Messages in this thread | | | Subject | Re: Linux 2.6.17-rc2 - notifier chain problem? | From | Chandra Seetharaman <> | Date | Wed, 26 Apr 2006 13:21:33 -0700 |
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On Wed, 2006-04-26 at 12:29 -0700, Ashok Raj wrote: > On Wed, Apr 26, 2006 at 11:43:48AM -0700, Andrew Morton wrote: > > Chandra Seetharaman <sekharan@us.ibm.com> wrote: > > Ashok's the one who has spent most time with this. Basically _everything_ > > to do with register_cpu_notifier() and all the things which call it should > > be __cpuinit and should be tossed away during boot on non-cpu-hotplug > > kernels. > > > > But there are a few nasty problems with that which made us give up. > > I think we got to a reasonable start, until i got busy with other things > and didnt complete it all the way to be ready to submit. There were many files > that got affected, so we thought may be could take smaller steps. > > for the above xfs, if you want to avoid the ifdef CONFIG_HOTPLUG_CPU > you could choose to use the hotcpu_notifier() which is null macro when > CONFIG_HOTPLUG_CPU=n
No, they can't use the hotcpu_notifier, because they want to hold on to their notifier block (as they attach it with each mount data structure).
But, it is not a major issue. Changes to xfs to adhere to the model being discussed is very small.
> > The problem we ran into was some of the startup code depends on the notifier > call chain for smp bringup, hence we couldn't nuke it similar to > hotcpu_notifier().
I do not understand the problem. If everybody that uses register_cpu_notifier() starts using __cpuinit and __cpuinitdata (or the devinit siblings), then the notifier mechanism will not be any different than what they are now, right ? (both in hotplug cpu and non-hotplug cpu case) Or am i missing something ?
> > so we ended up calling that function for early risers as > early_register_cpu_notifier(), and all functions/data with __cpuinit etc to > overcome that issue. > > I will try to pursue to again when i get a chance.
I made patches that removes all init stuff from all the usages of notifier_blocks, and i _think_ it is on its way to 2.6.17. The question is, should it go in or not ?
May be the right answer is it should not and xfs should fix their register_cpu_notifier() usage.
chandra --
---------------------------------------------------------------------- Chandra Seetharaman | Be careful what you choose.... - sekharan@us.ibm.com | .......you may get it. ----------------------------------------------------------------------
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