linux-kernel - Re: [PATCH] pidfd: getfd should always report ESRCH if a task is exiting

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Date: Wed, 7 Feb 2024 10:11:54 +0100
From: Christian Brauner <brauner@...nel.org>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Tycho Andersen <tycho@...ho.pizza>, 
	"Eric W . Biederman" <ebiederm@...ssion.com>, linux-kernel@...r.kernel.org, linux-api@...r.kernel.org, 
	Tycho Andersen <tandersen@...flix.com>
Subject: Re: [PATCH] pidfd: getfd should always report ESRCH if a task is
 exiting

On Tue, Feb 06, 2024 at 08:25:54PM +0100, Oleg Nesterov wrote:
> On 02/06, Tycho Andersen wrote:
> 
> > On Tue, Feb 06, 2024 at 07:06:07PM +0100, Oleg Nesterov wrote:
> > > Or we can check task->files != NULL rather than PF_EXITING.
> > >
> > > To me this looks even better, but looks more confusing without a comment.
> > > OTOH, imo this needs a comment anyway ;)
> >
> > I thought about this, but I didn't really understand the null check in
> > exit_files();
> 
> I guess task->files can be NULL at least if it was cloned with
> kernel_clone_args->no_files == T

Won't this give false positives for vhost workers which do set
->no_files but are user workers? IOW, return -ESRCH even though -EBADF
would be correct in this scenario?