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From:   Florian Weimer <fweimer@redhat.com>
To:     ebiederm@xmission.com (Eric W. Biederman)
Cc:     =?utf-8?Q?J=C3=BCrg?= Billeter <j@bitron.ch>,
        Christian Brauner <christian@brauner.io>,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
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        akpm@linux-foundation.org, oleg@redhat.com, cyphar@cyphar.com,
        viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org,
        dancol@google.com, timmurray@google.com, linux-man@vger.kernel.org,
        keescook@chromium.org, tglx@linutronix.de, x86@kernel.org
Subject: Re: [PATCH v4] signal: add taskfd_send_signal() syscall
References: <20181206121858.12215-1-christian@brauner.io>
        <87h8fq7s84.fsf@oldenburg2.str.redhat.com>
        <b0e946bcac12358841c9a99017da819b00794d9c.camel@bitron.ch>
        <87pnue6bp2.fsf@oldenburg2.str.redhat.com>
        <87efaun587.fsf@xmission.com>
Date:   Thu, 06 Dec 2018 14:44:36 +0100
In-Reply-To: <87efaun587.fsf@xmission.com> (Eric W. Biederman's message of
        "Thu, 06 Dec 2018 07:40:24 -0600")
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* Eric W. Biederman:

> Floriam are you seeing a problem with this behavior or the way Christian
> was describing it?

My hope is that you could use taskfd_send_signal one day to send a
signal to a process which you *known* (based on how you've written your
application) should be running and not in a zombie state, and get back
an error if it has exited.

If you get this error, only then you wait on the process, using the file
descriptor you have, and run some recovery code.

Wouldn't that be a reasonable approach once we've got task descriptors?

Thanks,
Florian