linux-kernel - Re: [PATCH] random: make consistent usage of crng

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Message-ID: <CAHmME9p2v664oLNAv74H=tu3CFVwxtEUw5M9neOAred6pR3FDg@mail.gmail.com>
Date:   Sat, 12 Mar 2022 16:58:06 -0700
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        "Theodore Ts'o" <tytso@....edu>
Subject: Re: [PATCH] random: make consistent usage of crng_ready()

Hi Eric,

On Sat, Mar 12, 2022 at 1:09 PM Eric Biggers <ebiggers@...nel.org> wrote:
>
> On Tue, Mar 08, 2022 at 11:25:17AM -0700, Jason A. Donenfeld wrote:
> > diff --git a/drivers/char/random.c b/drivers/char/random.c
> > index 69591d599338..e37ae7ef039c 100644
> > --- a/drivers/char/random.c
> > +++ b/drivers/char/random.c
> > @@ -123,7 +123,7 @@ static void try_to_generate_entropy(void);
> >   */
> >  int wait_for_random_bytes(void)
> >  {
> > -     if (likely(crng_ready()))
> > +     if (crng_ready())
> >               return 0;
> >
> >       do {
> ...
> >       } while (!crng_ready());
>
> I guess the reason why the above doesn't simply use a 'while' loop is because
> someone wanted 'likely()' on the first crng_ready()?  That doesn't actually
> apply, since crng_ready() has likely() itself, it should just be a 'while' loop.

Nice catch, thanks.

Jason