#ifdef CONFIG_PREEMPT_NOTIFIERS // 配置 抢占通知器
/* list of struct preempt_notifier: */
struct hlist_head preempt_notifiers;
#endif
/*
* fpu_counter contains the number of consecutive context switches // fpu_count 里面内容是如果一个浮点运算器被使用，它
* that the FPU is used. If this is over a threshold, the lazy fpu // 记录着连续的上下文切换的次数，如果fpu_Count超过一个
* saving becomes unlazy to save the trap. This is an unsigned char // 临界值，不怎么工作的FPU会火力全开以至于当fpu_count
* so that after 256 times the counter wraps and the behavior turns // 超过 256次后才变得闲置下来，为了解决这个问题，FPU
* lazy again; this to deal with bursty apps that only use FPU for // 仅仅使用一段时间
* a short time
*/
unsigned char fpu_counter; // 定义 fpu_count
#ifdef CONFIG_BLK_DEV_IO_TRACE // 配置 BLK 锁开发版的输入输出跟踪器
unsigned int btrace_seq;
#endif
unsigned int policy;
cpumask_t cpus_allowed;
#ifdef CONFIG_TREE_PREEMPT_RCU // 配置 抢占树，抢占的结构体的读写机制，即RCU 机制。
int rcu_read_lock_nesting;
char rcu_read_unlock_special;
struct rcu_node *rcu_blocked_node;
struct list_head rcu_node_entry;
#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
struct sched_info sched_info; // 调度器 的 状态
#endif
struct list_head tasks;
struct plist_node pushable_tasks;
struct mm_struct *mm, *active_mm; // 虚拟地址空间的结构体
/* task state */ // 进程退出时getpid 就获取status就是它。
int exit_state; // task 状态 ，正常退出状态
int exit_code, exit_signal; // 退出信号
int pdeath_signal; /* The signal sent when the parent dies */ // 当成为孤儿进程时发送信号
/* ??? */
unsigned int personality; // 这个字段表明了 进程的状态
unsigned did_exec:1;
unsigned in_execve:1; /* Tell the LSMs that the process is doing an
* execve */ 定义 四个字段 来告诉Linux安全模块进程的状态
// 第一个表已经调过了exec族函数，已经发生了进程的程序替换 第二个代表该进程正在调用execve函数 第三个 正在等待i/o设备 第四个 表示当fork生成子进程时，是否恢复了进程的默认优先级
unsigned in_iowait:1;
/* Revert to default priority/policy when forking */
unsigned sched_reset_on_fork:1;
pid_t pid;
pid_t tgid;
#ifdef CONFIG_CC_STACKPROTECTOR // 配置堆栈保护措施
/* Canary value for the -fstack-protector gcc feature */
unsigned long stack_canary; // canary值 保护编译器 防止堆栈溢出 导致的返回地址被填充
#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 *real_parent; /* real parent process */
struct task_struct *parent; /* recipient of SIGCHLD, wait4() reports */
/*
* children/sibling forms the list of my natural children
*/
struct list_head children; /* list of my children */ // 子节点 和 兄弟节点的定义
struct list_head sibling; /* linkage in my parent's children list */
struct task_struct *group_leader; /* threadgroup leader */ // 线程组的头结点
/*
* 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; // 跟踪器的头结点 ， 跟踪器 跟踪 进程的逻辑流，即PC指令流
struct list_head ptrace_entry;
/* PID/PID hash table linkage. */
struct pid_link pids[PIDTYPE_MAX]; // 定义 PID_LINK 结构体 用它通过PID在哈希散列表中查找相应的task_struct
struct list_head thread_group; // 用来保存线程组的PID
struct completion *vfork_done; /* for vfork() */
int __user *set_child_tid; /* CLONE_CHILD_SETTID */ // 指向 用户创造创立的线程的TID 号
int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */ // 指向被清除的线程的TID号
cputime_t utime, stime, utimescaled, stimescaled;
cputime_t gtime;
cputime_t prev_utime, prev_stime;
unsigned long nvcsw, nivcsw; /* context switch counts */ // 上下文切换的次数
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 *real_cred; /* objective and real subjective task
* credentials (COW) */
const struct cred *cred; /* effective (overridable) subjective task
* credentials (COW) */
struct mutex cred_guard_mutex; /* guard against foreign influences on
* credential calculations
* (notably. ptrace) */
struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */
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 */ // 文件系统信息
int link_count, total_link_count;
#ifdef CONFIG_SYSVIPC // 配置进程的通信机制
/* 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; // CPU特殊 状态的测试 , 线程结构体
/* filesystem information */
struct fs_struct *fs; //fs 指向一个文件系统信息结构体 ,该结构体有文件系统的信息
/* open file information */ // 指向记录打开文件信息的 结构体
struct files_struct *files;
