linux-kernel - Re: [PATCH RESEND] lib/test_printf.c: call wait_for_random

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Date:   Fri, 8 Jun 2018 12:32:33 +0200
From:   Thierry Escande <thierry.escande@...aro.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Miller <davem@...emloft.net>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        "Tobin C . Harding" <me@...in.cc>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND] lib/test_printf.c: call wait_for_random_bytes()
 before plain %p tests

On 08/06/2018 11:46, Andy Shevchenko wrote:
> On Fri, Jun 8, 2018 at 12:07 PM, Thierry Escande
> <thierry.escande@...aro.org> wrote:
> 
>> But as I type I realize it's not necessary. I will simply enclose the call
>> to wait_for_random_bytes() by #if IS_MODULE() #endif so it gets called only
>> if built as a module, which is how run_kselftest.sh wants it... If
>> test_printf is compiled built-in and the crng is not yet initialized the
>> test will fail anyway so there is no need to add an extra check.
> 
> Unfortunately I can't support this as is.
> We have environments where crng will be ready minutes after the boot.
> It's unacceptable.
> 
> So, we need to have means to not delay test for so long.

I agree we can't delay test execution for too long. In my case the crng 
is ready only a few seconds after the boot. So we may just skip this 
plain 'p' printf test if crng is not ready then.

Regards,
Thierry