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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/kernel/exit.c

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39 KiB
C
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/*
* linux/kernel/exit.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/config.h>
#include <linux/mm.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>
#include <linux/key.h>
#include <linux/security.h>
#include <linux/cpu.h>
#include <linux/acct.h>
#include <linux/file.h>
#include <linux/binfmts.h>
#include <linux/ptrace.h>
#include <linux/profile.h>
#include <linux/mount.h>
#include <linux/proc_fs.h>
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/syscalls.h>
#include <linux/signal.h>
#include <asm/uaccess.h>
#include <asm/unistd.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 __user *);
static void exit_mm(struct task_struct * tsk);
static void __unhash_process(struct task_struct *p)
{
nr_threads--;
detach_pid(p, PIDTYPE_PID);
detach_pid(p, PIDTYPE_TGID);
if (thread_group_leader(p)) {
detach_pid(p, PIDTYPE_PGID);
detach_pid(p, PIDTYPE_SID);
if (p->pid)
__get_cpu_var(process_counts)--;
}
REMOVE_LINKS(p);
}
void release_task(struct task_struct * p)
{
int zap_leader;
task_t *leader;
struct dentry *proc_dentry;
repeat:
atomic_dec(&p->user->processes);
spin_lock(&p->proc_lock);
proc_dentry = proc_pid_unhash(p);
write_lock_irq(&tasklist_lock);
if (unlikely(p->ptrace))
__ptrace_unlink(p);
BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
__exit_signal(p);
__exit_sighand(p);
/*
* Note that the fastpath in sys_times depends on __exit_signal having
* updated the counters before a task is removed from the tasklist of
* the process by __unhash_process.
*/
__unhash_process(p);
/*
* If we are the last non-leader member of the thread
* group, and the leader is zombie, then notify the
* group leader's parent process. (if it wants notification.)
*/
zap_leader = 0;
leader = p->group_leader;
if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
BUG_ON(leader->exit_signal == -1);
do_notify_parent(leader, leader->exit_signal);
/*
* If we were the last child thread and the leader has
* exited already, and the leader's parent ignores SIGCHLD,
* then we are the one who should release the leader.
*
* do_notify_parent() will have marked it self-reaping in
* that case.
*/
zap_leader = (leader->exit_signal == -1);
}
sched_exit(p);
write_unlock_irq(&tasklist_lock);
spin_unlock(&p->proc_lock);
proc_pid_flush(proc_dentry);
release_thread(p);
put_task_struct(p);
p = leader;
if (unlikely(zap_leader))
goto repeat;
}
/* we are using it only for SMP init */
void unhash_process(struct task_struct *p)
{
struct dentry *proc_dentry;
spin_lock(&p->proc_lock);
proc_dentry = proc_pid_unhash(p);
write_lock_irq(&tasklist_lock);
__unhash_process(p);
write_unlock_irq(&tasklist_lock);
spin_unlock(&p->proc_lock);
proc_pid_flush(proc_dentry);
}
/*
* 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 sid = -1;
read_lock(&tasklist_lock);
do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
if (p->signal->session > 0) {
sid = p->signal->session;
goto out;
}
} while_each_task_pid(pgrp, PIDTYPE_PGID, p);
p = find_task_by_pid(pgrp);
if (p)
sid = p->signal->session;
out:
read_unlock(&tasklist_lock);
return sid;
}
/*
* 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, task_t *ignored_task)
{
struct task_struct *p;
int ret = 1;
do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
if (p == ignored_task
|| p->exit_state
|| p->real_parent->pid == 1)
continue;
if (process_group(p->real_parent) != pgrp
&& p->real_parent->signal->session == p->signal->session) {
ret = 0;
break;
}
} while_each_task_pid(pgrp, PIDTYPE_PGID, p);
return ret; /* (sighing) "Often!" */
}
int is_orphaned_pgrp(int pgrp)
{
int retval;
read_lock(&tasklist_lock);
retval = will_become_orphaned_pgrp(pgrp, NULL);
read_unlock(&tasklist_lock);
return retval;
}
static inline int has_stopped_jobs(int pgrp)
{
int retval = 0;
struct task_struct *p;
do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
if (p->state != TASK_STOPPED)
continue;
/* If p is stopped by a debugger on a signal that won't
stop it, then don't count p as stopped. This isn't
perfect but it's a good approximation. */
if (unlikely (p->ptrace)
&& p->exit_code != SIGSTOP
&& p->exit_code != SIGTSTP
&& p->exit_code != SIGTTOU
&& p->exit_code != SIGTTIN)
continue;
retval = 1;
break;
} while_each_task_pid(pgrp, PIDTYPE_PGID, p);
return retval;
}
/**
* reparent_to_init - Reparent the calling kernel thread to the init task.
