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/*

 *  linux/kernel/exit.c

 *

 *  Copyright (C) 1991, 1992  Linus Torvalds

 */

#include <linux/config.h>

#include <linux/slab.h>

#include <linux/interrupt.h>

#include <linux/smp_lock.h>

#include <linux/module.h>

#include <linux/completion.h>

#include <linux/personality.h>

#include <linux/tty.h>

#include <linux/namespace.h>

#ifdef CONFIG_BSD_PROCESS_ACCT

#include <linux/acct.h>

#endif

#include <asm/uaccess.h>

#include <asm/pgtable.h>

#include <asm/mmu_context.h>

extern void sem_exit (void);

extern struct task_struct *child_reaper;

int getrusage(struct task_struct *, int, struct rusage *);

static 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 (!task_has_cpu(p))

                                break;

                        task_unlock(p);

                        do {

                                cpu_relax();

                                barrier();

                        } while (task_has_cpu(p));

                }

                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;

                p->pid = 0;

                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 thread

 * 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;

        read_lock(&tasklist_lock);

        for_each_task(p) {

                if (p->p_opptr == father) {

                        /* We dont want people slaying init */

                        p->exit_signal = SIGCHLD;

                        p->self_exec_id++;

                        /* Make sure we're not reparenting to ourselves */

                        p->p_opptr = child_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);

                BUG_ON(mm != tsk->active_mm);

                /* 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_namespace(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 complete_and_exit(struct completion *comp, long code)

{

        if (comp)

                complete(comp);

        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(&current->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(&current->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