Replace i386/x86_64 nmi_callback RCU code with atomic notifier chain

Replace i386/x86_64 nmi_callback RCU code with atomic notifier chain

[Keith Owens]

i386 and x86_64 have low level RCU code to handle dynamic registration
and unregistration of the NMI callback function.  With the rewrite of
the general notifier chains, we can remove the low level RCU hacking
from these NMI handlers and replace them with an atomic notifier chain,
making the code much simpler.  set_nmi_callback() gets replaced by yet
another notify chain.  The only affected code outside the main NMI
handler is crash and oprofile.  Any objections?

Re: Replace i386/x86_64 nmi_callback RCU code with atomic notifier chain

[Andi Kleen]

On Thursday 18 May 2006 08:17, Keith Owens wrote:
> i386 and x86_64 have low level RCU code to handle dynamic registration
> and unregistration of the NMI callback function.  With the rewrite of
> the general notifier chains, we can remove the low level RCU hacking
> from these NMI handlers and replace them with an atomic notifier chain,
> making the code much simpler.  set_nmi_callback() gets replaced by yet
> another notify chain.  The only affected code outside the main NMI
> handler is crash and oprofile.  Any objections?

It has been already done. Check -mm or firstfloor tree. However I don't 
know if the module unload case is fully correct. If you find holes
feel free to submit patches for that.

But normally just for module unloading you don't need individual
RCU because the module unloader does a stop_machine() and that
blocks out most thing.

-Andi

Re: Replace i386/x86_64 nmi_callback RCU code with atomic notifier chain

[Keith Owens]

Andi Kleen (on Thu, 18 May 2006 12:15:27 +0200) wrote:
>On Thursday 18 May 2006 08:17, Keith Owens wrote:
>> i386 and x86_64 have low level RCU code to handle dynamic registration
>> and unregistration of the NMI callback function.  With the rewrite of
>> the general notifier chains, we can remove the low level RCU hacking
>> from these NMI handlers and replace them with an atomic notifier chain,
>> making the code much simpler.  set_nmi_callback() gets replaced by yet
>> another notify chain.  The only affected code outside the main NMI
>> handler is crash and oprofile.  Any objections?
>
>It has been already done. Check -mm or firstfloor tree.

Where is this 'firstfloor' tree?  The only google references are to
http://www.firstfloor.org/~andi which gives "You don't have permission
to access /~andi/ on this server".  Google also lists ~andi/35,
~andi/softnet/, ~andi/numa.html, ~andi/mbind.html, but they all get 404
errors.

Re: Replace i386/x86_64 nmi_callback RCU code with atomic notifier chain

[Andi Kleen]

> Where is this 'firstfloor' tree?  The only google references are to
> http://www.firstfloor.org/~andi which gives "You don't have permission
> to access /~andi/ on this server".  Google also lists ~andi/35,
> ~andi/softnet/, ~andi/numa.html, ~andi/mbind.html, but they all get 404
> errors.

ftp://ftp.firstfloor.org/pub/ak/x86_64/quilt/

It's the staging tree for x86-64 and some i386 merges
It's also mirrored into -mm* with some lag.

-Andi