Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 14 Aug 2023 08:49:07 -0700
From:   Stephen Hemminger <stephen@networkplumber.org>
To:     Francois Michel <francois.michel@uclouvain.be>
Cc:     Jamal Hadi Salim <jhs@mojatatu.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Jiri Pirko <jiri@resnulli.us>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 2/3] [PATCH 2/3] netem: allow using a seeded
 PRNG for generating random losses
Message-ID: <20230814084907.18c339c2@hermes.local>
In-Reply-To: <20230814023147.1389074-3-francois.michel@uclouvain.be>
References: <20230814023147.1389074-1-francois.michel@uclouvain.be>
        <20230814023147.1389074-3-francois.michel@uclouvain.be>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Mon, 14 Aug 2023 04:31:39 +0200
Francois Michel <francois.michel@uclouvain.be> wrote:

> +/* netem_get_random_u32 - polls a new random 32-bits integer from
> + * the prng.
> + * Uses a deterministic seeded prng if p->deterministic_rng is true.
> + * Uses get_random_u32() underneath if p is NULL or if p->deterministic_=
rng
> + * is false.
> + */
> +static u32 netem_get_random_u32(struct prng *p)

Overall I am fine with this patch, but the function name is getting excessi=
vely
long. It is a local function, so no need for netem_ prefix.

Checking for p =3D=3D NULL is redundant, all callers are passing a valid po=
inter.

For logical consistency, put the new wrapper before init_crandom() and afte=
r netem_skb_cb().

Since this is not security related, the change could also be simplified to =
just
always prandom_u32_state() and initialize the state on first use with eithe=
r=20
get_random or provided seed.  This would also simplify the code around stor=
ing
original seed and boolean.

Reminds me of the quote attributed to Mark Twain:
=E2=80=9CI apologize for such a long letter - I didn't have time to write a=
 short one.=E2=80=9D