文章目錄

• 一、task_struct 結構體
• 二、task_struct 結構體代碼示例

一、task_struct 結構體

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在 Linux 操作系統 中 , 進程 作為 調度的實體 , 需要將其抽象為 " 進程控制塊 " , 英文全稱 " Progress Control Block " , 簡稱 PCB ;

在 Linux 內核 中 , " 進程控制塊 " 是通過 task_struct 結構體 進行描述的 ;

Linux 內核中 , 所有 進程管理 相關算法邏輯 , 都是基于 task_struct 結構體的 ;

task_struct 結構體在 linux-5.6.18\include\linux\sched.h 頭文件中定義 ,

第 $629$ ~ $1300$ 行就是 struct task_struct 結構體定義的代碼 ;

二、task_struct 結構體代碼示例

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struct task_struct { #ifdef CONFIG_THREAD_INFO_IN_TASK/** For reasons of header soup (see current_thread_info()), this* must be the first element of task_struct.*/struct thread_info thread_info; #endif/* -1 unrunnable, 0 runnable, >0 stopped: */volatile long state;/** This begins the randomizable portion of task_struct. Only* scheduling-critical items should be added above here.*/randomized_struct_fields_startvoid *stack;refcount_t usage;/* Per task flags (PF_*), defined further below: */unsigned int flags;unsigned int ptrace;#ifdef CONFIG_SMPstruct llist_node wake_entry;int on_cpu; #ifdef CONFIG_THREAD_INFO_IN_TASK/* Current CPU: */unsigned int cpu; #endifunsigned int wakee_flips;unsigned long wakee_flip_decay_ts;struct task_struct *last_wakee;/** recent_used_cpu is initially set as the last CPU used by a task* that wakes affine another task. Waker/wakee relationships can* push tasks around a CPU where each wakeup moves to the next one.* Tracking a recently used CPU allows a quick search for a recently* used CPU that may be idle.*/int recent_used_cpu;int wake_cpu; #endifint on_rq;int prio;int static_prio;int normal_prio;unsigned int rt_priority;const struct sched_class *sched_class;struct sched_entity se;struct sched_rt_entity rt; #ifdef CONFIG_CGROUP_SCHEDstruct task_group *sched_task_group; #endifstruct sched_dl_entity dl;#ifdef CONFIG_UCLAMP_TASK/* Clamp values requested for a scheduling entity */struct uclamp_se uclamp_req[UCLAMP_CNT];/* Effective clamp values used for a scheduling entity */struct uclamp_se uclamp[UCLAMP_CNT]; #endif#ifdef CONFIG_PREEMPT_NOTIFIERS/* List of struct preempt_notifier: */struct hlist_head preempt_notifiers; #endif#ifdef CONFIG_BLK_DEV_IO_TRACEunsigned int btrace_seq; #endifunsigned int policy;int nr_cpus_allowed;const cpumask_t *cpus_ptr;cpumask_t cpus_mask;#ifdef CONFIG_PREEMPT_RCUint 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_RCUunsigned long rcu_tasks_nvcsw;u8 rcu_tasks_holdout;u8 rcu_tasks_idx;int rcu_tasks_idle_cpu;struct list_head rcu_tasks_holdout_list; #endif /* #ifdef CONFIG_TASKS_RCU */struct sched_info sched_info;struct list_head tasks; #ifdef CONFIG_SMPstruct plist_node pushable_tasks;struct rb_node pushable_dl_tasks; #endifstruct mm_struct *mm;struct mm_struct *active_mm;/* Per-thread vma caching: */struct vmacache vmacache;#ifdef SPLIT_RSS_COUNTINGstruct task_rss_stat rss_stat; #endifint exit_state;int exit_code;int exit_signal;/* The signal sent when the parent dies: */int pdeath_signal;/* JOBCTL_*, siglock protected: */unsigned long jobctl;/* Used for emulating ABI behavior of previous Linux versions: */unsigned int personality;/* Scheduler bits, serialized by scheduler locks: */unsigned sched_reset_on_fork:1;unsigned sched_contributes_to_load:1;unsigned sched_migrated:1;unsigned sched_remote_wakeup:1; #ifdef CONFIG_PSIunsigned sched_psi_wake_requeue:1; #endif/* Force alignment to the next boundary: */unsigned :0;/* Unserialized, strictly 'current' *//* Bit to tell LSMs we're in execve(): */unsigned in_execve:1;unsigned in_iowait:1; #ifndef TIF_RESTORE_SIGMASKunsigned restore_sigmask:1; #endif #ifdef CONFIG_MEMCGunsigned in_user_fault:1; #endif #ifdef CONFIG_COMPAT_BRKunsigned brk_randomized:1; #endif #ifdef