linux-kernel - Re: [PATCH 4/7] random: remove unused reserved argument

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Date:   Sun, 16 Jan 2022 14:24:55 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-kernel@...r.kernel.org, tytso@....edu
Subject: Re: [PATCH 4/7] random: remove unused reserved argument

Am Thu, Jan 13, 2022 at 04:44:10PM +0100 schrieb Jason A. Donenfeld:
> This argument is always set to zero, as a result of us not caring about
> keeping a certain amount reserved in the pool these days. So just remove
> it and cleanup the function signatures.
> 
> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>

I'd suggest noting in the patch title and commit message that this relates
to the extract_entropy() function. 

> @@ -1342,7 +1341,7 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
>  	/* never pull more than available */
>  	have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
>  
> -	if ((have_bytes -= reserved) < 0)
> +	if (have_bytes < 0)
>  		have_bytes = 0;
>  	ibytes = min_t(size_t, ibytes, have_bytes);

Hmm. We already WARN_ON(entropy_count < 0) a few lines below. Maybe move
that assertion before the assignement of have_bytes? Then, have_bytes can
never be lower than zero, and the code becomes even simpler. What do you
think?

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

Thanks,
	Dominik