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0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef _LINUX_SCHED_SIGNAL_H
0003 #define _LINUX_SCHED_SIGNAL_H
0004 
0005 #include <linux/rculist.h>
0006 #include <linux/signal.h>
0007 #include <linux/sched.h>
0008 #include <linux/sched/jobctl.h>
0009 #include <linux/sched/task.h>
0010 #include <linux/cred.h>
0011 #include <linux/refcount.h>
0012 #include <linux/posix-timers.h>
0013 #include <linux/mm_types.h>
0014 #include <asm/ptrace.h>
0015 
0016 /*
0017  * Types defining task->signal and task->sighand and APIs using them:
0018  */
0019 
0020 struct sighand_struct {
0021     spinlock_t      siglock;
0022     refcount_t      count;
0023     wait_queue_head_t   signalfd_wqh;
0024     struct k_sigaction  action[_NSIG];
0025 };
0026 
0027 /*
0028  * Per-process accounting stats:
0029  */
0030 struct pacct_struct {
0031     int         ac_flag;
0032     long            ac_exitcode;
0033     unsigned long       ac_mem;
0034     u64         ac_utime, ac_stime;
0035     unsigned long       ac_minflt, ac_majflt;
0036 };
0037 
0038 struct cpu_itimer {
0039     u64 expires;
0040     u64 incr;
0041 };
0042 
0043 /*
0044  * This is the atomic variant of task_cputime, which can be used for
0045  * storing and updating task_cputime statistics without locking.
0046  */
0047 struct task_cputime_atomic {
0048     atomic64_t utime;
0049     atomic64_t stime;
0050     atomic64_t sum_exec_runtime;
0051 };
0052 
0053 #define INIT_CPUTIME_ATOMIC \
0054     (struct task_cputime_atomic) {              \
0055         .utime = ATOMIC64_INIT(0),          \
0056         .stime = ATOMIC64_INIT(0),          \
0057         .sum_exec_runtime = ATOMIC64_INIT(0),       \
0058     }
0059 /**
0060  * struct thread_group_cputimer - thread group interval timer counts
0061  * @cputime_atomic: atomic thread group interval timers.
0062  *
0063  * This structure contains the version of task_cputime, above, that is
0064  * used for thread group CPU timer calculations.
0065  */
0066 struct thread_group_cputimer {
0067     struct task_cputime_atomic cputime_atomic;
0068 };
0069 
0070 struct multiprocess_signals {
0071     sigset_t signal;
0072     struct hlist_node node;
0073 };
0074 
0075 struct core_thread {
0076     struct task_struct *task;
0077     struct core_thread *next;
0078 };
0079 
0080 struct core_state {
0081     atomic_t nr_threads;
0082     struct core_thread dumper;
0083     struct completion startup;
0084 };
0085 
0086 /*
0087  * NOTE! "signal_struct" does not have its own
0088  * locking, because a shared signal_struct always
0089  * implies a shared sighand_struct, so locking
0090  * sighand_struct is always a proper superset of
0091  * the locking of signal_struct.
0092  */
0093 struct signal_struct {
0094     refcount_t      sigcnt;
0095     atomic_t        live;
0096     int         nr_threads;
0097     struct list_head    thread_head;
0098 
0099     wait_queue_head_t   wait_chldexit;  /* for wait4() */
0100 
0101     /* current thread group signal load-balancing target: */
0102     struct task_struct  *curr_target;
0103 
0104     /* shared signal handling: */
0105     struct sigpending   shared_pending;
0106 
0107     /* For collecting multiprocess signals during fork */
0108     struct hlist_head   multiprocess;
0109 
0110     /* thread group exit support */
0111     int         group_exit_code;
0112     /* notify group_exec_task when notify_count is less or equal to 0 */
0113     int         notify_count;
0114     struct task_struct  *group_exec_task;
0115 
0116     /* thread group stop support, overloads group_exit_code too */
0117     int         group_stop_count;
0118     unsigned int        flags; /* see SIGNAL_* flags below */
0119 
0120     struct core_state *core_state; /* coredumping support */
0121 
0122     /*
0123      * PR_SET_CHILD_SUBREAPER marks a process, like a service
0124      * manager, to re-parent orphan (double-forking) child processes
0125      * to this process instead of 'init'. The service manager is
0126      * able to receive SIGCHLD signals and is able to investigate
0127      * the process until it calls wait(). All children of this
0128      * process will inherit a flag if they should look for a
0129      * child_subreaper process at exit.
