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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>
#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);
#ifdef CONFIG_HARDEN_SHM
extern void shm_exit (void);
#endif
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 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++;
/* Make sure we're not reparenting to ourselves */
if (p == reaper)
p->p_opptr = child_reaper;
else
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();
#ifdef CONFIG_HARDEN_SHM
shm_exit();
#endif
__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 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(¤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
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