CONFIG_CGROUPS/* disallow userland-initiated cgroup migration */unsigned no_cgroup_migration:1;/* task is frozen/stopped (used by the cgroup freezer) */unsigned frozen:1; #endif #ifdef CONFIG_BLK_CGROUP/* to be used once the psi infrastructure lands upstream. */unsigned use_memdelay:1; #endifunsigned long atomic_flags; /* Flags requiring atomic access. */struct restart_block restart_block;pid_t pid;pid_t tgid;#ifdef CONFIG_STACKPROTECTOR/* Canary value for the -fstack-protector GCC feature: */unsigned long stack_canary; #endif/** Pointers to the (original) parent process, youngest child, younger sibling,* older sibling, respectively. (p->father can be replaced with* p->real_parent->pid)*//* Real parent process: */struct task_struct __rcu *real_parent;/* Recipient of SIGCHLD, wait4() reports: */struct task_struct __rcu *parent;/** Children/sibling form the list of natural children:*/struct list_head children;struct list_head sibling;struct task_struct *group_leader;/** 'ptraced' is the list of tasks this task is using ptrace() on.** This includes both natural children and PTRACE_ATTACH targets.* 'ptrace_entry' is this task's link on the p->parent->ptraced list.*/struct list_head ptraced;struct list_head ptrace_entry;/* PID/PID hash table linkage. */struct pid *thread_pid;struct hlist_node pid_links[PIDTYPE_MAX];struct list_head thread_group;struct list_head thread_node;struct completion *vfork_done;/* CLONE_CHILD_SETTID: */int __user *set_child_tid;/* CLONE_CHILD_CLEARTID: */int __user *clear_child_tid;u64 utime;u64 stime; #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIMEu64 utimescaled;u64 stimescaled; #endifu64 gtime;struct prev_cputime prev_cputime; #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GENstruct vtime vtime; #endif#ifdef CONFIG_NO_HZ_FULLatomic_t tick_dep_mask; #endif/* Context switch counts: */unsigned long nvcsw;unsigned long nivcsw;/* Monotonic time in nsecs: */u64 start_time;/* Boot based time in nsecs: */u64 start_boottime;/* MM fault and swap info: this can arguably be seen as either mm-specific or thread-specific: */unsigned long min_flt;unsigned long maj_flt;/* Empty if CONFIG_POSIX_CPUTIMERS=n */struct posix_cputimers posix_cputimers;/* Process credentials: *//* Tracer's credentials at attach: */const struct cred __rcu *ptracer_cred;/* Objective and real subjective task credentials (COW): */const struct cred __rcu *real_cred;/* Effective (overridable) subjective task credentials (COW): */const struct cred __rcu *cred;#ifdef CONFIG_KEYS/* Cached requested key. */struct key *cached_requested_key; #endif/** executable name, excluding path.** - normally initialized setup_new_exec()* - access it with [gs]et_task_comm()* - lock it with task_lock()*/char comm[TASK_COMM_LEN];struct nameidata *nameidata;#ifdef CONFIG_SYSVIPCstruct sysv_sem sysvsem;struct sysv_shm sysvshm; #endif #ifdef CONFIG_DETECT_HUNG_TASKunsigned long last_switch_count;unsigned long last_switch_time; #endif/* Filesystem information: */struct fs_struct *fs;/* Open file information: */struct files_struct *files;/* Namespaces: */struct nsproxy *nsproxy;/* Signal handlers: */struct signal_struct *signal;struct sighand_struct __rcu *sighand;sigset_t blocked;sigset_t real_blocked;/* Restored if set_restore_sigmask() was used: */sigset_t saved_sigmask;struct sigpending pending;unsigned long sas_ss_sp;size_t sas_ss_size;unsigned int sas_ss_flags;struct callback_head *task_works;#ifdef CONFIG_AUDIT #ifdef CONFIG_AUDITSYSCALLstruct audit_context *audit_context; #endifkuid_t loginuid;unsigned int sessionid; #endifstruct seccomp seccomp;/* Thread group tracking: */u64 parent_exec_id;u64 self_exec_id;/* Protection against (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, mempolicy: */spinlock_t