Re: [PATCH/RFC] core/nfsd: allow kernel threads to use task_work.

[Oleg Nesterov <oleg@xxxxxxxxxx>]

On 11/28, Christian Brauner wrote:
>
> Should be simpler if you invert the logic?
>
> COMPLETELY UNTESTED

Agreed, this looks much better to me. But perhaps we can just add the new
PF_KTHREAD_XXX flag and change fput


	--- a/fs/file_table.c
	+++ b/fs/file_table.c
	@@ -445,7 +445,8 @@ void fput(struct file *file)
		if (atomic_long_dec_and_test(&file->f_count)) {
			struct task_struct *task = current;
	 
	-		if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
	+		if (likely(!in_interrupt() &&
	+		    task->flags & (PF_KTHREAD|PF_KTHREAD_XXX) != PF_KTHREAD) {
				init_task_work(&file->f_rcuhead, ____fput);
				if (!task_work_add(task, &file->f_rcuhead, TWA_RESUME))
					return;

?

Then nfsd() can simply set PF_KTHREAD_XXX. This looks even simpler to me.

Oleg.