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SubjectRe: [PATCH 2/2] random: move initialization out of reseeding hot path
Am Mon, May 09, 2022 at 02:14:09PM +0200 schrieb Jason A. Donenfeld:
> Initialization happens once -- by way of credit_init_bits() -- and then
> it never happens again. Therefore, it doesn't need to be in
> crng_reseed(), which is a hot path that is called multiple times. It
> also doesn't make sense to have there, as initialization activity is
> better associated with initialization routines.
>
> After the prior commit, crng_reseed() now won't be called by multiple
> concurrent callers, which means that we can safely move the
> "finialize_init" logic into crng_init_bits() unconditionally.
>
> Cc: Dominik Brodowski <linux@dominikbrodowski.net>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
> drivers/char/random.c | 43 +++++++++++++++++++------------------------
> 1 file changed, 19 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index 79409cf27a25..1598bb40376e 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -266,7 +266,6 @@ static void crng_reseed(void)
> unsigned long flags;
> unsigned long next_gen;
> u8 key[CHACHA_KEY_SIZE];
> - bool finalize_init = false;
>
> extract_entropy(key, sizeof(key));
>
> @@ -283,28 +282,9 @@ static void crng_reseed(void)
> ++next_gen;
> WRITE_ONCE(base_crng.generation, next_gen);
> WRITE_ONCE(base_crng.birth, jiffies);
> - if (!crng_ready()) {
> - crng_init = CRNG_READY;
> - finalize_init = true;
> - }
> + crng_init = CRNG_READY;

Why unconditionally (you revert that bit in the static branch patch and make
it conditional again; so I see no reason for that here)?

Otherwise, looks good:

Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>

Thanks,
Dominik

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