linux-kernel - Re: [PATCH 1/3] seccomp: interrupt SECCOMP_IOCTL_NOTIF

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Message-ID: <20240523085859.GB15163@redhat.com>
Date: Thu, 23 May 2024 10:59:00 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Andrei Vagin <avagin@...gle.com>
Cc: Kees Cook <keescook@...omium.org>,
	Andy Lutomirski <luto@...capital.net>,
	Will Drewry <wad@...omium.org>,
	Christian Brauner <brauner@...nel.org>,
	linux-kernel@...r.kernel.org,
	Tycho Andersen <tandersen@...flix.com>,
	Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH 1/3] seccomp: interrupt SECCOMP_IOCTL_NOTIF_RECV when all
 users have exited

Hi Andrei,

the patch looks good to me even if I don't really understand what
SECCOMP_IOCTL_NOTIF_RECV does. But let me ask a stupid question,

On 05/23, Andrei Vagin wrote:
>
> The change is based on the 'commit 99cdb8b9a573 ("seccomp: notify about
> unused filter")' which implemented (E)POLLHUP notifications.

To me this patch fixes the commit above, because without this change

> @@ -1466,7 +1466,7 @@ static int recv_wake_function(wait_queue_entry_t *wait, unsigned int mode, int s
>  				  void *key)
>  {
>  	/* Avoid a wakeup if event not interesting for us. */
> -	if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR)))
> +	if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR | EPOLLHUP)))

__seccomp_filter_orphan() -> wake_up_poll(&orig->wqh, EPOLLHUP) won't
wakeup the task sleeping in recv_wait_event(), right ?

In any case, FWIW

Reviewed-by: Oleg Nesterov <oleg@...hat.com>