0130      */
0131     unsigned int        is_child_subreaper:1;
0132     unsigned int        has_child_subreaper:1;
0133 
0134 #ifdef CONFIG_POSIX_TIMERS
0135 
0136     /* POSIX.1b Interval Timers */
0137     int         posix_timer_id;
0138     struct list_head    posix_timers;
0139 
0140     /* ITIMER_REAL timer for the process */
0141     struct hrtimer real_timer;
0142     ktime_t it_real_incr;
0143 
0144     /*
0145      * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
0146      * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
0147      * values are defined to 0 and 1 respectively
0148      */
0149     struct cpu_itimer it[2];
0150 
0151     /*
0152      * Thread group totals for process CPU timers.
0153      * See thread_group_cputimer(), et al, for details.
0154      */
0155     struct thread_group_cputimer cputimer;
0156 
0157 #endif
0158     /* Empty if CONFIG_POSIX_TIMERS=n */
0159     struct posix_cputimers posix_cputimers;
0160 
0161     /* PID/PID hash table linkage. */
0162     struct pid *pids[PIDTYPE_MAX];
0163 
0164 #ifdef CONFIG_NO_HZ_FULL
0165     atomic_t tick_dep_mask;
0166 #endif
0167 
0168     struct pid *tty_old_pgrp;
0169 
0170     /* boolean value for session group leader */
0171     int leader;
0172 
0173     struct tty_struct *tty; /* NULL if no tty */
0174 
0175 #ifdef CONFIG_SCHED_AUTOGROUP
0176     struct autogroup *autogroup;
0177 #endif
0178     /*
0179      * Cumulative resource counters for dead threads in the group,
0180      * and for reaped dead child processes forked by this group.
0181      * Live threads maintain their own counters and add to these
0182      * in __exit_signal, except for the group leader.
0183      */
0184     seqlock_t stats_lock;
0185     u64 utime, stime, cutime, cstime;
0186     u64 gtime;
0187     u64 cgtime;
0188     struct prev_cputime prev_cputime;
0189     unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
0190     unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
0191     unsigned long inblock, oublock, cinblock, coublock;
0192     unsigned long maxrss, cmaxrss;
0193     struct task_io_accounting ioac;
0194 
0195     /*
0196      * Cumulative ns of schedule CPU time fo dead threads in the
0197      * group, not including a zombie group leader, (This only differs
0198      * from jiffies_to_ns(utime + stime) if sched_clock uses something
0199      * other than jiffies.)
0200      */
0201     unsigned long long sum_sched_runtime;
0202 
0203     /*
0204      * We don't bother to synchronize most readers of this at all,
0205      * because there is no reader checking a limit that actually needs
0206      * to get both rlim_cur and rlim_max atomically, and either one
0207      * alone is a single word that can safely be read normally.
0208      * getrlimit/setrlimit use task_lock(current->group_leader) to
0209      * protect this instead of the siglock, because they really
0210      * have no need to disable irqs.
