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From:   Jeff Moyer <jmoyer@redhat.com>
To:     Matteo Rizzo <matteorizzo@google.com>
Cc:     Ricardo Ribalda <ribalda@chromium.org>,
        Bart Van Assche <bvanassche@acm.org>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
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        dave.hansen@linux.intel.com, chenhuacai@kernel.org, steve@sk2.org,
        gpiccoli@igalia.com, ldufour@linux.ibm.com
Subject: Re: [PATCH 1/1] Add a new sysctl to disable io_uring system-wide
References: <20230627120058.2214509-1-matteorizzo@google.com>
        <20230627120058.2214509-2-matteorizzo@google.com>
        <e8924389-985a-42ad-9daf-eca2bf12fa57@acm.org>
        <CAHKB1wJANtT27WM6hrhDy_x9H9Lsn4qRjPDmXdKosoL93TJRYg@mail.gmail.com>
        <CANiDSCvjCoj3Q3phbmdhdG-veHNRrfD-gBu=FuZkmrgJ2uxiJg@mail.gmail.com>
        <CAHKB1w+UyOnC_rOBABVhmzG+XeePaWYgPJWxX9NUeqnAi9WcgA@mail.gmail.com>
Date:   Wed, 28 Jun 2023 11:59:56 -0400
In-Reply-To: <CAHKB1w+UyOnC_rOBABVhmzG+XeePaWYgPJWxX9NUeqnAi9WcgA@mail.gmail.com>
        (Matteo Rizzo's message of "Wed, 28 Jun 2023 17:12:42 +0200")
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Matteo Rizzo <matteorizzo@google.com> writes:

> On Wed, 28 Jun 2023 at 13:44, Ricardo Ribalda <ribalda@chromium.org> wrote:
>>
>> Have you considered that the new sysctl is "sticky like kexec_load_disabled.
>> When the user disables it there is no way to turn it back on until the
>> system is rebooted.
>
> Are you suggesting making this sysctl sticky? Are there any examples of how to
> implement a sticky sysctl that can take more than 2 values in case we want to
> add an intermediate level that still allows privileged processes to use
> io_uring? Also, what would be the use case? Preventing privileged processes
> from re-enabling io_uring?

See unprivileged_bpf_disabled for an example.  I can't speak to the use
case for a sticky value.

-Jeff