On Fri, Aug 29, 2014 at 02:01:00PM +0200, David Herrmann wrote:
> There is no reason to use a heavy mutex for idr protection. Use a spinlock
> and make idr-allocation use idr_preload().
> 
> This patch also makes mode-object lookup irq-save, in case you ever wanna
> lookup modeset objects from interrupts. This is just a side-effect of
> avoiding a mutex.

I don't think that's entirely accurate. idr_preload(GFP_KERNEL) might
sleep since GFP_KERNEL & __GFP_WAIT != 0.

Thierry