linux-kernel - Re: [PATCH v28 11/12] LRNG - add interface for gathering of raw entropy

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Date:   Wed, 15 Jan 2020 22:48:20 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Stephan Mueller <smueller@...onox.de>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-crypto@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        linux-api@...r.kernel.org,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Alexander E. Patrakov" <patrakov@...il.com>,
        "Ahmed S. Darwish" <darwish.07@...il.com>,
        "Theodore Y. Ts'o" <tytso@....edu>, Willy Tarreau <w@....eu>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Vito Caputo <vcaputo@...garu.com>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.cz>, Ray Strode <rstrode@...hat.com>,
        William Jon McCann <mccann@....edu>,
        zhangjs <zachary@...shancloud.com>,
        Andy Lutomirski <luto@...nel.org>,
        Florian Weimer <fweimer@...hat.com>,
        Lennart Poettering <mzxreary@...inter.de>,
        Nicolai Stange <nstange@...e.de>,
        "Peter, Matthias" <matthias.peter@....bund.de>,
        Marcelo Henrique Cerri <marcelo.cerri@...onical.com>,
        Roman Drahtmueller <draht@...altsekun.de>,
        Neil Horman <nhorman@...hat.com>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH v28 11/12] LRNG - add interface for gathering of raw
 entropy

On 1/15/20 10:43 PM, Stephan Mueller wrote:
> Am Donnerstag, 16. Januar 2020, 01:18:18 CET schrieb Randy Dunlap:
> 
> Hi Randy,
> 
>> On 1/15/20 2:35 AM, Stephan Müller wrote:
>>> CC: "Eric W. Biederman" <ebiederm@...ssion.com>
>>> CC: "Alexander E. Patrakov" <patrakov@...il.com>
>>> CC: "Ahmed S. Darwish" <darwish.07@...il.com>
>>> CC: "Theodore Y. Ts'o" <tytso@....edu>
>>> CC: Willy Tarreau <w@....eu>
>>> CC: Matthew Garrett <mjg59@...f.ucam.org>
>>> CC: Vito Caputo <vcaputo@...garu.com>
>>> CC: Andreas Dilger <adilger.kernel@...ger.ca>
>>> CC: Jan Kara <jack@...e.cz>
>>> CC: Ray Strode <rstrode@...hat.com>
>>> CC: William Jon McCann <mccann@....edu>
>>> CC: zhangjs <zachary@...shancloud.com>
>>> CC: Andy Lutomirski <luto@...nel.org>
>>> CC: Florian Weimer <fweimer@...hat.com>
>>> CC: Lennart Poettering <mzxreary@...inter.de>
>>> CC: Nicolai Stange <nstange@...e.de>
>>> Reviewed-by: Roman Drahtmueller <draht@...altsekun.de>
>>> Tested-by: Roman Drahtmüller <draht@...altsekun.de>
>>> Tested-by: Marcelo Henrique Cerri <marcelo.cerri@...onical.com>
>>> Tested-by: Neil Horman <nhorman@...hat.com>
>>> Signed-off-by: Stephan Mueller <smueller@...onox.de>
>>> ---
>>>
>>>  drivers/char/lrng/Kconfig        |  16 ++
>>>  drivers/char/lrng/Makefile       |   1 +
>>>  drivers/char/lrng/lrng_testing.c | 271 +++++++++++++++++++++++++++++++
>>>  3 files changed, 288 insertions(+)
>>>  create mode 100644 drivers/char/lrng/lrng_testing.c
>>>
>>> diff --git a/drivers/char/lrng/lrng_testing.c
>>> b/drivers/char/lrng/lrng_testing.c new file mode 100644
>>> index 000000000000..0e287eccd622
>>> --- /dev/null
>>> +++ b/drivers/char/lrng/lrng_testing.c
>>> @@ -0,0 +1,271 @@
>>> +// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
>>> +/*
>>> + * Linux Random Number Generator (LRNG) Raw entropy collection tool
>>> + *
>>> + * Copyright (C) 2019 - 2020, Stephan Mueller <smueller@...onox.de>
>>> + */
>>> +
>>> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>> +
>>> +#include <linux/atomic.h>
>>> +#include <linux/bug.h>
>>> +#include <linux/debugfs.h>
>>> +#include <linux/module.h>
>>> +#include <linux/sched.h>
>>> +#include <linux/sched/signal.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/string.h>
>>> +#include <linux/types.h>
>>> +#include <linux/uaccess.h>
>>> +#include <linux/workqueue.h>
>>> +#include <asm/errno.h>
>>> +
>>> +#include "lrng_internal.h"
>>> +
>>> +#define LRNG_TESTING_RINGBUFFER_SIZE	1024
>>> +#define LRNG_TESTING_RINGBUFFER_MASK	(LRNG_TESTING_RINGBUFFER_SIZE - 1)
>>> +
>>> +static u32 lrng_testing_rb[LRNG_TESTING_RINGBUFFER_SIZE];
>>> +static u32 lrng_rb_reader = 0;
>>> +static u32 lrng_rb_writer = 0;
>>> +static atomic_t lrng_testing_enabled = ATOMIC_INIT(0);
>>> +
>>> +static DECLARE_WAIT_QUEUE_HEAD(lrng_raw_read_wait);
>>> +static DEFINE_SPINLOCK(lrng_raw_lock);
>>> +
>>> +/*
>>> + * 0 ==> No boot test, gathering of runtime data allowed
>>> + * 1 ==> Boot test enabled and ready for collecting data, gathering
>>> runtime + *	 data is disabled
>>> + * 2 ==> Boot test completed and disabled, gathering of runtime data is
>>> + *	 disabled
>>> + */
>>> +static u32 boot_test = 0;
>>> +module_param(boot_test, uint, 0644);
>>> +MODULE_PARM_DESC(boot_test, "Enable gathering boot time entropy of the
>>> first" +			    " entropy events");
>>
>> One line for the string, please.
> 
> may I ask the question whether this should be done for all lines with printk 
> statements? As checkpatch.pl will complain if you have lines larger than 80 
> chars and complains about line-broken printk statements, I am always unsure 
> which way to go.
> 
> All printk statements in the patch series have line-broken printk statements.

It's for grep-ability of the strings.
grepping for partial strings would work as is, but then one would need to know
what partial string to search for.

-- 
~Randy