*
* If a kernel thread is launched as a result of a system call, or if
* it ever exits, it should generally reparent itself to init so that
* it is correctly cleaned up on exit.
*
* The various task state such as scheduling policy and priority may have
* been inherited from a user process, so we reset them to sane values here.
*
* NOTE that reparent_to_init() gives the caller full capabilities.
*/
static inline void reparent_to_init(void)
{
write_lock_irq(&tasklist_lock);
ptrace_unlink(current);
/* Reparent to init */
REMOVE_LINKS(current);
current->parent = child_reaper;
current->real_parent = child_reaper;
SET_LINKS(current);
/* Set the exit signal to SIGCHLD so we signal init on exit */
current->exit_signal = SIGCHLD;
if ((current->policy == SCHED_NORMAL) && (task_nice(current) < 0))
set_user_nice(current, 0);
/* cpus_allowed? */
/* rt_priority? */
/* signals? */
security_task_reparent_to_init(current);
memcpy(current->signal->rlim, init_task.signal->rlim,
sizeof(current->signal->rlim));
atomic_inc(&(INIT_USER->__count));
write_unlock_irq(&tasklist_lock);
switch_uid(INIT_USER);
}
void __set_special_pids(pid_t session, pid_t pgrp)
{
struct task_struct *curr = current;
if (curr->signal->session != session) {
detach_pid(curr, PIDTYPE_SID);
curr->signal->session = session;
attach_pid(curr, PIDTYPE_SID, session);
}
if (process_group(curr) != pgrp) {
detach_pid(curr, PIDTYPE_PGID);
curr->signal->pgrp = pgrp;
attach_pid(curr, PIDTYPE_PGID, pgrp);
}
}
void set_special_pids(pid_t session, pid_t pgrp)
{
write_lock_irq(&tasklist_lock);
__set_special_pids(session, pgrp);
write_unlock_irq(&tasklist_lock);
}
/*
* Let kernel threads use this to say that they
* allow a certain signal (since daemonize() will
* have disabled all of them by default).
*/
int allow_signal(int sig)
{
if (!valid_signal(sig) || sig < 1)
return -EINVAL;
spin_lock_irq(&current->sighand->siglock);
sigdelset(&current->blocked, sig);
if (!current->mm) {
/* Kernel threads handle their own signals.
Let the signal code know it'll be handled, so
that they don't get converted to SIGKILL or
just silently dropped */
current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
}
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
return 0;
}
EXPORT_SYMBOL(allow_signal);
int disallow_signal(int sig)
{
if (!valid_signal(sig) || sig < 1)
return -EINVAL;
spin_lock_irq(&current->sighand->siglock);
sigaddset(&current->blocked, sig);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
return 0;
}
EXPORT_SYMBOL(disallow_signal);
/*
* Put all the gunge required to become a kernel thread without
* attached user resources in one place where it belongs.
*/
void daemonize(const char *name, ...)
{
va_list args;
struct fs_struct *fs;
sigset_t blocked;
va_start(args, name);
vsnprintf(current->comm, sizeof(current->comm), name, args);
va_end(args);
/*
* If we were started as result of loading a module, close all of the
* user space pages. We don't need them, and if we didn't close them
* they would be locked into memory.
*/
exit_mm(current);
set_special_pids(1, 1);
down(&tty_sem);
current->signal->tty = NULL;
up(&tty_sem);
/* Block and flush all signals */
sigfillset(&blocked);
sigprocmask(SIG_BLOCK, &blocked, NULL);
flush_signals(current);
/* Become as one with the init task */
exit_fs(current); /* current->fs->count--; */
fs = init_task.fs;
current->fs = fs;
atomic_inc(&fs->count);
exit_files(current);
current->files = init_task.files;
atomic_inc(&current->files->count);
reparent_to_init();
}
EXPORT_SYMBOL(daemonize);
static inline void close_files(struct files_struct * files)
{
int i, j;
struct fdtable *fdt;
j = 0;
fdt = files_fdtable(files);
for (;;) {
unsigned long set;
i = j * __NFDBITS;
if (i >= fdt->max_fdset || i >= fdt->max_fds)
break;
set = fdt->open_fds->fds_bits[j++];
while (set) {
if (set & 1) {
struct file * file = xchg(&fdt->fd[i], NULL);
if (file)
filp_close(file, files);
}
i++;
set >>= 1;
}
}
}
struct files_struct *get_files_struct(struct task_struct *task)
{
struct files_struct *files;
task_lock(task);
files = task->files;
if (files)
atomic_inc(&files->count);
task_unlock(task);
return files;
}
void fastcall put_files_struct(struct files_struct *files)
{
struct fdtable *fdt;
if (atomic_dec_and_test(&files->count)) {
close_files(files);
/*
* Free the fd and fdset arrays if we expanded them.
