linux-kernel - Re: [PATCH v3] random: handle archrandom with multiple longs

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Message-ID: <CAHmME9p_9j_B2d1h3cKVbv=ucNAa9_grBBW_jdWa8GTbm5WpZg@mail.gmail.com>
Date:   Mon, 25 Jul 2022 11:37:23 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     David Laight <David.Laight@...lab.com>
Cc:     Borislav Petkov <bp@...e.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>, Will Deacon <will@...nel.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Johannes Berg <johannes@...solutions.net>,
        Mark Rutland <mark.rutland@....com>,
        Harald Freudenberger <freude@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH v3] random: handle archrandom with multiple longs

On Mon, Jul 25, 2022 at 11:36 AM David Laight <David.Laight@...lab.com> wrote:
>
> ...
> > More directly, the reason we don't want to error is because the use case
> > has fallbacks meant to handle errors. The cascade looks like this
> > (quoting from the other email):
> >
> >     unsigned long array[whatever];
> >     for (i = 0; i < ARRAY_SIZE(array);) {
> >         longs = arch_get_random_seed_longs(&array[i], ARRAY_SIZE(array) - i);
> >         if (longs) {
> >             i += longs;
> >             continue;
> >         }
> >         longs = arch_get_random_longs(&array[i], ARRAY_SIZE(array) - i);
> >         if (longs) {
> >             i += longs;
> >             continue;
> >         }
> >         array[i++] = random_get_entropy();
> >     }
> >
> > It tries to get the best that it can as much as it can, but isn't going
> > to block or do anything too nuts for that.
>
> Do you really want to retry the earlier calls that returned no data?

Does the above code do that?