linux-kernel - Re: [PATCH] signal: don't silently convert SI

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Date:   Wed, 17 Apr 2019 15:16:03 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Christian Brauner <christian@...uner.io>
Cc:     Jann Horn <jannh@...gle.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Arnd Bergmann <arnd@...db.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] signal: don't silently convert SI_USER signals to
 non-current pidfd

On 04/17, Christian Brauner wrote:
>
> On Mon, Apr 08, 2019 at 03:13:16PM +0200, Oleg Nesterov wrote:
> >
> > but perhaps it should always fail, even if task_pid(current) == pid.
> >
> > sys_rt_sigqueueinfo() allows to send any siginfo to yourself, but this is only needed
> > for checkpoint/restart.
>
> Yes, that's why this was added. I would leave it in exactly because of
> checkpoint/restart.

I don't understand...

c/r doesn't need this "feature" in pidfd_send_signal(), so it can be removed.
But,

> I have sympathies for "this [...] project by various
> mad Russians" [1] and it doesn't really hurt us. :)

I won't argue, I agree it doesn't hurt and looks consistent with sys_rt_sigqueueinfo.

Oleg.