* If the fdtable was embedded, pass files for freeing
* at the end of the RCU grace period. Otherwise,
* you can free files immediately.
*/
fdt = files_fdtable(files);
if (fdt == &files->fdtab)
fdt->free_files = files;
else
kmem_cache_free(files_cachep, files);
free_fdtable(fdt);
}
}
EXPORT_SYMBOL(put_files_struct);
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);
}
EXPORT_SYMBOL_GPL(exit_fs);
/*
* Turn us into a lazy TLB process if we
* aren't already..
*/
static void exit_mm(struct task_struct * tsk)
{
struct mm_struct *mm = tsk->mm;
mm_release(tsk, mm);
if (!mm)
return;
/*
* Serialize with any possible pending coredump.
* We must hold mmap_sem around checking core_waiters
* and clearing tsk->mm. The core-inducing thread
* will increment core_waiters for each thread in the
* group with ->mm != NULL.
*/
down_read(&mm->mmap_sem);
if (mm->core_waiters) {
up_read(&mm->mmap_sem);
down_write(&mm->mmap_sem);
if (!--mm->core_waiters)
complete(mm->core_startup_done);
up_write(&mm->mmap_sem);
wait_for_completion(&mm->core_done);
down_read(&mm->mmap_sem);
}
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;
up_read(&mm->mmap_sem);
enter_lazy_tlb(mm, current);
task_unlock(tsk);
mmput(mm);
}
static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_reaper)
{
/*
* Make sure we're not reparenting to ourselves and that
* the parent is not a zombie.
*/
BUG_ON(p == reaper || reaper->exit_state >= EXIT_ZOMBIE);
p->real_parent = reaper;
}
static inline void reparent_thread(task_t *p, task_t *father, int traced)
{
/* We don't want people slaying init. */
if (p->exit_signal != -1)
p->exit_signal = SIGCHLD;
if (p->pdeath_signal)
/* We already hold the tasklist_lock here. */
group_send_sig_info(p->pdeath_signal, (void *) 0, p);
/* Move the child from its dying parent to the new one. */
if (unlikely(traced)) {
/* Preserve ptrace links if someone else is tracing this child. */
list_del_init(&p->ptrace_list);
if (p->parent != p->real_parent)
list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
} else {
/* If this child is being traced, then we're the one tracing it
* anyway, so let go of it.
*/
p->ptrace = 0;
list_del_init(&p->sibling);
p->parent = p->real_parent;
list_add_tail(&p->sibling, &p->parent->children);
/* If we'd notified the old parent about this child's death,
* also notify the new parent.
*/
if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
thread_group_empty(p))
do_notify_parent(p, p->exit_signal);
else if (p->state == TASK_TRACED) {
/*
* If it was at a trace stop, turn it into
* a normal stop since it's no longer being
* traced.
*/
ptrace_untrace(p);
}
}
/*
* 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 ((process_group(p) != process_group(father)) &&
(p->signal->session == father->signal->session)) {
int pgrp = process_group(p);
if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
__kill_pg_info(SIGHUP, (void *)1, pgrp);
__kill_pg_info(SIGCONT, (void *)1, pgrp);
}
}
}
/*
* 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 list_head *to_release)
{
struct task_struct *p, *reaper = father;
struct list_head *_p, *_n;
do {
reaper = next_thread(reaper);
if (reaper == father) {
reaper = child_reaper;
break;
}
} while (reaper->exit_state);
/*
* There are only two places where our children can be:
*
* - in our child list
* - in our ptraced child list
*
* Search them and reparent children.
*/
list_for_each_safe(_p, _n, &father->children) {
int ptrace;
p = list_entry(_p,struct task_struct,sibling);
ptrace = p->ptrace;
/* if father isn't the real parent, then ptrace must be enabled */
BUG_ON(father != p->real_parent && !ptrace);
if (father == p->real_parent) {
/* reparent with a reaper, real father it's us */
choose_new_parent(p, reaper, child_reaper);
reparent_thread(p, father, 0);
} else {
/* reparent ptraced task to its real parent */
__ptrace_unlink (p);
if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
thread_group_empty(p))
do_notify_parent(p, p->exit_signal);
}
/*
* if the ptraced child is a zombie with exit_signal == -1
* we must collect it before we exit, or it will remain
* zombie forever since we prevented it from self-reap itself
* while it was being traced by us, to be able to see it in wait4.
