linux-kernel - Re: [PATCH linux-next] signal: Remove outdated __send_signal references in do_notify

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Message-ID: <20250728155815.GB25567@redhat.com>
Date: Mon, 28 Jul 2025 17:58:16 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: fan.yu9@....com.cn, frederic@...nel.org, peterz@...radead.org,
	brauner@...nel.org, iro@...iv.linux.org.uk,
	joel.granados@...nel.org, lorenzo.stoakes@...cle.com,
	linux-kernel@...r.kernel.org, xu.xin16@....com.cn,
	yang.yang29@....com.cn
Subject: Re: [PATCH linux-next] signal: Remove outdated __send_signal
 references in  do_notify_parent

On 07/28, Thomas Gleixner wrote:
>
> > --- a/kernel/signal.c
> > +++ b/kernel/signal.c
> > @@ -2251,10 +2251,7 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
> >  		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
> >  			sig = 0;
> >  	}
> > -	/*
> > -	 * Send with __send_signal as si_pid and si_uid are in the
> > -	 * parent's namespaces.
> > -	 */
> > +
>
> Why are you removing the complete comment instead of just renaming the
> stale reference?

Then the comment should be updated to explain that we have to use
__send_signal_locked(), not send_signal_locked(), because the latter
can wrongly change si_pid/si_uid which are in the parent's namespace.

> commit 61e713bdca36 ("signal: Avoid corrupting si_pid and si_uid in
> do_notify_parent") put that comment there for a reason.

Yes, but the comment was a bit confusing, imo. I don't think it makes
the code more clear.

But I am fine either way.

Oleg.