struct signal_struct {atomic_t     count;atomic_t      live;wait_queue_head_t  wait_chldexit;  /* for wait4() *//* current thread group signal load-balancing target: */struct task_struct *curr_target;/* shared signal handling: */struct sigpending shared_pending;/* thread group exit support */int           group_exit_code;/* overloaded:* - notify group_exit_task when ->count is equal to notify_count* - everyone except group_exit_task is stopped during signal delivery*   of fatal signals, group_exit_task processes the signal.*/struct task_struct   *group_exit_task;int            notify_count;/* thread group stop support, overloads group_exit_code too */int          group_stop_count;unsigned int       flags; /* see SIGNAL_* flags below *//* POSIX.1b Interval Timers */struct list_head posix_timers;/* ITIMER_REAL timer for the process */struct hrtimer real_timer;struct pid *leader_pid;ktime_t it_real_incr;/* ITIMER_PROF and ITIMER_VIRTUAL timers for the process */cputime_t it_prof_expires, it_virt_expires;cputime_t it_prof_incr, it_virt_incr;/* job control IDs *//** pgrp and session fields are deprecated.* use the task_session_Xnr and task_pgrp_Xnr routines below*/union {pid_t pgrp __deprecated;pid_t __pgrp;};struct pid *tty_old_pgrp;union {pid_t session __deprecated;pid_t __session;};/* boolean value for session group leader */int leader;struct tty_struct *tty; /* NULL if no tty *//** Cumulative resource counters for dead threads in the group,* and for reaped dead child processes forked by this group.* Live threads maintain their own counters and add to these* in __exit_signal, except for the group leader.*/cputime_t utime, stime, cutime, cstime;cputime_t gtime;cputime_t cgtime;unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;unsigned long inblock, oublock, cinblock, coublock;/** Cumulative ns of scheduled CPU time for dead threads in the* group, not including a zombie group leader.  (This only differs* from jiffies_to_ns(utime + stime) if sched_clock uses something* other than jiffies.)*/unsigned long long sum_sched_runtime;/** We don't bother to synchronize most readers of this at all,* because there is no reader checking a limit that actually needs* to get both rlim_cur and rlim_max atomically, and either one* alone is a single word that can safely be read normally.* getrlimit/setrlimit use task_lock(current->group_leader) to* protect this instead of the siglock, because they really* have no need to disable irqs.*/struct rlimit rlim[RLIM_NLIMITS];struct list_head cpu_timers[3];/* keep the process-shared keyrings here so that they do the right* thing in threads created with CLONE_THREAD */
#ifdef CONFIG_KEYSstruct key *session_keyring;  /* keyring inherited over fork */struct key *process_keyring;   /* keyring private to this process */
#endif
#ifdef CONFIG_BSD_PROCESS_ACCTstruct pacct_struct pacct;    /* per-process accounting information */
#endif
#ifdef CONFIG_TASKSTATSstruct taskstats *stats;
#endif
#ifdef CONFIG_AUDITunsigned audit_tty;struct tty_audit_buf *tty_audit_buf;
#endif
};

struct sighand_struct {atomic_t       count;struct k_sigaction    action[_NSIG];spinlock_t        siglock;wait_queue_head_t   signalfd_wqh;
};

struct sigpending {struct list_head list;sigset_t signal;
};

struct task_struct {
    .......
    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;
    ......
}