*/
if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
list_add(&p->ptrace_list, to_release);
}
list_for_each_safe(_p, _n, &father->ptrace_children) {
p = list_entry(_p,struct task_struct,ptrace_list);
choose_new_parent(p, reaper, child_reaper);
reparent_thread(p, father, 1);
}
}
/*
* Send signals to all our closest relatives so that they know
* to properly mourn us..
*/
static void exit_notify(struct task_struct *tsk)
{
int state;
struct task_struct *t;
struct list_head ptrace_dead, *_p, *_n;
if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
&& !thread_group_empty(tsk)) {
/*
* This occurs when there was a race between our exit
* syscall and a group signal choosing us as the one to
* wake up. It could be that we are the only thread
* alerted to check for pending signals, but another thread
* should be woken now to take the signal since we will not.
* Now we'll wake all the threads in the group just to make
* sure someone gets all the pending signals.
*/
read_lock(&tasklist_lock);
spin_lock_irq(&tsk->sighand->siglock);
for (t = next_thread(tsk); t != tsk; t = next_thread(t))
if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
recalc_sigpending_tsk(t);
if (signal_pending(t))
signal_wake_up(t, 0);
}
spin_unlock_irq(&tsk->sighand->siglock);
read_unlock(&tasklist_lock);
}
write_lock_irq(&tasklist_lock);
/*
* This 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)
*/
INIT_LIST_HEAD(&ptrace_dead);
forget_original_parent(tsk, &ptrace_dead);
BUG_ON(!list_empty(&tsk->children));
BUG_ON(!list_empty(&tsk->ptrace_children));
/*
* 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 = tsk->real_parent;
if ((process_group(t) != process_group(tsk)) &&
(t->signal->session == tsk->signal->session) &&
will_become_orphaned_pgrp(process_group(tsk), tsk) &&
has_stopped_jobs(process_group(tsk))) {
__kill_pg_info(SIGHUP, (void *)1, process_group(tsk));
__kill_pg_info(SIGCONT, (void *)1, process_group(tsk));
}
/* 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 (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
( tsk->parent_exec_id != t->self_exec_id ||
tsk->self_exec_id != tsk->parent_exec_id)
&& !capable(CAP_KILL))
tsk->exit_signal = SIGCHLD;
/* If something other than our normal parent is ptracing us, then
* send it a SIGCHLD instead of honoring exit_signal. exit_signal
* only has special meaning to our real parent.
*/
if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
do_notify_parent(tsk, signal);
} else if (tsk->ptrace) {
do_notify_parent(tsk, SIGCHLD);
}
state = EXIT_ZOMBIE;
if (tsk->exit_signal == -1 &&
(likely(tsk->ptrace == 0) ||
unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
state = EXIT_DEAD;
tsk->exit_state = state;
write_unlock_irq(&tasklist_lock);
list_for_each_safe(_p, _n, &ptrace_dead) {
list_del_init(_p);
t = list_entry(_p,struct task_struct,ptrace_list);
release_task(t);
}
/* If the process is dead, release it - nobody will wait for it */
if (state == EXIT_DEAD)
release_task(tsk);
/* PF_DEAD causes final put_task_struct after we schedule. */
preempt_disable();
tsk->flags |= PF_DEAD;
}
fastcall NORET_TYPE void do_exit(long code)
{
struct task_struct *tsk = current;
int group_dead;
profile_task_exit(tsk);
WARN_ON(atomic_read(&tsk->fs_excl));
if (unlikely(in_interrupt()))
panic("Aiee, killing interrupt handler!");
if (unlikely(!tsk->pid))
panic("Attempted to kill the idle task!");
if (unlikely(tsk->pid == 1))
panic("Attempted to kill init!");
if (tsk->io_context)
exit_io_context();
if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
current->ptrace_message = code;
ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
}
/*
* We're taking recursive faults here in do_exit. Safest is to just
* leave this task alone and wait for reboot.
*/
if (unlikely(tsk->flags & PF_EXITING)) {
printk(KERN_ALERT
"Fixing recursive fault but reboot is needed!\n");
set_current_state(TASK_UNINTERRUPTIBLE);
schedule();
}
tsk->flags |= PF_EXITING;
/*
* Make sure we don't try to process any timer firings
* while we are already exiting.
