Messages in this thread | | | Date | Tue, 10 Apr 2012 22:56:54 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: CPU Hotplug rework |
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On 04/10/2012 09:16 PM, Paul E. McKenney wrote:
> On Tue, Apr 10, 2012 at 07:11:50PM +0530, Srivatsa S. Bhat wrote:
[This is a quick reply to give the links you requested. I'll reply to the other things after I read what you wrote more thoroughly.]
>> Why does my approach help? > > At this point, I must confess that I have lost track of exactly what > your approach is...
The same old "incomplete" patchset ;-) (Note that the patch 1/3 is complete. The "incomplete" tag is just because it is followed by changes only to powerpc (2/3) and sparc (3/3), while actually, many other places need to be changed. But the first patch in the series is definitely in full form.
https://lkml.org/lkml/2012/3/1/39 https://lkml.org/lkml/2012/3/1/40 https://lkml.org/lkml/2012/3/1/41
> >> It ensures that do_setup() will never occur in parallel with CPU hotplug, >> at any time. Hence the individual notifiers need not watch their back - >> they can continue to be non-reentrant and still everything will work fine >> because we fix it at the callback registration level itself. >> >> Honestly, I wrote this patchset to fix issues opened up by the async booting >> patch[1]. That patch caused boot failures in powerpc [2] because of CPU >> Hotplug notifier races. And I believe the solution I proposed will fix it. >> >> Without the async booting patch, this was more or less a theoretical race. >> That patch made it not only real but also severe enough to cause boot >> failures. >> >> So, if the async booting design is not being pushed any further, then I >> guess we can simply ignore this theoretical race altogether and focus on >> more important issues (I am totally OK with that) ... and possibly revisit >> this race whenever it bites us again ;-) >> >> What do you think? >> >> [1]. http://thread.gmane.org/gmane.linux.kernel/1246209 >> [2]. http://thread.gmane.org/gmane.linux.kernel.next/20726/focus=20757 > > Neither of the above two URLs points to a patch,
?? Well, the first one points to the async booting patch and the second one points to a verbal root-cause analysis of the boot failure on powerpc, caused by that patch.
Let me give equivalent links from lkml.org: [1]. https://lkml.org/lkml/2012/1/31/286 [2]. https://lkml.org/lkml/2012/2/13/383
Regards, Srivatsa S. Bhat
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