0211      */
0212     struct rlimit rlim[RLIM_NLIMITS];
0213 
0214 #ifdef CONFIG_BSD_PROCESS_ACCT
0215     struct pacct_struct pacct;  /* per-process accounting information */
0216 #endif
0217 #ifdef CONFIG_TASKSTATS
0218     struct taskstats *stats;
0219 #endif
0220 #ifdef CONFIG_AUDIT
0221     unsigned audit_tty;
0222     struct tty_audit_buf *tty_audit_buf;
0223 #endif
0224 
0225     /*
0226      * Thread is the potential origin of an oom condition; kill first on
0227      * oom
0228      */
0229     bool oom_flag_origin;
0230     short oom_score_adj;        /* OOM kill score adjustment */
0231     short oom_score_adj_min;    /* OOM kill score adjustment min value.
0232                      * Only settable by CAP_SYS_RESOURCE. */
0233     struct mm_struct *oom_mm;   /* recorded mm when the thread group got
0234                      * killed by the oom killer */
0235 
0236     struct mutex cred_guard_mutex;  /* guard against foreign influences on
0237                      * credential calculations
0238                      * (notably. ptrace)
0239                      * Deprecated do not use in new code.
0240                      * Use exec_update_lock instead.
0241                      */
0242     struct rw_semaphore exec_update_lock;   /* Held while task_struct is
0243                          * being updated during exec,
0244                          * and may have inconsistent
0245                          * permissions.
0246                          */
0247 } __randomize_layout;
0248 
0249 /*
0250  * Bits in flags field of signal_struct.
0251  */
0252 #define SIGNAL_STOP_STOPPED 0x00000001 /* job control stop in effect */
0253 #define SIGNAL_STOP_CONTINUED   0x00000002 /* SIGCONT since WCONTINUED reap */
0254 #define SIGNAL_GROUP_EXIT   0x00000004 /* group exit in progress */
0255 /*
0256  * Pending notifications to parent.
0257  */
0258 #define SIGNAL_CLD_STOPPED  0x00000010
0259 #define SIGNAL_CLD_CONTINUED    0x00000020
0260 #define SIGNAL_CLD_MASK     (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
0261 
0262 #define SIGNAL_UNKILLABLE   0x00000040 /* for init: ignore fatal signals */
0263 
0264 #define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
0265               SIGNAL_STOP_CONTINUED)
0266 
0267 static inline void signal_set_stop_flags(struct signal_struct *sig,
0268                      unsigned int flags)
0269 {
0270     WARN_ON(sig->flags & SIGNAL_GROUP_EXIT);
0271     sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
0272 }
0273 
0274 extern void flush_signals(struct task_struct *);
0275 extern void ignore_signals(struct task_struct *);
0276 extern void flush_signal_handlers(struct task_struct *, int force_default);
0277 extern int dequeue_signal(struct task_struct *task, sigset_t *mask,
0278               kernel_siginfo_t *info, enum pid_type *type);
0279 
0280 static inline int kernel_dequeue_signal(void)
0281 {
0282     struct task_struct *task = current;
0283     kernel_siginfo_t __info;
0284     enum pid_type __type;
0285     int ret;
0286 
0287     spin_lock_irq(&task->sighand->siglock);
0288     ret = dequeue_signal(task, &task->blocked, &__info, &__type);
0289     spin_unlock_irq(&task->sighand->siglock);
0290 
0291     return ret;
0292 }
0293 
0294 static inline void kernel_signal_stop(void)
0295 {
0296     spin_lock_irq(&current->sighand->siglock);
0297     if (current->jobctl & JOBCTL_STOP_DEQUEUED) {
0298         current->jobctl |= JOBCTL_STOPPED;
0299         set_special_state(TASK_STOPPED);
0300     }
0301     spin_unlock_irq(&current->sighand->siglock);
0302 
0303     schedule();
0304 }
0305 #ifdef __ia64__
0306 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
0307 #else
0308 # define ___ARCH_SI_IA64(_a1, _a2, _a3)
0309 #endif
0310 
0311 int force_sig_fault_to_task(int sig, int code, void __user *addr
0312     ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
0313     , struct task_struct *t);
0314 int force_sig_fault(int sig, int code, void __user *addr
0315     ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
0316 int send_sig_fault(int sig, int code, void __user *addr
0317     ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
0318     , struct task_struct *t);
0319 
0320 int force_sig_mceerr(int code, void __user *, short);
0321 int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
0322 
0323 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