alloc_lock;/* Protection of the PI data structures: */raw_spinlock_t pi_lock;struct wake_q_node wake_q;#ifdef CONFIG_RT_MUTEXES/* PI waiters blocked on a rt_mutex held by this task: */struct rb_root_cached pi_waiters;/* Updated under owner's pi_lock and rq lock */struct task_struct *pi_top_task;/* Deadlock detection and priority inheritance handling: */struct rt_mutex_waiter *pi_blocked_on; #endif#ifdef CONFIG_DEBUG_MUTEXES/* Mutex deadlock detection: */struct mutex_waiter *blocked_on; #endif#ifdef CONFIG_DEBUG_ATOMIC_SLEEPint non_block_count; #endif#ifdef CONFIG_TRACE_IRQFLAGSunsigned 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 48ULu64 curr_chain_key;int lockdep_depth;unsigned int lockdep_recursion;struct held_lock held_locks[MAX_LOCK_DEPTH]; #endif#ifdef CONFIG_UBSANunsigned int in_ubsan; #endif/* Journalling filesystem info: */void *journal_info;/* Stacked block device info: */struct bio_list *bio_list;#ifdef CONFIG_BLOCK/* Stack plugging: */struct blk_plug *plug; #endif/* VM state: */struct reclaim_state *reclaim_state;struct backing_dev_info *backing_dev_info;struct io_context *io_context;#ifdef CONFIG_COMPACTIONstruct capture_control *capture_control; #endif/* Ptrace state: */unsigned long ptrace_message;kernel_siginfo_t *last_siginfo;struct task_io_accounting ioac; #ifdef CONFIG_PSI/* Pressure stall state */unsigned int psi_flags; #endif #ifdef CONFIG_TASK_XACCT/* Accumulated RSS usage: */u64 acct_rss_mem1;/* Accumulated virtual memory usage: */u64 acct_vm_mem1;/* stime + utime since last update: */u64 acct_timexpd; #endif #ifdef CONFIG_CPUSETS/* Protected by ->alloc_lock: */nodemask_t mems_allowed;/* Seqence number to catch updates: */seqcount_t mems_allowed_seq;int cpuset_mem_spread_rotor;int cpuset_slab_spread_rotor; #endif #ifdef CONFIG_CGROUPS/* Control Group info protected by css_set_lock: */struct css_set __rcu *cgroups;/* cg_list protected by css_set_lock and tsk->alloc_lock: */struct list_head cg_list; #endif #ifdef CONFIG_X86_CPU_RESCTRLu32 closid;u32 rmid; #endif #ifdef CONFIG_FUTEXstruct robust_list_head __user *robust_list; #ifdef CONFIG_COMPATstruct compat_robust_list_head __user *compat_robust_list; #endifstruct list_head pi_state_list;struct futex_pi_state *pi_state_cache;struct mutex futex_exit_mutex;unsigned int futex_state; #endif #ifdef CONFIG_PERF_EVENTSstruct 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_PREEMPTunsigned long preempt_disable_ip; #endif #ifdef CONFIG_NUMA/* Protected by alloc_lock: */struct mempolicy *mempolicy;short il_prev;short pref_node_fork; #endif #ifdef CONFIG_NUMA_BALANCINGint numa_scan_seq;unsigned int numa_scan_period;unsigned int numa_scan_period_max;int numa_preferred_nid;unsigned long numa_migrate_retry;/* Migration stamp: */u64 node_stamp;u64 last_task_numa_placement;u64 last_sum_exec_runtime;struct callback_head numa_work;/** This pointer is only modified for current in syscall and* pagefault context (and for tasks being destroyed), so it can be read* from any of the following contexts:* - RCU read-side critical section* - current->numa_group from everywhere* - task's runqueue locked, task not running*/struct numa_group __rcu *numa_group;/** numa_faults is an array split into four regions:* faults_memory, faults_cpu, faults_memory_buffer, faults_cpu_buffer* in this precise order.** faults_memory: Exponential decaying average of faults on a per-node* basis. Scheduling placement decisions are made based on these* counts. The values remain static for the duration of a PTE scan.* faults_cpu: Track the nodes the process was running on when a NUMA* hinting fault was incurred.* faults_memory_buffer and faults_cpu_buffer: Record faults per node* during the current scan window. When the scan completes, the counts* in faults_memory and faults_cpu decay and these values are copied.