linux-kernel - Re: [PATCH] tracing: Merge separate resize loops

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Date:	Fri, 18 May 2012 20:00:38 -0700
From:	Vaibhav Nagarnaik <vnagarnaik@...gle.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Laurent Chavey <chavey@...gle.com>,
	Justin Teravest <teravest@...gle.com>,
	David Sharp <dhsharp@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tracing: Merge separate resize loops

On Fri, May 18, 2012 at 6:56 PM, Steven Rostedt <rostedt@...dmis.org> wrote:
> On Fri, 2012-05-18 at 13:29 -0700, Vaibhav Nagarnaik wrote:
>>
>>               /* wait for all the updates to complete */
>>               for_each_buffer_cpu(buffer, cpu) {
>>                       cpu_buffer = buffer->buffers[cpu];
>> -                     if (!cpu_buffer->nr_pages_to_update||
>> -                         !cpu_online(cpu))
>> +                     if (!cpu_buffer->nr_pages_to_update)
>>                               continue;
>>
>
> Why did you make this change? As we only need to wait for completions.
>
>> -                     wait_for_completion(&cpu_buffer->update_completion);
>> -                     /* reset this value */
>> +                     if (cpu_online(cpu))
>> +                             wait_for_completion(&cpu_buffer->update_done);
>>                       cpu_buffer->nr_pages_to_update = 0;
>
> Or was the original patch buggy, where we never set nr_page_to_update to
> zero for the offline case?

I don't see a bug, since at the start of the resize operation, we
always recalculate this value. It will be reset to 0, if there are no
updates. I set it to zero at the end just as a precautionary measure.


Vaibhav Nagarnaik
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