*/
tsk->it_virt_expires = cputime_zero;
tsk->it_prof_expires = cputime_zero;
tsk->it_sched_expires = 0;
if (unlikely(in_atomic()))
printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
current->comm, current->pid,
preempt_count());
acct_update_integrals(tsk);
update_mem_hiwater(tsk);
group_dead = atomic_dec_and_test(&tsk->signal->live);
if (group_dead) {
del_timer_sync(&tsk->signal->real_timer);
acct_process(code);
}
exit_mm(tsk);
exit_sem(tsk);
__exit_files(tsk);
__exit_fs(tsk);
exit_namespace(tsk);
exit_thread();
cpuset_exit(tsk);
exit_keys(tsk);
if (group_dead && tsk->signal->leader)
disassociate_ctty(1);
module_put(tsk->thread_info->exec_domain->module);
if (tsk->binfmt)
module_put(tsk->binfmt->module);
tsk->exit_code = code;
exit_notify(tsk);
#ifdef CONFIG_NUMA
mpol_free(tsk->mempolicy);
tsk->mempolicy = NULL;
#endif
BUG_ON(!(current->flags & PF_DEAD));
schedule();
BUG();
/* Avoid "noreturn function does return". */
for (;;) ;
}
EXPORT_SYMBOL_GPL(do_exit);
NORET_TYPE void complete_and_exit(struct completion *comp, long code)
{
if (comp)
complete(comp);
do_exit(code);
}
EXPORT_SYMBOL(complete_and_exit);
asmlinkage long sys_exit(int error_code)
{
do_exit((error_code&0xff)<<8);
}
task_t fastcall *next_thread(const task_t *p)
{
return pid_task(p->pids[PIDTYPE_TGID].pid_list.next, PIDTYPE_TGID);
}
EXPORT_SYMBOL(next_thread);
/*
* Take down every thread in the group. This is called by fatal signals
* as well as by sys_exit_group (below).
*/
NORET_TYPE void
do_group_exit(int exit_code)
{
BUG_ON(exit_code & 0x80); /* core dumps don't get here */
if (current->signal->flags & SIGNAL_GROUP_EXIT)
exit_code = current->signal->group_exit_code;
else if (!thread_group_empty(current)) {
struct signal_struct *const sig = current->signal;
struct sighand_struct *const sighand = current->sighand;
read_lock(&tasklist_lock);
spin_lock_irq(&sighand->siglock);
if (sig->flags & SIGNAL_GROUP_EXIT)
/* Another thread got here before we took the lock. */
exit_code = sig->group_exit_code;
else {
sig->flags = SIGNAL_GROUP_EXIT;
sig->group_exit_code = exit_code;
zap_other_threads(current);
}
spin_unlock_irq(&sighand->siglock);
read_unlock(&tasklist_lock);
}
do_exit(exit_code);
/* NOTREACHED */
}
/*
* this kills every thread in the thread group. Note that any externally
* wait4()-ing process will get the correct exit code - even if this
* thread is not the thread group leader.
*/
asmlinkage void sys_exit_group(int error_code)
{
do_group_exit((error_code & 0xff) << 8);
}
static int eligible_child(pid_t pid, int options, task_t *p)
{
if (pid > 0) {
if (p->pid != pid)
return 0;
} else if (!pid) {
if (process_group(p) != process_group(current))
return 0;
} else if (pid != -1) {
if (process_group(p) != -pid)
return 0;
}
/*
* Do not consider detached threads that are
* not ptraced:
*/
if (p->exit_signal == -1 && !p->ptrace)
return 0;
/* 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))
return 0;
/*
* Do not consider thread group leaders that are
* in a non-empty thread group:
*/
if (current->tgid != p->tgid && delay_group_leader(p))
return 2;
if (security_task_wait(p))
return 0;
return 1;
}
static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid,
int why, int status,
struct siginfo __user *infop,
struct rusage __user *rusagep)
{
int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
put_task_struct(p);
if (!retval)
retval = put_user(SIGCHLD, &infop->si_signo);
if (!retval)
retval = put_user(0, &infop->si_errno);
if (!retval)
retval = put_user((short)why, &infop->si_code);
if (!retval)
retval = put_user(pid, &infop->si_pid);
if (!retval)
retval = put_user(uid, &infop->si_uid);
if (!retval)
retval = put_user(status, &infop->si_status);
if (!retval)
retval = pid;
return retval;
}
/*
* Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
* read_lock(&tasklist_lock) on entry. If we return zero, we still hold
* the lock and this task is uninteresting. If we return nonzero, we have
* released the lock and the system call should return.
