linux-kernel - Re: [PATCH] eventpoll: fix missing wakeup for ovflist in ep_poll

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Message-ID: <CACGdZYK7MHJT5qgGWA+3HNquLx=on2hdSVbsj9knvdpx29+C7g@mail.gmail.com>
Date:   Fri, 24 Apr 2020 11:50:01 -0700
From:   Khazhismel Kumykov <khazhy@...gle.com>
To:     Roman Penyaev <rpenyaev@...e.de>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>, r@....cc,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] eventpoll: fix missing wakeup for ovflist in ep_poll_callback

On Fri, Apr 24, 2020 at 3:11 AM Roman Penyaev <rpenyaev@...e.de> wrote:
>
> Hi Khazhismel,
>
> That seems to be correct. The patch you refer 339ddb53d373
> relies on callback path, which *should* wake up, not the path
> which harvests events (thus unnecessary wakeups).  When we add
> a new event to the ->ovflist nobody wakes up the waiters,
> thus missing wakeup. You are right.
>
> May I suggest a small change in order to avoid one new goto?
> We can add a new event in either ->ovflist or ->rdllist and
> then wakeup should happen. So simple 'else if' branch should
> do things right, something like the following:
>

Thanks for the review! I agree, I'll send a v2 without new goto

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