linux-kernel - Re: [PATCH] random: do not export add_vmfork

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Message-ID: <Yh5tPt2LoLp442zi@mit.edu>
Date:   Tue, 1 Mar 2022 14:00:14 -0500
From:   "Theodore Ts'o" <tytso@....edu>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-kernel@...r.kernel.org,
        Dominik Brodowski <linux@...inikbrodowski.net>
Subject: Re: [PATCH] random: do not export add_vmfork_randomness() unless
 needed

On Tue, Mar 01, 2022 at 03:25:28PM +0100, Jason A. Donenfeld wrote:
> Since add_vmfork_randomness() is only called from vmgenid.o, we can
> guard it in CONFIG_VMGENID, similarly to how we do with
> add_disk_randomness() and CONFIG_BLOCK. If we ever have multiple things
> calling into add_vmfork_randomness(), we can add another shared Kconfig
> symbol for that, but for now, this is good enough. Even though
> add_vmfork_randomess() is a pretty small function, removing it means
> that there are only calls to crng_reseed(false) and none to
> crng_reseed(true), which means the compiler can constant propagate it
> and simply crng_reseed().

How about only exporting add_vmfork_randomness if VMGENID is compiled
as a module?  If it's built-in to the kernel, no need to export the
symbol.

					- Ted