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 14:09:41 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Kay Sievers <kay@...y.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 05/10/2012 02:06 PM, Kay Sievers wrote:
> 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?

I doubt that would work - after all, assigning 0 fails, but not
performing the assignment at all works. But, I'll go try it...
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