0324 int force_sig_pkuerr(void __user *addr, u32 pkey);
0325 int send_sig_perf(void __user *addr, u32 type, u64 sig_data);
0326 
0327 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
0328 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
0329 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
0330             struct task_struct *t);
0331 int force_sig_seccomp(int syscall, int reason, bool force_coredump);
0332 
0333 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
0334 extern void force_sigsegv(int sig);
0335 extern int force_sig_info(struct kernel_siginfo *);
0336 extern int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp);
0337 extern int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid);
0338 extern int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr, struct pid *,
0339                 const struct cred *);
0340 extern int kill_pgrp(struct pid *pid, int sig, int priv);
0341 extern int kill_pid(struct pid *pid, int sig, int priv);
0342 extern __must_check bool do_notify_parent(struct task_struct *, int);
0343 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
0344 extern void force_sig(int);
0345 extern void force_fatal_sig(int);
0346 extern void force_exit_sig(int);
0347 extern int send_sig(int, struct task_struct *, int);
0348 extern int zap_other_threads(struct task_struct *p);
0349 extern struct sigqueue *sigqueue_alloc(void);
0350 extern void sigqueue_free(struct sigqueue *);
0351 extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type);
0352 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
0353 
0354 static inline void clear_notify_signal(void)
0355 {
0356     clear_thread_flag(TIF_NOTIFY_SIGNAL);
0357     smp_mb__after_atomic();
0358 }
0359 
0360 /*
0361  * Returns 'true' if kick_process() is needed to force a transition from
0362  * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work.
0363  */
0364 static inline bool __set_notify_signal(struct task_struct *task)
0365 {
0366     return !test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
0367            !wake_up_state(task, TASK_INTERRUPTIBLE);
0368 }
0369 
0370 /*
0371  * Called to break out of interruptible wait loops, and enter the
0372  * exit_to_user_mode_loop().
0373  */
0374 static inline void set_notify_signal(struct task_struct *task)
0375 {
0376     if (__set_notify_signal(task))
0377         kick_process(task);
0378 }
0379 
0380 static inline int restart_syscall(void)
0381 {
0382     set_tsk_thread_flag(current, TIF_SIGPENDING);
0383     return -ERESTARTNOINTR;
0384 }
0385 
0386 static inline int task_sigpending(struct task_struct *p)
0387 {
0388     return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
0389 }
0390 
0391 static inline int signal_pending(struct task_struct *p)
0392 {
0393     /*
0394      * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
0395      * behavior in terms of ensuring that we break out of wait loops
0396      * so that notify signal callbacks can be processed.
0397      */
0398     if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
0399         return 1;
0400     return task_sigpending(p);
0401 }
0402 
0403 static inline int __fatal_signal_pending(struct task_struct *p)
0404 {
0405     return unlikely(sigismember(&p->pending.signal, SIGKILL));
0406 }
0407 
0408 static inline int fatal_signal_pending(struct task_struct *p)
0409 {
0410     return task_sigpending(p) && __fatal_signal_pending(p);
0411 }
0412 
0413 static inline int signal_pending_state(unsigned int state, struct task_struct *p)
0414 {
0415     if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
0416         return 0;
0417     if (!signal_pending(p))
0418         return 0;
0419 
0420     return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
0421 }
0422 
0423 /*
0424  * This should only be used in fault handlers to decide whether we
0425  * should stop the current fault routine to handle the signals
0426  * instead, especially with the case where we've got interrupted with
0427  * a VM_FAULT_RETRY.
0428  */
0429 static inline bool fault_signal_pending(vm_fault_t fault_flags,
0430                     struct pt_regs *regs)
0431 {
0432     return unlikely((fault_flags & VM_FAULT_RETRY) &&
0433             (fatal_signal_pending(current) ||
0434              (user_mode(regs) && signal_pending(current))));
0435 }
0436 
0437 /*
0438  * Reevaluate whether the task has signals pending delivery.
