/**
* freeze_task - send a freeze request to given task
* @p: task to send the request to
* @sig_only: if set, the request will only be sent if the task has the
* PF_FREEZER_NOSIG flag unset
* Return value: 'false', if @sig_only is set and the task has
* PF_FREEZER_NOSIG set or the task is frozen, 'true', otherwise
*
* The freeze request is sent by setting the tasks's TIF_FREEZE flag and
* either sending a fake signal to it or waking it up, depending on whether
* or not it has PF_FREEZER_NOSIG set. If @sig_only is set and the task
* has PF_FREEZER_NOSIG set (ie. it is a typical kernel thread), its
* TIF_FREEZE flag will not be set.
*/
bool freeze_task(struct task_struct *p, bool sig_only)
{
/*
* We first check if the task is freezing and next if it has already
* been frozen to avoid the race with frozen_process() which first marks
* the task as frozen and next clears its TIF_FREEZE.
*/
if (!freezing(p)) {
rmb();
if (frozen(p))
return false;
if (!sig_only || should_send_signal(p))
set_freeze_flag(p);
else
return false;
}
if (should_send_signal(p)) {
if (!signal_pending(p))
fake_signal_wake_up(p);
} else if (sig_only) {
return false;
} else {
wake_up_state(p, TASK_INTERRUPTIBLE);
}
return true;
}
static int ptrace_detach(struct task_struct *child, unsigned int data)
{
bool dead = false;
if (!valid_signal(data))
return -EIO;
/* Architecture-specific hardware disable .. */
ptrace_disable(child);
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
write_lock_irq(&tasklist_lock);
/*
* This child can be already killed. Make sure de_thread() or
* our sub-thread doing do_wait() didn't do release_task() yet.
*/
if (child->ptrace) {
child->exit_code = data;
dead = __ptrace_detach(current, child);
if (!child->exit_state)
wake_up_state(child, TASK_TRACED | TASK_STOPPED);
}
write_unlock_irq(&tasklist_lock);
if (unlikely(dead))
release_task(child);
return 0;
}
/**
* freeze_task - send a freeze request to given task
* @p: task to send the request to
* @sig_only: if set, the request will only be sent if the task has the
* PF_FREEZER_NOSIG flag unset
* Return value: 'false', if @sig_only is set and the task has
* PF_FREEZER_NOSIG set or the task is frozen, 'true', otherwise
*
* The freeze request is sent by setting the tasks's TIF_FREEZE flag and
* either sending a fake signal to it or waking it up, depending on whether
* or not it has PF_FREEZER_NOSIG set. If @sig_only is set and the task
* has PF_FREEZER_NOSIG set (ie. it is a typical kernel thread), its
* TIF_FREEZE flag will not be set.
*/
bool freeze_task(struct task_struct *p, bool sig_only)
{
/*
* We first check if the task is freezing and next if it has already
* been frozen to avoid the race with frozen_process() which first marks
* the task as frozen and next clears its TIF_FREEZE.
*/
if (!freezing(p)) {
smp_rmb();
if (frozen(p))
return false;
if (!sig_only || should_send_signal(p))
set_freeze_flag(p);
else
return false;
}
if (should_send_signal(p)) {
fake_signal_wake_up(p);
/*
* fake_signal_wake_up() goes through p's scheduler
* lock and guarantees that TASK_STOPPED/TRACED ->
* TASK_RUNNING transition can't race with task state
* testing in try_to_freeze_tasks().
