RE: FUSYN and RT

[Daniel Walker <dwalker@mvista.com>]

On Wed, 2005-04-13 at 08:46, Steven Rostedt wrote:
> How hard would it be to use the RT mutex PI for the priority inheritance
> for fusyn?  I only work with the RT mutex now and haven't looked at the
> fusyn.  Maybe Ingo can make a separate PI system with its own API that
> both the fusyn and RT mutex can use. This way the fusyn locks can still
> be separate from the RT mutex locks but still work together. 
> 
> Basically can the fusyn work with the rt_mutex_waiter?  That's what I
> would pull into its own subsystem.  Have another structure that would
> reside in both the fusyn and RT mutex that would take over for the
> current rt_mutex that is used in pi_setprio and task_blocks_on_lock in
> rt.c.  So if both locks used the same PI system, then this should all be
> cleared up. 
> 
> If this doesn't makes sense, or just confusing, I'll explain more :-)  

I've thought about this as an option, but when I first started this
thread It seemed like the two could work independently, and safely which
doesn't appear to be the case any more.

The problems with pulling out the PI in the RT mutex are that
pi_setprio() does a walk over lock->owner and we're got two different
lock structures now . I was thinking we could add something like
lock_ops (get_owner(), wait_list_add(), wait_list_del(), ?? ) to
rt_mutex_waiter, or abstract rt_lock. Then pi_setprio would just use the
lock_ops instead of accessing a structure .. 

I've only gone over the Fusyn code briefly , so I'm assuming all this
could be added.  I think it's a safe assumption though .

Daniel