/* namespaces */ // 命名空间的定义
struct nsproxy *nsproxy;
/* signal handlers */ // 配置 进程的信号处理
struct signal_struct *signal; // 以下是普通信号部分
struct sighand_struct *sighand; //这个指向 handler表
sigset_t blocked, real_blocked; // 这个表示进程的屏蔽字
sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */ 这个用来储存之前的屏蔽字，在调用sigprocmask时。
struct sigpending pending; // pending表
unsigned long sas_ss_sp; // 以下是实时信号部分
size_t sas_ss_size;
int (*notifier)(void *priv);
void *notifier_data;
sigset_t *notifier_mask;
struct audit_context *audit_context;
#ifdef CONFIG_AUDITSYSCALL // 配置系统调用
uid_t loginuid;
unsigned int sessionid;
#endif
seccomp_t seccomp;
#ifdef CONFIG_UTRACE
struct utrace *utrace;
unsigned long utrace_flags;
#endif
/* Thread group tracking */
u32 parent_exec_id;
u32 self_exec_id;
/* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed,
* mempolicy */ 配置器保护措施配置
spinlock_t alloc_lock;
#ifdef CONFIG_GENERIC_HARDIRQS
/* IRQ handler threads */
struct irqaction *irqaction;
#endif
/* Protection of the PI data structures: */
spinlock_t pi_lock;
#ifdef CONFIG_RT_MUTEXES // 互斥的配置
/* 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;
int hardirqs_enabled;
unsigned long hardirq_enable_ip;
unsigned int hardirq_enable_event;
unsigned long hardirq_disable_ip;
unsigned int hardirq_disable_event;
int softirqs_enabled;
unsigned long softirq_disable_ip;
unsigned int softirq_disable_event;
unsigned long softirq_enable_ip;
unsigned int softirq_enable_event;
int hardirq_context;
int softirq_context;
#endif
#ifdef CONFIG_LOCKDEP // 死锁模块的配置
# 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 */ // 文件系统的日志信息
void *journal_info;
/* stacked block device info */
struct bio *bio_list, **bio_tail;
/* VM state */ //VM 虚拟机的状态
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 */ // 定义一个结构体 标志 内存是否允许访问 保护配置器的锁的
#ifndef __GENKSYMS__
/*
* This does not change the size of the struct_task(2+2+4=4+4)
* so the offsets of the remaining fields are unchanged and
* therefore the kABI is preserved. Only the kernel uses
* cpuset_mem_spread_rotor and cpuset_slab_spread_rotor so
* it is safe to change it to use shorts instead of ints.
*/
unsigned short cpuset_mem_spread_rotor;
unsigned short cpuset_slab_spread_rotor;
int mems_allowed_change_disable;
#else
int cpuset_mem_spread_rotor;
int cpuset_slab_spread_rotor;
#endif
#endif
#ifdef CONFIG_CGROUPS // 配置控制组信息
/* Control Group info protected by css_set_lock */
struct css_set *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
#ifndef __GENKSYMS__
void * __reserved_perf__;
#else
struct perf_event_context *perf_event_ctxp;
#endif
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;
#endif
atomic_t fs_excl; /* holding fs exclusive resources */
struct rcu_head rcu;
/*
* cache last used pipe for splice
*/
struct pipe_inode_info *splice_pipe;
#ifdef CONFIG_TASK_DELAY_ACCT
struct task_delay_info *delays;
#endif
#ifdef CONFIG_FAULT_INJECTION
int make_it_fail;
#endif
struct prop_local_single dirties;
#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;
struct list_head *scm_work_list;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/* Index of current stored adress 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; // 超越跟踪器的跟踪深度的函数数量。
/* Pause for the tracing */
atomic_t tracing_graph_pause;
#endif
#ifdef CONFIG_TRACING //配置 跟踪器
/* state flags for use by tracers */
unsigned long trace;
/* bitmask of trace recursion */
unsigned long trace_recursion;
#endif /* CONFIG_TRACING */
/* reserved for Red Hat */
unsigned long rh_reserved[2];
#ifndef __GENKSYMS__
struct perf_event_context *perf_event_ctxp[perf_nr_task_contexts];
#ifdef CONFIG_CGROUP_MEM_RES_CTLR /* 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 bytes; /* uncharged usage */
unsigned long memsw_bytes; /* uncharged mem+swap usage */
} memcg_batch;
#endif
#endif
};
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