*/
} else if (sig_only) {
return false;
} else {
wake_up_state(p, TASK_INTERRUPTIBLE);
}
return true;
}
static int ptrace_resume(struct task_struct *child, long request,
unsigned long data)
{
if (!valid_signal(data))
return -EIO;
if (request == PTRACE_SYSCALL)
set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
else
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
#ifdef TIF_SYSCALL_EMU
if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
else
clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
#endif
if (is_singleblock(request)) {
if (unlikely(!arch_has_block_step()))
return -EIO;
user_enable_block_step(child);
} else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
if (unlikely(!arch_has_single_step()))
return -EIO;
user_enable_single_step(child);
} else {
user_disable_single_step(child);
}
child->exit_code = data;
wake_up_state(child, __TASK_TRACED);
return 0;
}
/**
* freeze_task - send a freeze request to given task
* @p: task to send the request to
*
* If @p is freezing, the freeze request is sent either by sending a fake
* signal (if it's not a kernel thread) or waking it up (if it's a kernel
* thread).
*
* RETURNS:
* %false, if @p is not freezing or already frozen; %true, otherwise
*/
bool freeze_task(struct task_struct *p)
{
unsigned long flags;
/*
* This check can race with freezer_do_not_count, but worst case that
* will result in an extra wakeup being sent to the task. It does not
* race with freezer_count(), the barriers in freezer_count() and
* freezer_should_skip() ensure that either freezer_count() sees
* freezing == true in try_to_freeze() and freezes, or
* freezer_should_skip() sees !PF_FREEZE_SKIP and freezes the task
* normally.
*/
if (freezer_should_skip(p))
return false;
spin_lock_irqsave(&freezer_lock, flags);
if (!freezing(p) || frozen(p)) {
spin_unlock_irqrestore(&freezer_lock, flags);
return false;
}
if (!(p->flags & PF_KTHREAD))
fake_signal_wake_up(p);
else
wake_up_state(p, TASK_INTERRUPTIBLE);
spin_unlock_irqrestore(&freezer_lock, flags);
return true;
}
bool freeze_task(struct task_struct *p, bool sig_only)
{
if (!freezing(p)) {
rmb();
if (frozen(p))
return false;
if (!sig_only || should_send_signal(p))
set_freeze_flag(p);
else
return false;
}
if (should_send_signal(p)) {
if (!signal_pending(p))
fake_signal_wake_up(p);
} else if (sig_only) {
return false;
} else {
wake_up_state(p, TASK_INTERRUPTIBLE);
}
return true;
}
/**
* freeze_task - send a freeze request to given task
* @p: task to send the request to
*
* If @p is freezing, the freeze request is sent by setting %TIF_FREEZE
* flag and either sending a fake signal to it or waking it up, depending
* on whether it has %PF_FREEZER_NOSIG set.
*
* RETURNS:
* %false, if @p is not freezing or already frozen; %true, otherwise
*/
bool freeze_task(struct task_struct *p)
{
unsigned long flags;
spin_lock_irqsave(&freezer_lock, flags);
if (!freezing(p) || frozen(p)) {
spin_unlock_irqrestore(&freezer_lock, flags);
return false;
}
if (!(p->flags & PF_KTHREAD)) {
fake_signal_wake_up(p);
/*
* fake_signal_wake_up() goes through p's scheduler
* lock and guarantees that TASK_STOPPED/TRACED ->
* TASK_RUNNING transition can't race with task state
* testing in try_to_freeze_tasks().
*/
} else {
wake_up_state(p, TASK_INTERRUPTIBLE);
}
spin_unlock_irqrestore(&freezer_lock, flags);
return true;
}
static void ptrace_unfreeze_traced(struct task_struct *task)
{
if (task->state != __TASK_TRACED)
return;
WARN_ON(!task->ptrace || task->parent != current);
spin_lock_irq(&task->sighand->siglock);
if (__fatal_signal_pending(task))
wake_up_state(task, __TASK_TRACED);
else
task->state = TASK_TRACED;
spin_unlock_irq(&task->sighand->siglock);
}
static void __kthread_unpark(struct task_struct *k, struct kthread *kthread)
{
clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
/*
* We clear the IS_PARKED bit here as we don't wait
* until the task has left the park code. So if we'd
* park before that happens we'd see the IS_PARKED bit
* which might be about to be cleared.
