linux-kernel - Re: [PATCH 1/4] PM/Freezer: Make thaw_processes() thaw only userspace tasks

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Message-ID: <4F271849.302@linux.vnet.ibm.com>
Date:	Tue, 31 Jan 2012 03:53:05 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	Tejun Heo <tj@...nel.org>
CC:	rjw@...k.pl, pavel@....cz, len.brown@...el.com,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] PM/Freezer: Make thaw_processes() thaw only userspace
 tasks

On 01/31/2012 03:39 AM, Tejun Heo wrote:

> On Tue, Jan 31, 2012 at 03:34:57AM +0530, Srivatsa S. Bhat wrote:
>> Currently the situation is:
>>
>> freeze_processes() - freezes only userspace tasks
>> freeze_kernel_threads() - freezes only kernel threads
>> thaw_kernel_threads() - thaws only kernel threads
>> thaw_processes() - thaws *everything* (both userspace tasks and kernel threads)
>>
>> The point that thaw_processes() thaws everything is rather unintuitive
>> and can lead to bugs. So, modify thaw_processes() so that it thaws only
>> userspace processes. This way we can also have more control over what
>> exactly gets thawed in different situations.
>>
>> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
> 
> Maybe I'm misreading it but doesn't this introduce window where kernel
> tasks aren't thawed between this patch and the following ones?  It
> looks like this one should come later.
> 


Yes, I was aware that it introduces such a window. But I ignored it in the
interest of making the patch series sensible (as in, for example, patch
2/4 wouldn't make much sense without patch 1/4).
Maybe I will interchange patch 1 and patch 2 and just reword the patch
descriptions suitably so that they still make sense..

Thanks a lot!

Regards,
Srivatsa S. Bhat

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