Change ia64 mca sysctls to use standard dynamic sysctls

[Marcel Moolenaar]

On Feb 3, 2009, at 8:07 AM, John Baldwin wrote:

> On Monday 02 February 2009 7:59:11 pm Marcel Moolenaar wrote:
>>
>> On Feb 2, 2009, at 10:44 AM, John Baldwin wrote:
>>
>>> While working on the locking for the sysctl tree, I ran into the
>>> pseudo-dynamic machine check sysctls in ia64.  It is not really a
>>> good idea
>>> to call sysctl_register_oid() with a spin lock held and once I add
>>> locking to
>>> sysctl it becomes a bad LOR.  This changes the code to use the
>>> public API for
>>> adding dynamic sysctls outside of the spin lock.  Please test this
>>> as it is a
>>> prerequisite for finishing the locking of the sysctl tree.
>>
>> This won't be a solution, because eventually this code gets called
>> for machine checks, which means that locks can be held (which is
>> then the least of our worries :-)
>>
>> In any case: malloc(M_WAITOK) cannot be used. We should probably
>> delay updating the sysctl tree and do it in a more controlled
>> environment. If you can implement a simple linked list to store
>> the saved state and remove the call to SYSCTL_ADD_OID, then I'll
>> work on that part after you're done. Does that sound like a plan?
>
> Ok.  Checking for failures from M_NOWAIT is important, too. :)  Here's
> an updated patch that uses the queue.  I haven't implemented the stuff
> to schedule calls to the populate routine to drain the queue though.
> Would you be able to do that?

Yes, I will. Getting everything right takes some careful
testing and probably requires deliberate error injection.
I can't ask that of you :-)

-- 
Marcel Moolenaar
xcllnt at mac.com