Re: [PATCH] pipe_read: don't wake up the writer if the pipe is still full

[Hillf Danton]

On Wed, 5 Mar 2025 00:49:09 +0100 Oleg Nesterov <oleg@xxxxxxxxxx>
> 
> Of course! Again, whatever the woken writer checks in pipe_writable()
> lockless, another writer can make pipe_full() true again.
> 
> But why do we care? Why do you think that the change you propose makes

Because of the hang reported.

> more sense than the fix from Prateek or the (already merged) Linus's fix?
> 
See the loop in  ___wait_event(),

	for (;;) {
		prepare_to_wait_event();

		// flip
		if (condition)
			break;

		schedule();
	}

After wakeup, waiter will sleep again if condition flips false on the waker
side before waiter checks condition, even if condition is atomic, no?