> + if (txwin->user_win) {
> + /*
> + * Window opened by child thread may not be closed when
> + * it exits. So take reference to its pid and release it
> + * when the window is free by parent thread.
> + * Acquire a reference to the task's pid to make sure
> + * pid will not be re-used.
> + */
> + txwin->pid = get_task_pid(current, PIDTYPE_PID);
> + /*
> + * Acquire a reference to the task's mm.
> + */
> + txwin->mm = get_task_mm(current);
> +
> + if (txwin->mm) {
> + mmput(txwin->mm);
> + mmgrab(txwin->mm);
Doesn't the mmgrab need to come before the mmput?
> + mm_context_add_copro(txwin->mm);
> + } else {
> + put_pid(txwin->pid);
> + pr_err("VAS: pid(%d): mm_struct is not found\n",
> + current->pid);
> + rc = -EPERM;
> + goto free_window;
> + }
Also the code is much easier to follow if you handle the error
first and avoid the else:
txwin->mm = get_task_mm(current);
if (!txwin->mm) {
put_pid(txwin->pid);
pr_err("VAS: pid(%d): mm_struct is not found\n",
current->pid);
rc = -EPERM;
goto free_window;
}
mmgrab(txwin->mm);
mmput(txwin->mm);
Also don't you need to take a reference to the struct pid for the
tgid as well?