*/
static int wait_task_zombie(task_t *p, int noreap,
struct siginfo __user *infop,
int __user *stat_addr, struct rusage __user *ru)
{
unsigned long state;
int retval;
int status;
if (unlikely(noreap)) {
pid_t pid = p->pid;
uid_t uid = p->uid;
int exit_code = p->exit_code;
int why, status;
if (unlikely(p->exit_state != EXIT_ZOMBIE))
return 0;
if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
return 0;
get_task_struct(p);
read_unlock(&tasklist_lock);
if ((exit_code & 0x7f) == 0) {
why = CLD_EXITED;
status = exit_code >> 8;
} else {
why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
status = exit_code & 0x7f;
}
return wait_noreap_copyout(p, pid, uid, why,
status, infop, ru);
}
/*
* Try to move the task's state to DEAD
* only one thread is allowed to do this:
*/
state = xchg(&p->exit_state, EXIT_DEAD);
if (state != EXIT_ZOMBIE) {
BUG_ON(state != EXIT_DEAD);
return 0;
}
if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
/*
* This can only happen in a race with a ptraced thread
* dying on another processor.
*/
return 0;
}
if (likely(p->real_parent == p->parent) && likely(p->signal)) {
/*
* The resource counters for the group leader are in its
* own task_struct. Those for dead threads in the group
* are in its signal_struct, as are those for the child
* processes it has previously reaped. All these
* accumulate in the parent's signal_struct c* fields.
*
* We don't bother to take a lock here to protect these
* p->signal fields, because they are only touched by
* __exit_signal, which runs with tasklist_lock
* write-locked anyway, and so is excluded here. We do
* need to protect the access to p->parent->signal fields,
* as other threads in the parent group can be right
* here reaping other children at the same time.
*/
spin_lock_irq(&p->parent->sighand->siglock);
p->parent->signal->cutime =
cputime_add(p->parent->signal->cutime,
cputime_add(p->utime,
cputime_add(p->signal->utime,
p->signal->cutime)));
p->parent->signal->cstime =
cputime_add(p->parent->signal->cstime,
cputime_add(p->stime,
cputime_add(p->signal->stime,
p->signal->cstime)));
p->parent->signal->cmin_flt +=
p->min_flt + p->signal->min_flt + p->signal->cmin_flt;
p->parent->signal->cmaj_flt +=
p->maj_flt + p->signal->maj_flt + p->signal->cmaj_flt;
p->parent->signal->cnvcsw +=
p->nvcsw + p->signal->nvcsw + p->signal->cnvcsw;
p->parent->signal->cnivcsw +=
p->nivcsw + p->signal->nivcsw + p->signal->cnivcsw;
spin_unlock_irq(&p->parent->sighand->siglock);
}
/*
* Now we are sure this task is interesting, and no other
* thread can reap it because we set its state to EXIT_DEAD.
*/
read_unlock(&tasklist_lock);
retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
status = (p->signal->flags & SIGNAL_GROUP_EXIT)
? p->signal->group_exit_code : p->exit_code;
if (!retval && stat_addr)
retval = put_user(status, stat_addr);
if (!retval && infop)
retval = put_user(SIGCHLD, &infop->si_signo);
if (!retval && infop)
retval = put_user(0, &infop->si_errno);
if (!retval && infop) {
int why;
if ((status & 0x7f) == 0) {
why = CLD_EXITED;
status >>= 8;
} else {
why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
status &= 0x7f;
}
retval = put_user((short)why, &infop->si_code);
if (!retval)
retval = put_user(status, &infop->si_status);
}
if (!retval && infop)
retval = put_user(p->pid, &infop->si_pid);
if (!retval && infop)
retval = put_user(p->uid, &infop->si_uid);
if (retval) {
// TODO: is this safe?
p->exit_state = EXIT_ZOMBIE;
return retval;
}
retval = p->pid;
if (p->real_parent != p->parent) {
write_lock_irq(&tasklist_lock);
/* Double-check with lock held. */
if (p->real_parent != p->parent) {
__ptrace_unlink(p);
// TODO: is this safe?
p->exit_state = EXIT_ZOMBIE;
/*
* If this is not a detached task, notify the parent.
* If it's still not detached after that, don't release
* it now.
*/
if (p->exit_signal != -1) {
do_notify_parent(p, p->exit_signal);
if (p->exit_signal != -1)
p = NULL;
}
}
write_unlock_irq(&tasklist_lock);
}
if (p != NULL)
release_task(p);
BUG_ON(!retval);
return retval;
}
/*
* Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
* read_lock(&tasklist_lock) on entry. If we return zero, we still hold
* the lock and this task is uninteresting. If we return nonzero, we have
* released the lock and the system call should return.
*/
static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap,
struct siginfo __user *infop,
int __user *stat_addr, struct rusage __user *ru)
{
int retval, exit_code;
if (!p->exit_code)
return 0;
if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
p->signal && p->signal->group_stop_count > 0)
/*
* A group stop is in progress and this is the group leader.
* We won't report until all threads have stopped.
