[PATCH 1/2] drm: make idr_mutex a spinlock

David Herrmann dh.herrmann at gmail.com
Fri Aug 29 06:11:19 PDT 2014


On Fri, Aug 29, 2014 at 3:10 PM, Thierry Reding
<thierry.reding at gmail.com> wrote:
> 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.

idr_preload() is only used in registration, not in lookups. Not sure
what you refer to?


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