RE: [patch 0/4] Take care of cpufreq lockdep issues (take 2)

From: Pallipadi, Venkatesh
Date: Fri Jul 03 2009 - 10:28:48 EST




>-----Original Message-----
>From: Ingo Molnar [mailto:mingo@xxxxxxx]
>Sent: Thursday, July 02, 2009 11:54 PM
>To: Pallipadi, Venkatesh
>Cc: Dave Jones; linux-kernel@xxxxxxxxxxxxxxx;
>cpufreq@xxxxxxxxxxxxxxx; kernel-testers@xxxxxxxxxxxxxxx;
>Rafael J. Wysocki; Dave Young; Pekka Enberg; Mathieu
>Desnoyers; Thomas Renninger
>Subject: Re: [patch 0/4] Take care of cpufreq lockdep issues (take 2)
>
>
>* venkatesh.pallipadi@xxxxxxxxx <venkatesh.pallipadi@xxxxxxxxx> wrote:
>
>> Since recent chanegs to ondemand and conservative governor, there
>> have been multiple reports of lockdep issues in cpufreq. Patch
>> series takes care of these problems.
>>
>> This is the next attempt following the one here, which was not a
>> complete fix.
>> http://lkml.indiana.edu/hypermail/linux/kernel/0906.3/01073.html
>>
>> I am currently running some stress tests to make sure there are no
>> issues with these patches. But, wanted to send them out for
>> review/comments/testing before I head out for the long weekend.
>>
>> If this patchset seems sane, the first patch in the patchset
>> should also get into 30.stable.
>
>Btw., FYI, because my test-systems were frequently triggering those
>bugs, i kept testing the following series from you and Mathieu in
>-tip:
>
> ecf8b04: cpufreq: Define dbs_mutex purpose and cleanup its
>usage conservative gov
> b08c597: cpufreq: Define dbs_mutex purpose and cleanup its usage
> 0807e30: cpufreq: remove rwsem lock from CPUFREQ_GOV_STOP
>call (second call site)
>
>So that fix-series, while probably not complete (given that you sent
>a v2 series), worked well in practice and gets my:
>
> Tested-by: Ingo Molnar <mingo@xxxxxxx>
>
>Is the delta between this (tested) series and your v2 version
>significant? If not it might make sense to shape it as a delta patch
>to the v1 series, if that looks clean enough - to preserve testing
>results.
>

Thanks for testing. That earlier version even though it took care
of lockdep complaints, did not address all the race conditions properly.
The delta is significant as I had to change the approach compared
to first patchset. So, diff will not be very clean.

Thanks,
Venki--
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