[RFC 01/14] drm/xe: Make exec_queue_kill safe to call twice

[Matthew Brost]

On Fri, Jul 12, 2024 at 03:22:43PM -0700, Daniele Ceraolo Spurio wrote:
> 
> 
> On 7/12/2024 3:11 PM, Matthew Brost wrote:
> > On Fri, Jul 12, 2024 at 02:28:45PM -0700, Daniele Ceraolo Spurio wrote:
> > > An upcoming PXP patch will kill queues at runtime when a PXP
> > > invalidation event occurs, so we need exec_queue_kill to be safe to call
> > > multiple times.
> > > 
> > > Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> > > Cc: Matthew Brost <matthew.brost at intel.com>
> > Not opposed this patch but is this really required for PXP as PXP queue
> > are not in LR mode are they?
> > 
> > Either way, I'm open to accepting this as xe_exec_queue_kill probably
> > should be safe to call twice anyways.
> 
> Not required for PXP, no. I just really didn't like the idea of calling a
> function twice when it wasn't designed to support multiple calls, even if it
> didn't apply to my specific case.
> 

Fair enough, I think go ahead and send this out by itself with:
Reviewed-by: Matthew Brost <matthew.brost at intel.com>

Maybe add some kernel doc to xe_exec_queue_kill too if have time
mentioning it is safe to call twice.  

> Daniele
> 
> > 
> > Matt
> > 
> > > ---
> > >   drivers/gpu/drm/xe/xe_vm.c | 6 ++++--
> > >   1 file changed, 4 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> > > index 5b166fa03684..02f684c0330d 100644
> > > --- a/drivers/gpu/drm/xe/xe_vm.c
> > > +++ b/drivers/gpu/drm/xe/xe_vm.c
> > > @@ -280,8 +280,10 @@ void xe_vm_remove_compute_exec_queue(struct xe_vm *vm, struct xe_exec_queue *q)
> > >   		return;
> > >   	down_write(&vm->lock);
> > > -	list_del(&q->lr.link);
> > > -	--vm->preempt.num_exec_queues;
> > > +	if (!list_empty(&q->lr.link)) {
> > > +		list_del_init(&q->lr.link);
> > > +		--vm->preempt.num_exec_queues;
> > > +	}
> > >   	if (q->lr.pfence) {
> > >   		dma_fence_enable_sw_signaling(q->lr.pfence);
> > >   		dma_fence_put(q->lr.pfence);
> > > -- 
> > > 2.43.0
> > > 
>