Re: [PATCH v3 1/3] QIOChannelSocket: Fix zero-copy flush returning code 1 when nothing sent

[Leonardo Bras Soares Passos]

On Thu, Jul 7, 2022 at 7:18 PM Peter Xu <peterx@redhat.com> wrote:
>
> On Thu, Jul 07, 2022 at 06:14:17PM -0300, Leonardo Brás wrote:
> > Having 'if(queued == sent)' will cause us to falsely return '1' in two buggy
> > cases, while 'if queued == 0) will either skip early or go into 'infinite' 
> > loop.
>
> I'm not sure I strictly follow here..
>

Sorry, I was thinking of a different scenario.

> Imagine the case we do flush() twice without sending anything, then in the
> 1st flush we'll see queued>sent, we'll finish flush() until queued==sent.
> Then in the 2nd (continuous) flush() we'll see queued==sent immediately.
>
> IIUC with the current patch we'll return 1 which I think is wrong because
> fallback didn't happen, and if with the change to "if (queued==sent) return
> 0" it'll fix it?

Yes, you are correct.
It's a possible scenario to have a flush happen just after another
without any sending in between.

I will fix it as suggested.

Best regards,
Leo

>
> --
> Peter Xu
>