linux-kernel - Re: [PATCH] pidfd: change do_notify_pidfd() to use __wake_up(poll_to

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Message-ID: <ZcJmbUzox6Rd3587@tycho.pizza>
Date: Tue, 6 Feb 2024 10:03:41 -0700
From: Tycho Andersen <tycho@...ho.pizza>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Christian Brauner <brauner@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pidfd: change do_notify_pidfd() to use
 __wake_up(poll_to_key(EPOLLIN))

On Mon, Feb 05, 2024 at 03:13:48PM +0100, Oleg Nesterov wrote:
> rather than wake_up_all(). This way do_notify_pidfd() won't wakeup the
> POLLHUP-only waiters which wait for pid_task() == NULL.
> 
> TODO:
>     - as Christian pointed out, this asks for the new wake_up_all_poll()
>       helper, it can already have other users.
> 
>     - we can probably discriminate the PIDFD_THREAD and non-PIDFD_THREAD
>       waiters, but this needs more work. See
>       https://lore.kernel.org/all/20240205140848.GA15853@redhat.com/
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Reviewed-by: Tycho Andersen <tandersen@...flix.com>