*/unsigned long *numa_faults;unsigned long total_numa_faults;/** numa_faults_locality tracks if faults recorded during the last* scan window were remote/local or failed to migrate. The task scan* period is adapted based on the locality of the faults with different* weights depending on whether they were shared or private faults*/unsigned long numa_faults_locality[3];unsigned long numa_pages_migrated; #endif /* CONFIG_NUMA_BALANCING */#ifdef CONFIG_RSEQstruct rseq __user *rseq;u32 rseq_sig;/** RmW on rseq_event_mask must be performed atomically* with respect to preemption.*/unsigned long rseq_event_mask; #endifstruct tlbflush_unmap_batch tlb_ubc;union {refcount_t rcu_users;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_ACCTstruct task_delay_info *delays; #endif#ifdef CONFIG_FAULT_INJECTIONint make_it_fail;unsigned int fail_nth; #endif/** When (nr_dirtied >= nr_dirtied_pause), it's time to call* balance_dirty_pages() for a dirty throttling pause:*/int nr_dirtied;int nr_dirtied_pause;/* Start of a write-and-pause period: */unsigned long dirty_paused_when;#ifdef CONFIG_LATENCYTOPint 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_KASANunsigned int kasan_depth; #endif#ifdef CONFIG_FUNCTION_GRAPH_TRACER/* Index of current stored address in ret_stack: */int curr_ret_stack;int curr_ret_depth;/* Stack of return addresses for return function tracing: */struct ftrace_ret_stack *ret_stack;/* Timestamp for last schedule: */unsigned long long ftrace_timestamp;/** Number of functions that haven't been traced* because of depth overrun:*/atomic_t trace_overrun;/* Pause tracing: */atomic_t tracing_graph_pause; #endif#ifdef CONFIG_TRACING/* State flags for use by tracers: */unsigned long trace;/* Bitmask and counter of trace recursion: */unsigned long trace_recursion; #endif /* CONFIG_TRACING */#ifdef CONFIG_KCOV/* See kernel/kcov.c for more details. *//* Coverage collection mode enabled for this task (0 if disabled): */unsigned int kcov_mode;/* Size of the kcov_area: */unsigned int kcov_size;/* Buffer for coverage collection: */void *kcov_area;/* KCOV descriptor wired with this task or NULL: */struct kcov *kcov;/* KCOV common handle for remote coverage collection: */u64 kcov_handle;/* KCOV sequence number: */int kcov_sequence; #endif#ifdef CONFIG_MEMCGstruct mem_cgroup *memcg_in_oom;gfp_t memcg_oom_gfp_mask;int memcg_oom_order;/* Number of pages to reclaim on returning to userland: */unsigned int memcg_nr_pages_over_high;/* Used by memcontrol for targeted memcg charge: */struct mem_cgroup *active_memcg; #endif#ifdef CONFIG_BLK_CGROUPstruct request_queue *throttle_queue; #endif#ifdef CONFIG_UPROBESstruct 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_SLEEPunsigned long task_state_change; #endifint pagefault_disabled; #ifdef CONFIG_MMUstruct task_struct *oom_reaper_list; #endif #ifdef CONFIG_VMAP_STACKstruct vm_struct *stack_vm_area; #endif #ifdef CONFIG_THREAD_INFO_IN_TASK/* A live task holds one reference: */refcount_t stack_refcount; #endif #ifdef CONFIG_LIVEPATCHint patch_state; #endif #ifdef CONFIG_SECURITY/* Used by LSM modules for access restriction: */void *security; #endif#ifdef CONFIG_GCC_PLUGIN_STACKLEAKunsigned long lowest_stack;unsigned long prev_lowest_stack; #endif/** New fields for task_struct should be added above here, so that* they are included in the randomized portion of task_struct.*/randomized_struct_fields_end/* CPU-specific state of this task: */struct thread_struct thread;/** WARNING: on x86, 'thread_struct' contains a variable-sized* structure. It *MUST* be at the end of 'task_struct'.** Do not put anything below here!*/ };

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