On Thu, Feb 20, 2020 at 01:31:48PM -0700, Jens Axboe wrote:
> This is similar to the task_works, and uses the same infrastructure, but
> the sched_work list is run when the task is being scheduled in or out.
>
> The intended use case here is for core code to be able to add work
> that should be automatically run by the task, without the task needing
> to do anything. This is done outside of the task, one example would be
> from waitqueue handlers, or anything else that is invoked out-of-band
> from the task itself.
>
> diff --git a/kernel/task_work.c b/kernel/task_work.c
> index 3445421266e7..ba62485d5b3d 100644
> --- a/kernel/task_work.c
> +++ b/kernel/task_work.c
> @@ -3,7 +3,14 @@
> #include <linux/task_work.h>
> #include <linux/tracehook.h>
>
> -static struct callback_head work_exited; /* all we need is ->next == NULL */
> +static void task_exit_func(struct callback_head *head)
> +{
> +}
> +
> +static struct callback_head work_exited = {
> + .next = NULL,
> + .func = task_exit_func,
> +};
Do we really need this? It seems to suggest we're trying to execute
work_exited, which would be an error.
Doing so would be the result of calling sched_work_run() after
exit_task_work(). I suppose that's actually possible.. the problem is
that that would reset sched_work to NULL and re-allow queueing works,
which would then leak.
I'll look at it in more detail tomorrow, I'm tired...
