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Date: Fri, 2 Feb 2024 13:50:25 +0100
From: Christian Brauner <brauner@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>, 
	Tycho Andersen <tycho@tycho.pizza>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/1] pidfd: implement PIDFD_THREAD flag for
 pidfd_open()
Message-ID: <20240202-helium-eurem-f63c0f9328c0@brauner>
References: <20240131132541.GA23632@redhat.com>
 <20240131132602.GA23641@redhat.com>
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In-Reply-To: <20240131132602.GA23641@redhat.com>

> @@ -2050,6 +2051,8 @@ static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
>  
>  	seq_put_decimal_ll(m, "Pid:\t", nr);
>  
> +	/* TODO: report PIDFD_THREAD */

So I think we don't need to do anything here. Since PIDFD_THREAD sets
O_EXCL in file->f_flags and in contrast to do_dentry_open() it isn't
dropped. So userspace can already detect PIDFD_NONBLOCK as O_NONBLOCK
and PIDFD_THREAD as O_EXCL.