LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Thierry Escande <thierry.escande@linaro.org>
To: Steven Rostedt <rostedt@goodmis.org>, Petr Mladek <pmladek@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	David Miller <davem@davemloft.net>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	"Tobin C . Harding" <me@tobin.cc>,
	linux-kernel@vger.kernel.org,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH RESEND] lib/test_printf.c: call wait_for_random_bytes() before plain %p tests
Date: Fri, 22 Jun 2018 23:50:20 +0200	[thread overview]
Message-ID: <a2f0729c-593e-b747-a22f-6468ea88882e@linaro.org> (raw)
In-Reply-To: <20180622205346.owyjk33wplzh7nhs@home.goodmis.org>

On 22/06/2018 22:53, Steven Rostedt wrote:
> On Thu, Jun 07, 2018 at 02:24:34PM +0200, Petr Mladek wrote:
>> On Mon 2018-06-04 13:37:08, Thierry Escande wrote:
>>> If the test_printf module is loaded before the crng is initialized, the
>>> plain 'p' tests will fail because the printed address will not be hashed
>>> and the buffer will contain '(ptrval)' instead.
>>> This patch adds a call to wait_for_random_bytes() before plain 'p' tests
>>> to make sure the crng is initialized.
>>
>> Hmm, my system did not boot with this patch and
>> CONFIG_TEST_PRINTF=y
> 
> And neither does my test box. It killed my tests I was running, as one of the
> configs I test has this set.
> 
> It appears that Andrew pulled it in and sent it to Linus, as it is in
> 4.18-rc1, and I need to now revert this patch to make my tests work.

This patch has been superseded with a v2 and a v3 pushed into Petr 
printk.git tree 
(https://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk.git/commit/?h=for-4.19&id=ce041c43f22298485122bab15c14d062383fbc67). 
Sorry for the mess...

Regards,
Thierry

> 
> -- Steve
> 
> 
>>
>> I guess that there was not enough entropy. It is basically a deadlock.
>> The build-in module init calls are called when SMP is enabled but
>> there is no real activity and the init calls are called sequentially.
>> Therefore there is nothing that could produce some entropy, ...
>>
>> I suggest to skip the test when crng is not ready.
>>
>> Best Regards,
>> Petr
>>
>>> Signed-off-by: Thierry Escande <thierry.escande@linaro.org>
>>> Acked-by: Tobin C. Harding <me@tobin.cc>
>>> ---
>>>   lib/test_printf.c | 7 +++++++
>>>   1 file changed, 7 insertions(+)
>>>
>>> diff --git a/lib/test_printf.c b/lib/test_printf.c
>>> index 71ebfa43ad05..839be9385a8a 100644
>>> --- a/lib/test_printf.c
>>> +++ b/lib/test_printf.c
>>> @@ -260,6 +260,13 @@ plain(void)
>>>   {
>>>   	int err;
>>>   
>>> +	/*
>>> +	 * Make sure crng is ready. Otherwise we get "(ptrval)" instead
>>> +	 * of a hashed address when printing '%p' in plain_hash() and
>>> +	 * plain_format().
>>> +	 */
>>> +	wait_for_random_bytes();
>>> +
>>>   	err = plain_hash();
>>>   	if (err) {
>>>   		pr_warn("plain 'p' does not appear to be hashed\n");
>>> -- 
>>> 2.14.1
>>>

  reply	other threads:[~2018-06-22 21:50 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-04 11:37 Thierry Escande
2018-06-05 12:43 ` Andy Shevchenko
2018-06-07 12:24 ` Petr Mladek
2018-06-07 18:47   ` Thierry Escande
2018-06-08  8:04     ` Petr Mladek
2018-06-08  9:07       ` Thierry Escande
2018-06-08  9:46         ` Andy Shevchenko
2018-06-08 10:32           ` Thierry Escande
2018-06-08 11:22             ` Petr Mladek
2018-06-08 11:28               ` Thierry Escande
2018-06-22 20:53   ` Steven Rostedt
2018-06-22 21:50     ` Thierry Escande [this message]
2018-06-25  7:50       ` Petr Mladek
2018-06-25 12:04         ` Petr Mladek

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=a2f0729c-593e-b747-a22f-6468ea88882e@linaro.org \
    --to=thierry.escande@linaro.org \
    --cc=akpm@linux-foundation.org \
    --cc=andy.shevchenko@gmail.com \
    --cc=davem@davemloft.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@rasmusvillemoes.dk \
    --cc=me@tobin.cc \
    --cc=pmladek@suse.com \
    --cc=rostedt@goodmis.org \
    --cc=torvalds@linux-foundation.org \
    --subject='Re: [PATCH RESEND] lib/test_printf.c: call wait_for_random_bytes() before plain %p tests' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).