On 03/25, Peter Zijlstra wrote:
>
> static void ptrace_unfreeze_traced(struct task_struct *task)
> {
> - if (task->state != __TASK_TRACED)
> + if (READ_ONCE(task->__state) != __TASK_TRACED)
> return;
this change is correct,
> @@ -201,11 +201,11 @@ static void ptrace_unfreeze_traced(struct task_struct
> *task)
> * Recheck state under the lock to close this race.
> */
> spin_lock_irq(&task->sighand->siglock);
> - if (task->state == __TASK_TRACED) {
> + if (READ_ONCE(task->__state) == __TASK_TRACED) {
this too,
> @@ -240,7 +240,7 @@ static int ptrace_check_attach(struct task_struct *child,
> bool ignore_state)
> */
> read_lock(&tasklist_lock);
> if (child->ptrace && child->parent == current) {
> - WARN_ON(child->state == __TASK_TRACED);
> + WARN_ON(task_is_traced(child));
> /*
> * child->sighand can't be NULL, release_task()
> * does ptrace_unlink() before __exit_signal().
> @@ -257,7 +257,7 @@ static int ptrace_check_attach(struct task_struct *child,
> bool ignore_state)
> * ptrace_stop() changes ->state back to TASK_RUNNING,
> * so we should not worry about leaking __TASK_TRACED.
> */
> - WARN_ON(child->state == __TASK_TRACED);
> + WARN_ON(task_is_traced(child));
the two above are not.
"state == __TASK_TRACED" and task_is_traced() is not the same thing.
"state == __TASK_TRACED" means that debugger changed the state from TASK_TRACED
to __TASK_TRACED (iow, removed TASK_WAKEKILL) to ensure the tracee can not run,
this doesn't affect task_is_traced().
Oleg.
