Re: [PATCH v6 6/9] drm/panthor: Protect events processing with a separate spinlock

[Boris Brezillon <boris.brezillon@collabora.com>]

On Mon, 17 Aug 2026 16:21:25 +0100
Steven Price <steven.price@arm.com> wrote:

> > +	/**
> > +	 * @events_lock: Lock taken when processing events.
> > +	 *
> > +	 * This also needs to be taken when csg_slots are updated, to make sure
> > +	 * the event processing logic doesn't touch groups that have left the CSG
> > +	 * slot.
> > +	 */
> > +	spinlock_t events_lock;
> > +
> >  	/**
> >  	 * @csg_slots: FW command stream group slots.
> > +	 *
> > +	 * Updates to these slots must happen with both panthor_scheduler::lock and
> > +	 * panthor_scheduler::events_lock held. As a result, reads can happen with
> > +	 * either of these locks held.  
> 
> Technically this isn't quite true - priority can be changed with only
> sched->lock. Perhaps the following would be slightly more accurate wording?
> 
>    * Updates to the group binding must happen with both
>    * panthor_scheduler::lock and panthor_scheduler::events_lock held.
>    * The group binding may therefore be read while holding either lock.
>    * Other slot fields are protected by panthor_scheduler::lock.


I'll go for your suggestion in v7.