0439  * Wake the task if so.
0440  * This is required every time the blocked sigset_t changes.
0441  * callers must hold sighand->siglock.
0442  */
0443 extern void recalc_sigpending_and_wake(struct task_struct *t);
0444 extern void recalc_sigpending(void);
0445 extern void calculate_sigpending(void);
0446 
0447 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
0448 
0449 static inline void signal_wake_up(struct task_struct *t, bool fatal)
0450 {
0451     unsigned int state = 0;
0452     if (fatal && !(t->jobctl & JOBCTL_PTRACE_FROZEN)) {
0453         t->jobctl &= ~(JOBCTL_STOPPED | JOBCTL_TRACED);
0454         state = TASK_WAKEKILL | __TASK_TRACED;
0455     }
0456     signal_wake_up_state(t, state);
0457 }
0458 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
0459 {
0460     unsigned int state = 0;
0461     if (resume) {
0462         t->jobctl &= ~JOBCTL_TRACED;
0463         state = __TASK_TRACED;
0464     }
0465     signal_wake_up_state(t, state);
0466 }
0467 
0468 void task_join_group_stop(struct task_struct *task);
0469 
0470 #ifdef TIF_RESTORE_SIGMASK
0471 /*
0472  * Legacy restore_sigmask accessors.  These are inefficient on
0473  * SMP architectures because they require atomic operations.
0474  */
0475 
0476 /**
0477  * set_restore_sigmask() - make sure saved_sigmask processing gets done
0478  *
0479  * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
0480  * will run before returning to user mode, to process the flag.  For
0481  * all callers, TIF_SIGPENDING is already set or it's no harm to set
0482  * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
0483  * arch code will notice on return to user mode, in case those bits
0484  * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
0485  * signal code always gets run when TIF_RESTORE_SIGMASK is set.
0486  */
0487 static inline void set_restore_sigmask(void)
0488 {
0489     set_thread_flag(TIF_RESTORE_SIGMASK);
0490 }
0491 
0492 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
0493 {
0494     clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
0495 }
0496 
0497 static inline void clear_restore_sigmask(void)
0498 {
0499     clear_thread_flag(TIF_RESTORE_SIGMASK);
0500 }
0501 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
0502 {
0503     return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
0504 }
0505 static inline bool test_restore_sigmask(void)
0506 {
0507     return test_thread_flag(TIF_RESTORE_SIGMASK);
0508 }
0509 static inline bool test_and_clear_restore_sigmask(void)
0510 {
0511     return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
0512 }
0513 
0514 #else   /* TIF_RESTORE_SIGMASK */
0515 
0516 /* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
0517 static inline void set_restore_sigmask(void)
0518 {
0519     current->restore_sigmask = true;
0520 }
0521 static inline void clear_tsk_restore_sigmask(struct task_struct *task)
0522 {
0523     task->restore_sigmask = false;
0524 }
0525 static inline void clear_restore_sigmask(void)
0526 {
0527     current->restore_sigmask = false;
0528 }
0529 static inline bool test_restore_sigmask(void)
0530 {
0531     return current->restore_sigmask;
0532 }
0533 static inline bool test_tsk_restore_sigmask(struct task_struct *task)
0534 {
0535     return task->restore_sigmask;
0536 }
0537 static inline bool test_and_clear_restore_sigmask(void)
0538 {
0539     if (!current->restore_sigmask)
0540         return false;
0541     current->restore_sigmask = false;
