/* * linux/kernel/exit.c * * Copyright (C) 1991, 1992 Linus Torvalds */ #include #include #include #include #include #include #ifdef CONFIG_BSD_PROCESS_ACCT #include #endif #include #include #include extern void sem_exit (void); extern struct task_struct *child_reaper; int getrusage(struct task_struct *, int, struct rusage *); void release_task(struct task_struct * p) { if (p != current) { #ifdef CONFIG_SMP /* * Wait to make sure the process isn't on the * runqueue (active on some other CPU still) */ for (;;) { task_lock(p); if (!p->has_cpu) break; task_unlock(p); do { barrier(); } while (p->has_cpu); } task_unlock(p); #endif atomic_dec(&p->user->processes); free_uid(p->user); unhash_process(p); release_thread(p); current->cmin_flt += p->min_flt + p->cmin_flt; current->cmaj_flt += p->maj_flt + p->cmaj_flt; current->cnswap += p->nswap + p->cnswap; /* * Potentially available timeslices are retrieved * here - this way the parent does not get penalized * for creating too many processes. * * (this cannot be used to artificially 'generate' * timeslices, because any timeslice recovered here * was given away by the parent in the first place.) */ current->counter += p->counter; if (current->counter >= MAX_COUNTER) current->counter = MAX_COUNTER; free_task_struct(p); } else { printk("task releasing itself\n"); } } /* * This checks not only the pgrp, but falls back on the pid if no * satisfactory pgrp is found. I dunno - gdb doesn't work correctly * without this... */ int session_of_pgrp(int pgrp) { struct task_struct *p; int fallback; fallback = -1; read_lock(&tasklist_lock); for_each_task(p) { if (p->session <= 0) continue; if (p->pgrp == pgrp) { fallback = p->session; break; } if (p->pid == pgrp) fallback = p->session; } read_unlock(&tasklist_lock); return fallback; } /* * Determine if a process group is "orphaned", according to the POSIX * definition in 2.2.2.52. Orphaned process groups are not to be affected * by terminal-generated stop signals. Newly orphaned process groups are * to receive a SIGHUP and a SIGCONT. * * "I ask you, have you ever known what it is to be an orphan?" */ static int will_become_orphaned_pgrp(int pgrp, struct task_struct * ignored_task) { struct task_struct *p; read_lock(&tasklist_lock); for_each_task(p) { if ((p == ignored_task) || (p->pgrp != pgrp) || (p->state == TASK_ZOMBIE) || (p->p_pptr->pid == 1)) continue; if ((p->p_pptr->pgrp != pgrp) && (p->p_pptr->session == p->session)) { read_unlock(&tasklist_lock); return 0; } } read_unlock(&tasklist_lock); return 1; /* (sighing) "Often!" */ } int is_orphaned_pgrp(int pgrp) { return will_become_orphaned_pgrp(pgrp, 0); } static inline int has_stopped_jobs(int pgrp) { int retval = 0; struct task_struct * p; read_lock(&tasklist_lock); for_each_task(p) { if (p->pgrp != pgrp) continue; if (p->state != TASK_STOPPED) continue; retval = 1; break; } read_unlock(&tasklist_lock); return retval; } /* * When we die, we re-parent all our children. * Try to give them to another thread in our process * group, and if no such member exists, give it to * the global child reaper process (ie "init") */ static inline void forget_original_parent(struct task_struct * father) { struct task_struct * p, *reaper; read_lock(&tasklist_lock); /* Next in our thread group */ reaper = next_thread(father); if (reaper == father) reaper = child_reaper; for_each_task(p) { if (p->p_opptr == father) { /* We dont want people slaying init */ p->exit_signal = SIGCHLD; p->self_exec_id++; p->p_opptr = reaper; if (p->pdeath_signal) send_sig(p->pdeath_signal, p, 0); } } read_unlock(&tasklist_lock); } static inline void close_files(struct files_struct * files) { int i, j; j = 0; for (;;) { unsigned long set; i = j * __NFDBITS; if (i >= files->max_fdset || i >= files->max_fds) break; set = files->open_fds->fds_bits[j++]; while (set) { if (set & 1) { struct file * file = xchg(&files->fd[i], NULL); if (file) filp_close(file, files); } i++; set >>= 1; } } } void put_files_struct(struct files_struct *files) { if (atomic_dec_and_test(&files->count)) { close_files(files); /* * Free the fd and fdset arrays if we expanded them. */ if (files->fd != &files->fd_array[0]) free_fd_array(files->fd, files->max_fds); if (files->max_fdset > __FD_SETSIZE) { free_fdset(files->open_fds, files->max_fdset); free_fdset(files->close_on_exec, files->max_fdset); } kmem_cache_free(files_cachep, files); } } static