linux-kernel - Re: Regression due to 7ff9554 "printk: convert byte-buffer to variable-length record buffer"

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Date:	Thu, 10 May 2012 22:06:42 +0200
From:	Kay Sievers <kay@...y.org>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	William Douglas <william.douglas@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-next@...r.kernel.org
Subject: Re: Regression due to 7ff9554 "printk: convert byte-buffer to
 variable-length record buffer"

On Thu, May 10, 2012 at 9:54 PM, Stephen Warren <swarren@...dotorg.org> wrote:
> On 05/09/2012 12:31 PM, Stephen Warren wrote:
>> For me, next-20120508 prints nothing when booted, and I think also
>> hangs. To solve this, I reverted:
>>
>> 7ff9554 printk: convert byte-buffer to variable-length record buffer
>>
>> In order to build, I also had to revert:
>>
>> c4e00da driver-core: extend dev_printk() to pass structured data
>>
>> Note: I'm running on an ARM system using a serial console, with
>> earlyprintk enabled.
>
> This issue still occurs in next-20120510.
>
> I've tracked it down to the assignment of msg->ts_nsec near the end of
> log_store(). If I comment this out, everything works. The problem is the
> assignment, not the call to local_clock():
>
> fails:
>        msg->ts_nsec = local_clock();
> fails:
>        msg->ts_nsec = 0;//local_clock();
> works:
>        //msg->ts_nsec = local_clock();

Weird.

What happens if you change it to:
  cpu_clock(logbuf_cpu);
?

If it works, the timestamps look ok?

Kay
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