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Date:   Wed, 25 Oct 2023 22:13:00 +0200 (CEST)
From:   Richard Weinberger <richard@nod.at>
To:     Petr Vorel <pvorel@suse.cz>
Cc:     linux-nfs <linux-nfs@vger.kernel.org>,
        Steve Dickson <steved@redhat.com>
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In-Reply-To: <20231025194701.456031-1-pvorel@suse.cz>
References: <20231025194701.456031-1-pvorel@suse.cz>
Subject: Re: [PATCH 0/3] Add getrandom() fallback, cleanup headers
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----- Ursprüngliche Mail -----
> Von: "Petr Vorel" <pvorel@suse.cz>
> I also wonder why getrandom() syscall does not called with GRND_NONBLOCK
> flag. Is it ok/needed to block?

With GRND_NONBLOCK it would return EAGAIN if not enough
randomness is ready. How to handle this then? Aborting the start of the daemon?

Before we other think the whole thing, the sole purpose of the getrandom()
call is seeding libc's PRNG with srand() to give every waiter a different
amount of sleep time upon concurrent database access.
See wait_for_dbaccess() and handling of SQLITE_LOCKED.

I'm pretty sure instead of seeding from getrandom() we can also use the current
time or read a few bytes from /dev/urandom.
Just make sure that every user of sqlite_plug_init() has a different seed.

Thanks,
//richard