linux-ext4 - Re: Linux 5.3-rc8

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Date:   Sun, 15 Sep 2019 09:29:55 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Lennart Poettering <mzxreary@...inter.de>
Cc:     "Ahmed S. Darwish" <darwish.07@...il.com>,
        "Theodore Y. Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.cz>, Ray Strode <rstrode@...hat.com>,
        William Jon McCann <mccann@....edu>,
        "Alexander E. Patrakov" <patrakov@...il.com>,
        zhangjs <zachary@...shancloud.com>, linux-ext4@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: Linux 5.3-rc8

On Sat, Sep 14, 2019 at 11:51 PM Lennart Poettering
<mzxreary@...inter.de> wrote:
>
> Oh man. Just spend 5min to understand the situation, before claiming
> this was garbage or that was garbage. The code above does not block
> boot.

Yes it does. You clearly didn't read the thread.

> It blocks startup of services that explicit order themselves
> after the code above. There's only a few services that should do that,
> and the main system boots up just fine without waiting for this.

That's a nice theory, but it doesn't actually match reality.

There are clearly broken setups that use this for things that it
really shouldn't be used for. Asking for true randomness at boot
before there is any indication that randomness exists, and then just
blocking with no further action that could actually _generate_ said
randomness.

If your description was true that the system would come up and be
usable while the blocked thread is waiting for that to happen, things
would be fine.

But that simply isn't the case.

                  Linus