*/
return 0;
/*
* Now we are pretty sure this task is interesting.
* Make sure it doesn't get reaped out from under us while we
* give up the lock and then examine it below. We don't want to
* keep holding onto the tasklist_lock while we call getrusage and
* possibly take page faults for user memory.
*/
get_task_struct(p);
read_unlock(&tasklist_lock);
if (unlikely(noreap)) {
pid_t pid = p->pid;
uid_t uid = p->uid;
int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
exit_code = p->exit_code;
if (unlikely(!exit_code) ||
unlikely(p->state > TASK_STOPPED))
goto bail_ref;
return wait_noreap_copyout(p, pid, uid,
why, (exit_code << 8) | 0x7f,
infop, ru);
}
write_lock_irq(&tasklist_lock);
/*
* This uses xchg to be atomic with the thread resuming and setting
* it. It must also be done with the write lock held to prevent a
* race with the EXIT_ZOMBIE case.
*/
exit_code = xchg(&p->exit_code, 0);
if (unlikely(p->exit_state)) {
/*
* The task resumed and then died. Let the next iteration
* catch it in EXIT_ZOMBIE. Note that exit_code might
* already be zero here if it resumed and did _exit(0).
* The task itself is dead and won't touch exit_code again;
* other processors in this function are locked out.
*/
p->exit_code = exit_code;
exit_code = 0;
}
if (unlikely(exit_code == 0)) {
/*
* Another thread in this function got to it first, or it
* resumed, or it resumed and then died.
*/
write_unlock_irq(&tasklist_lock);
bail_ref:
put_task_struct(p);
/*
* We are returning to the wait loop without having successfully
* removed the process and having released the lock. We cannot
* continue, since the "p" task pointer is potentially stale.
*
* Return -EAGAIN, and do_wait() will restart the loop from the
* beginning. Do _not_ re-acquire the lock.
*/
return -EAGAIN;
}
/* move to end of parent's list to avoid starvation */
remove_parent(p);
add_parent(p, p->parent);
write_unlock_irq(&tasklist_lock);
retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
if (!retval && stat_addr)
retval = put_user((exit_code << 8) | 0x7f, stat_addr);
if (!retval && infop)
retval = put_user(SIGCHLD, &infop->si_signo);
if (!retval && infop)
retval = put_user(0, &infop->si_errno);
if (!retval && infop)
retval = put_user((short)((p->ptrace & PT_PTRACED)
? CLD_TRAPPED : CLD_STOPPED),
&infop->si_code);
if (!retval && infop)
retval = put_user(exit_code, &infop->si_status);
if (!retval && infop)
retval = put_user(p->pid, &infop->si_pid);
if (!retval && infop)
retval = put_user(p->uid, &infop->si_uid);
if (!retval)
retval = p->pid;
put_task_struct(p);
BUG_ON(!retval);
return retval;
}
/*
* Handle do_wait work for one task in a live, non-stopped state.
* read_lock(&tasklist_lock) on entry. If we return zero, we still hold
* the lock and this task is uninteresting. If we return nonzero, we have
* released the lock and the system call should return.
*/
static int wait_task_continued(task_t *p, int noreap,
struct siginfo __user *infop,
int __user *stat_addr, struct rusage __user *ru)
{
int retval;
pid_t pid;
uid_t uid;
if (unlikely(!p->signal))
return 0;
if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
return 0;
spin_lock_irq(&p->sighand->siglock);
/* Re-check with the lock held. */
if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
spin_unlock_irq(&p->sighand->siglock);
return 0;
}
if (!noreap)
p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
spin_unlock_irq(&p->sighand->siglock);
pid = p->pid;
uid = p->uid;
get_task_struct(p);
read_unlock(&tasklist_lock);
if (!infop) {
retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
put_task_struct(p);
if (!retval && stat_addr)
retval = put_user(0xffff, stat_addr);
if (!retval)
retval = p->pid;
} else {
retval = wait_noreap_copyout(p, pid, uid,
CLD_CONTINUED, SIGCONT,
infop, ru);
BUG_ON(retval == 0);
}
return retval;
}
static inline int my_ptrace_child(struct task_struct *p)
{
if (!(p->ptrace & PT_PTRACED))
return 0;
if (!(p->ptrace & PT_ATTACHED))
return 1;
/*
* This child was PTRACE_ATTACH'd. We should be seeing it only if
* we are the attacher. If we are the real parent, this is a race
* inside ptrace_attach. It is waiting for the tasklist_lock,
* which we have to switch the parent links, but has already set
* the flags in p->ptrace.