0542     return true;
0543 }
0544 #endif
0545 
0546 static inline void restore_saved_sigmask(void)
0547 {
0548     if (test_and_clear_restore_sigmask())
0549         __set_current_blocked(&current->saved_sigmask);
0550 }
0551 
0552 extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
0553 
0554 static inline void restore_saved_sigmask_unless(bool interrupted)
0555 {
0556     if (interrupted)
0557         WARN_ON(!signal_pending(current));
0558     else
0559         restore_saved_sigmask();
0560 }
0561 
0562 static inline sigset_t *sigmask_to_save(void)
0563 {
0564     sigset_t *res = &current->blocked;
0565     if (unlikely(test_restore_sigmask()))
0566         res = &current->saved_sigmask;
0567     return res;
0568 }
0569 
0570 static inline int kill_cad_pid(int sig, int priv)
0571 {
0572     return kill_pid(cad_pid, sig, priv);
0573 }
0574 
0575 /* These can be the second arg to send_sig_info/send_group_sig_info.  */
0576 #define SEND_SIG_NOINFO ((struct kernel_siginfo *) 0)
0577 #define SEND_SIG_PRIV   ((struct kernel_siginfo *) 1)
0578 
0579 static inline int __on_sig_stack(unsigned long sp)
0580 {
0581 #ifdef CONFIG_STACK_GROWSUP
0582     return sp >= current->sas_ss_sp &&
0583         sp - current->sas_ss_sp < current->sas_ss_size;
0584 #else
0585     return sp > current->sas_ss_sp &&
0586         sp - current->sas_ss_sp <= current->sas_ss_size;
0587 #endif
0588 }
0589 
0590 /*
0591  * True if we are on the alternate signal stack.
0592  */
0593 static inline int on_sig_stack(unsigned long sp)
0594 {
0595     /*
0596      * If the signal stack is SS_AUTODISARM then, by construction, we
0597      * can't be on the signal stack unless user code deliberately set
0598      * SS_AUTODISARM when we were already on it.
0599      *
0600      * This improves reliability: if user state gets corrupted such that
0601      * the stack pointer points very close to the end of the signal stack,
0602      * then this check will enable the signal to be handled anyway.
0603      */
0604     if (current->sas_ss_flags & SS_AUTODISARM)
0605         return 0;
0606 
0607     return __on_sig_stack(sp);
0608 }
0609 
0610 static inline int sas_ss_flags(unsigned long sp)
0611 {
0612     if (!current->sas_ss_size)
0613         return SS_DISABLE;
0614 
0615     return on_sig_stack(sp) ? SS_ONSTACK : 0;
0616 }
0617 
0618 static inline void sas_ss_reset(struct task_struct *p)
0619 {
0620     p->sas_ss_sp = 0;
0621     p->sas_ss_size = 0;
0622     p->sas_ss_flags = SS_DISABLE;
0623 }
0624 
0625 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
0626 {
0627     if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
0628 #ifdef CONFIG_STACK_GROWSUP
0629         return current->sas_ss_sp;
0630 #else
0631         return current->sas_ss_sp + current->sas_ss_size;
0632 #endif
0633     return sp;
0634 }
0635 
0636 extern void __cleanup_sighand(struct sighand_struct *);
0637 extern void flush_itimer_signals(void);
0638 
0639 #define tasklist_empty() \
0640     list_empty(&init_task.tasks)
0641 
0642 #define next_task(p) \
0643     list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
0644 
0645 #define for_each_process(p) \
0646     for (p = &init_task ; (p = next_task(p)) != &init_task ; )
0647 
0648 extern bool current_is_single_threaded(void);
0649 
0650 /*
0651  * Careful: do_each_thread/while_each_thread is a double loop so
0652  *          'break' will not work as expected - use goto instead.