inline void __exit_files(struct task_struct *tsk) { struct files_struct * files = tsk->files; if (files) { task_lock(tsk); tsk->files = NULL; task_unlock(tsk); put_files_struct(files); } } void exit_files(struct task_struct *tsk) { __exit_files(tsk); } static inline void __put_fs_struct(struct fs_struct *fs) { /* No need to hold fs->lock if we are killing it */ if (atomic_dec_and_test(&fs->count)) { dput(fs->root); mntput(fs->rootmnt); dput(fs->pwd); mntput(fs->pwdmnt); if (fs->altroot) { dput(fs->altroot); mntput(fs->altrootmnt); } kmem_cache_free(fs_cachep, fs); } } void put_fs_struct(struct fs_struct *fs) { __put_fs_struct(fs); } static inline void __exit_fs(struct task_struct *tsk) { struct fs_struct * fs = tsk->fs; if (fs) { task_lock(tsk); tsk->fs = NULL; task_unlock(tsk); __put_fs_struct(fs); } } void exit_fs(struct task_struct *tsk) { __exit_fs(tsk); } /* * We can use these to temporarily drop into * "lazy TLB" mode and back. */ struct mm_struct * start_lazy_tlb(void) { struct mm_struct *mm = current->mm; current->mm = NULL; /* active_mm is still 'mm' */ atomic_inc(&mm->mm_count); enter_lazy_tlb(mm, current, smp_processor_id()); return mm; } void end_lazy_tlb(struct mm_struct *mm) { struct mm_struct *active_mm = current->active_mm; current->mm = mm; if (mm != active_mm) { current->active_mm = mm; activate_mm(active_mm, mm); } mmdrop(active_mm); } /* * Turn us into a lazy TLB process if we * aren't already.. */ static inline void __exit_mm(struct task_struct * tsk) { struct mm_struct * mm = tsk->mm; mm_release(); if (mm) { atomic_inc(&mm->mm_count); if (mm != tsk->active_mm) BUG(); /* more a memory barrier than a real lock */ task_lock(tsk); tsk->mm = NULL; task_unlock(tsk); enter_lazy_tlb(mm, current, smp_processor_id()); mmput(mm); } } void exit_mm(struct task_struct *tsk) { __exit_mm(tsk); } /* * Send signals to all our closest relatives so that they know * to properly mourn us.. */ static void exit_notify(void) { struct task_struct * p, *t; forget_original_parent(current); /* * Check to see if any process groups have become orphaned * as a result of our exiting, and if they have any stopped * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) * * Case i: Our father is in a different pgrp than we are * and we were the only connection outside, so our pgrp * is about to become orphaned. */ t = current->p_pptr; if ((t->pgrp != current->pgrp) && (t->session == current->session) && will_become_orphaned_pgrp(current->pgrp, current) && has_stopped_jobs(current->pgrp)) { kill_pg(current->pgrp,SIGHUP,1); kill_pg(current->pgrp,SIGCONT,1); } /* Let father know we died * * Thread signals are configurable, but you aren't going to use * that to send signals to arbitary processes. * That stops right now. * * If the parent exec id doesn't match the exec id we saved * when we started then we know the parent has changed security * domain. * * If our self_exec id doesn't match our parent_exec_id then * we have changed execution domain as these two values started * the same after a fork. * */ if(current->exit_signal != SIGCHLD && ( current->parent_exec_id != t->self_exec_id || current->self_exec_id != current->parent_exec_id) && !capable(CAP_KILL)) current->exit_signal = SIGCHLD; /* * This loop does two things: * * A. Make init inherit all the child processes * B. Check to see if any process groups have become orphaned * as a result of our exiting, and if they have any stopped * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) */ write_lock_irq(&tasklist_lock); current->state = TASK_ZOMBIE; do_notify_parent(current, current->exit_signal); while (current->p_cptr != NULL) { p = current->p_cptr; current->p_cptr = p->p_osptr; p->p_ysptr = NULL; p->ptrace = 0; p->p_pptr = p->p_opptr; p->p_osptr = p->p_pptr->p_cptr; if (p->p_osptr) p->p_osptr->p_ysptr = p; p->p_pptr->p_cptr = p; if (p->state == TASK_ZOMBIE) do_notify_parent(p, p->exit_signal); /* * process group orphan check * Case ii: Our child is in a different pgrp * than we are, and it was the only connection * outside, so the child pgrp is now orphaned. */ if ((p->pgrp != current->pgrp) && (p->session == current->session)) { int pgrp = p->pgrp; write_unlock_irq(&tasklist_lock); if (is_orphaned_pgrp(pgrp) && has_stopped_jobs(pgrp)) { kill_pg(pgrp,SIGHUP,1); kill_pg(pgrp,SIGCONT,1); } write_lock_irq(&tasklist_lock); } } write_unlock_irq(&tasklist_lock); } NORET_TYPE void do_exit(long code) { struct task_struct *tsk = current; if (in_interrupt()) panic("Aiee, killing interrupt handler!"); if (!tsk->pid) panic("Attempted to kill the idle task!"); if (tsk->pid == 1) panic("Attempted to kill init!"); tsk->flags |= PF_EXITING; del_timer_sync(&tsk->real_timer); fake_volatile: #ifdef CONFIG_BSD_PROCESS_ACCT acct_process(code); #endif __exit_mm(tsk); lock_kernel(); sem_exit(); __exit_files(tsk); __exit_fs(tsk); exit_sighand(tsk); exit_thread(); if (current->leader) disassociate_ctty(1); put_exec_domain(tsk->exec_domain); if (tsk->binfmt && tsk->binfmt->module) __MOD_DEC_USE_COUNT(tsk->binfmt->module); tsk->exit_code = code; exit_notify(); schedule(); BUG(); /* * In order to get rid of the "volatile function does return" message * I did this little loop that confuses gcc to think do_exit really * is volatile. In fact it's schedule() that is volatile in some * circumstances: when current->state = ZOMBIE, schedule() never * returns. * * In fact the natural way to do all this is to have the label and the * goto right after each other, but I put the fake_volatile label at * the start of the function just in case something /really/ bad * happens, and the schedule returns. This way we can try again. I'm * not paranoid: it's just that everybody is out to get me. */ goto fake_volatile; } NORET_TYPE void up_and_exit(struct semaphore *sem, long code) { if (sem) up(sem); do_exit(code); } asmlinkage long sys_exit(int error_code) { do_exit((error_code&0xff)<<8); } asmlinkage long sys_wait4(pid_t pid,unsigned int * stat_addr, int options, struct rusage * ru) { int flag, retval; DECLARE_WAITQUEUE(wait, current); struct task_struct *tsk; if (options & ~(WNOHANG|WUNTRACED|__WNOTHREAD|__WCLONE|__WALL)) return -EINVAL; add_wait_queue(¤t->wait_chldexit,&wait); repeat: flag = 0; current->state = TASK_INTERRUPTIBLE; read_lock(&tasklist_lock); tsk = current; do { struct task_struct *p; for (p = tsk->p_cptr ; p ; p = p->p_osptr) { if (pid>0) { if (p->pid != pid) continue; } else if (!pid) { if (p->pgrp != current->pgrp) continue; } else if (pid != -1) { if (p->pgrp != -pid) continue; } /* Wait for all children (clone and not) if __WALL is set; * otherwise, wait for clone children *only* if __WCLONE is * set; otherwise, wait for non-clone children *only*. (Note: * A "clone" child here is one that reports to its parent * using a signal other than SIGCHLD.) */ if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0)) && !(options & __WALL)) continue; flag = 1; switch (p->state) { case TASK_STOPPED: if (!p->exit_code) continue; if (!(options & WUNTRACED) && !(p->ptrace & PT_PTRACED)) continue; read_unlock(&tasklist_lock); retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; if (!retval && stat_addr) retval = put_user((p->exit_code << 8) | 0x7f, stat_addr); if (!retval) { p->exit_code = 0; retval = p->pid; } goto end_wait4; case TASK_ZOMBIE: current->times.tms_cutime += p->times.tms_utime + p->times.tms_cutime; current->times.tms_cstime += p->times.tms_stime + p->times.tms_cstime; read_unlock(&tasklist_lock); retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; if (!retval && stat_addr) retval = put_user(p->exit_code, stat_addr); if (retval) goto end_wait4; retval = p->pid; if (p->p_opptr != p->p_pptr) { write_lock_irq(&tasklist_lock); REMOVE_LINKS(p); p->p_pptr = p->p_opptr; SET_LINKS(p); do_notify_parent(p, SIGCHLD); write_unlock_irq(&tasklist_lock); } else release_task(p); goto end_wait4; default: continue; } } if (options & __WNOTHREAD) break; tsk = next_thread(tsk); } while (tsk != current); read_unlock(&tasklist_lock); if (flag) { retval = 0; if (options & WNOHANG) goto end_wait4; retval = -ERESTARTSYS; if (signal_pending(current)) goto end_wait4; schedule(); goto repeat; } retval = -ECHILD; end_wait4: current->state = TASK_RUNNING; remove_wait_queue(¤t->wait_chldexit,&wait); return retval; } #if !defined(__alpha__) && !defined(__ia64__) /* * sys_waitpid() remains for compatibility. waitpid() should be * implemented by calling sys_wait4() from libc.a. */ asmlinkage long sys_waitpid(pid_t pid,unsigned int * stat_addr, int options) { return sys_wait4(pid, stat_addr, options, NULL); } #endif