*/
return (p->parent != p->real_parent);
}
static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
int __user *stat_addr, struct rusage __user *ru)
{
DECLARE_WAITQUEUE(wait, current);
struct task_struct *tsk;
int flag, retval;
add_wait_queue(&current->signal->wait_chldexit,&wait);
repeat:
/*
* We will set this flag if we see any child that might later
* match our criteria, even if we are not able to reap it yet.
*/
flag = 0;
current->state = TASK_INTERRUPTIBLE;
read_lock(&tasklist_lock);
tsk = current;
do {
struct task_struct *p;
struct list_head *_p;
int ret;
list_for_each(_p,&tsk->children) {
p = list_entry(_p,struct task_struct,sibling);
ret = eligible_child(pid, options, p);
if (!ret)
continue;
switch (p->state) {
case TASK_TRACED:
if (!my_ptrace_child(p))
continue;
/*FALLTHROUGH*/
case TASK_STOPPED:
/*
* It's stopped now, so it might later
* continue, exit, or stop again.
*/
flag = 1;
if (!(options & WUNTRACED) &&
!my_ptrace_child(p))
continue;
retval = wait_task_stopped(p, ret == 2,
(options & WNOWAIT),
infop,
stat_addr, ru);
if (retval == -EAGAIN)
goto repeat;
if (retval != 0) /* He released the lock. */
goto end;
break;
default:
// case EXIT_DEAD:
if (p->exit_state == EXIT_DEAD)
continue;
// case EXIT_ZOMBIE:
if (p->exit_state == EXIT_ZOMBIE) {
/*
* Eligible but we cannot release
* it yet:
*/
if (ret == 2)
goto check_continued;
if (!likely(options & WEXITED))
continue;
retval = wait_task_zombie(
p, (options & WNOWAIT),
infop, stat_addr, ru);
/* He released the lock. */
if (retval != 0)
goto end;
break;
}
check_continued:
/*
* It's running now, so it might later
* exit, stop, or stop and then continue.
*/
flag = 1;
if (!unlikely(options & WCONTINUED))
continue;
retval = wait_task_continued(
p, (options & WNOWAIT),
infop, stat_addr, ru);
if (retval != 0) /* He released the lock. */
goto end;
break;
}
}
if (!flag) {
list_for_each(_p, &tsk->ptrace_children) {
p = list_entry(_p, struct task_struct,
ptrace_list);
if (!eligible_child(pid, options, p))
continue;
flag = 1;
break;
}
}
if (options & __WNOTHREAD)
break;
tsk = next_thread(tsk);
if (tsk->signal != current->signal)
BUG();
} while (tsk != current);
read_unlock(&tasklist_lock);
if (flag) {
retval = 0;
if (options & WNOHANG)
goto end;
retval = -ERESTARTSYS;
if (signal_pending(current))
goto end;
schedule();
goto repeat;
}
retval = -ECHILD;
end:
current->state = TASK_RUNNING;
remove_wait_queue(&current->signal->wait_chldexit,&wait);
if (infop) {
if (retval > 0)
retval = 0;
else {
/*
* For a WNOHANG return, clear out all the fields
* we would set so the user can easily tell the
* difference.
*/
if (!retval)
retval = put_user(0, &infop->si_signo);
if (!retval)
retval = put_user(0, &infop->si_errno);
if (!retval)
retval = put_user(0, &infop->si_code);
if (!retval)
retval = put_user(0, &infop->si_pid);
if (!retval)
retval = put_user(0, &infop->si_uid);
if (!retval)
retval = put_user(0, &infop->si_status);
}
}
return retval;
}
asmlinkage long sys_waitid(int which, pid_t pid,
struct siginfo __user *infop, int options,
struct rusage __user *ru)
{
long ret;
if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
return -EINVAL;
if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
return -EINVAL;
switch (which) {
case P_ALL:
pid = -1;
break;
case P_PID:
if (pid <= 0)
return -EINVAL;
break;
case P_PGID:
if (pid <= 0)
return -EINVAL;
pid = -pid;
break;
default:
return -EINVAL;
}
ret = do_wait(pid, options, infop, NULL, ru);
/* avoid REGPARM breakage on x86: */
prevent_tail_call(ret);
return ret;
}
asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
int options, struct rusage __user *ru)
{
long ret;
if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
__WNOTHREAD|__WCLONE|__WALL))
return -EINVAL;
ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
/* avoid REGPARM breakage on x86: */
prevent_tail_call(ret);
return ret;
}
#ifdef __ARCH_WANT_SYS_WAITPID
/*
* sys_waitpid() remains for compatibility. waitpid() should be
* implemented by calling sys_wait4() from libc.a.
*/
asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
{
return sys_wait4(pid, stat_addr, options, NULL);
}
#endif
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