0653  */
0654 #define do_each_thread(g, t) \
0655     for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
0656 
0657 #define while_each_thread(g, t) \
0658     while ((t = next_thread(t)) != g)
0659 
0660 #define __for_each_thread(signal, t)    \
0661     list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
0662 
0663 #define for_each_thread(p, t)       \
0664     __for_each_thread((p)->signal, t)
0665 
0666 /* Careful: this is a double loop, 'break' won't work as expected. */
0667 #define for_each_process_thread(p, t)   \
0668     for_each_process(p) for_each_thread(p, t)
0669 
0670 typedef int (*proc_visitor)(struct task_struct *p, void *data);
0671 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
0672 
0673 static inline
0674 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
0675 {
0676     struct pid *pid;
0677     if (type == PIDTYPE_PID)
0678         pid = task_pid(task);
0679     else
0680         pid = task->signal->pids[type];
0681     return pid;
0682 }
0683 
0684 static inline struct pid *task_tgid(struct task_struct *task)
0685 {
0686     return task->signal->pids[PIDTYPE_TGID];
0687 }
0688 
0689 /*
0690  * Without tasklist or RCU lock it is not safe to dereference
0691  * the result of task_pgrp/task_session even if task == current,
0692  * we can race with another thread doing sys_setsid/sys_setpgid.
0693  */
0694 static inline struct pid *task_pgrp(struct task_struct *task)
0695 {
0696     return task->signal->pids[PIDTYPE_PGID];
0697 }
0698 
0699 static inline struct pid *task_session(struct task_struct *task)
0700 {
0701     return task->signal->pids[PIDTYPE_SID];
0702 }
0703 
0704 static inline int get_nr_threads(struct task_struct *task)
0705 {
0706     return task->signal->nr_threads;
0707 }
0708 
0709 static inline bool thread_group_leader(struct task_struct *p)
0710 {
0711     return p->exit_signal >= 0;
0712 }
0713 
0714 static inline
0715 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
0716 {
0717     return p1->signal == p2->signal;
0718 }
0719 
0720 static inline struct task_struct *next_thread(const struct task_struct *p)
0721 {
0722     return list_entry_rcu(p->thread_group.next,
0723                   struct task_struct, thread_group);
0724 }
0725 
0726 static inline int thread_group_empty(struct task_struct *p)
0727 {
0728     return list_empty(&p->thread_group);
0729 }
0730 
0731 #define delay_group_leader(p) \
0732         (thread_group_leader(p) && !thread_group_empty(p))
0733 
0734 extern bool thread_group_exited(struct pid *pid);
0735 
0736 extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
0737                             unsigned long *flags);
0738 
0739 static inline struct sighand_struct *lock_task_sighand(struct task_struct *task,
0740                                unsigned long *flags)
0741 {
0742     struct sighand_struct *ret;
0743 
0744     ret = __lock_task_sighand(task, flags);
0745     (void)__cond_lock(&task->sighand->siglock, ret);
0746     return ret;
0747 }
0748 
0749 static inline void unlock_task_sighand(struct task_struct *task,
0750                         unsigned long *flags)
0751 {
0752     spin_unlock_irqrestore(&task->sighand->siglock, *flags);
0753 }
0754 
0755 #ifdef CONFIG_LOCKDEP
0756 extern void lockdep_assert_task_sighand_held(struct task_struct *task);
0757 #else
0758 static inline void lockdep_assert_task_sighand_held(struct task_struct *task) { }
0759 #endif
0760 
0761 static inline unsigned long task_rlimit(const struct task_struct *task,
0762         unsigned int limit)
0763 {
0764     return READ_ONCE(task->signal->rlim[limit].rlim_cur);
0765 }
0766 
0767 static inline unsigned long task_rlimit_max(const struct task_struct *task,
0768         unsigned int limit)
0769 {
0770     return READ_ONCE(task->signal->rlim[limit].rlim_max);
0771 }
0772 
0773 static inline unsigned long rlimit(unsigned int limit)
0774 {
0775     return task_rlimit(current, limit);
0776 }
0777 
0778 static inline unsigned long rlimit_max(unsigned int limit)
0779 {
0780     return task_rlimit_max(current, limit);
0781 }
0782 
0783 #endif /* _LINUX_SCHED_SIGNAL_H */
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