*/
if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
__kthread_bind(k, kthread->cpu, TASK_PARKED);
wake_up_state(k, TASK_PARKED);
}
}
/**
* freeze_task - send a freeze request to given task
* @p: task to send the request to
* @with_mm_only: if set, the request will only be sent if the task has its
* own mm
* Return value: 0, if @with_mm_only is set and the task has no mm of its
* own or the task is frozen, 1, otherwise
*
* The freeze request is sent by seting the tasks's TIF_FREEZE flag and
* either sending a fake signal to it or waking it up, depending on whether
* or not it has its own mm (ie. it is a user land task). If @with_mm_only
* is set and the task has no mm of its own (ie. it is a kernel thread),
* its TIF_FREEZE flag should not be set.
*
* The task_lock() is necessary to prevent races with exit_mm() or
* use_mm()/unuse_mm() from occuring.
*/
static int freeze_task(struct task_struct *p, int with_mm_only)
{
int ret = 1;
task_lock(p);
if (freezing(p)) {
if (has_mm(p)) {
if (!signal_pending(p))
fake_signal_wake_up(p, 0);
} else {
if (with_mm_only)
ret = 0;
else
wake_up_state(p, TASK_INTERRUPTIBLE);
}
} else {
rmb();
if (frozen(p)) {
ret = 0;
} else {
if (has_mm(p)) {
set_freeze_flag(p);
send_fake_signal(p);
} else {
if (with_mm_only) {
ret = 0;
} else {
set_freeze_flag(p);
wake_up_state(p, TASK_INTERRUPTIBLE);
}
}
}
}
task_unlock(p);
return ret;
}
/**
* freeze_task - send a freeze request to given task
* @p: task to send the request to
*
* If @p is freezing, the freeze request is sent either by sending a fake
* signal (if it's not a kernel thread) or waking it up (if it's a kernel
* thread).
*
* RETURNS:
* %false, if @p is not freezing or already frozen; %true, otherwise
*/
bool freeze_task(struct task_struct *p)
{
unsigned long flags;
spin_lock_irqsave(&freezer_lock, flags);
if (!freezing(p) || frozen(p)) {
spin_unlock_irqrestore(&freezer_lock, flags);
return false;
}
if (!(p->flags & PF_KTHREAD))
fake_signal_wake_up(p);
else
wake_up_state(p, TASK_INTERRUPTIBLE);
spin_unlock_irqrestore(&freezer_lock, flags);
return true;
}
/**
* freeze_task - send a freeze request to given task
* @p: task to send the request to
*
* If @p is freezing, the freeze request is sent either by sending a fake
* signal (if it's not a kernel thread) or waking it up (if it's a kernel
* thread).
*
* RETURNS:
* %false, if @p is not freezing or already frozen; %true, otherwise
*/
bool freeze_task(struct task_struct *p)
{
unsigned long flags;
/*
* This check can race with freezer_do_not_count, but worst case that
* will result in an extra wakeup being sent to the task. It does not
* race with freezer_count(), the barriers in freezer_count() and
* freezer_should_skip() ensure that either freezer_count() sees
* freezing == true in try_to_freeze() and freezes, or
* freezer_should_skip() sees !PF_FREEZE_SKIP and freezes the task
* normally.
*/
if (freezer_should_skip(p))
return false;
spin_lock_irqsave(&freezer_lock, flags);
if (!freezing(p) || frozen(p)) {
spin_unlock_irqrestore(&freezer_lock, flags);
return false;
}
if (!(p->flags & PF_KTHREAD)) {
fake_signal_wake_up(p);
/*
* fake_signal_wake_up() goes through p's scheduler
* lock and guarantees that TASK_STOPPED/TRACED ->
* TASK_RUNNING transition can't race with task state
* testing in try_to_freeze_tasks().
*/
} else {
wake_up_state(p, TASK_INTERRUPTIBLE);
}
spin_unlock_irqrestore(&freezer_lock, flags);
return true;
}