Re: [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending

[Shaikh Kamaluddin]

On Wed, Sep 16, 2026 at 09:38:37AM +0900, Anisa Su wrote:
> On Sat, Sep 12, 2026 at 03:08:15PM +0530, Shaikh Kamaluddin wrote:
> > CXL event interrupts may share an MSI/MSI-X vector with other event
> > logs or device features. Consequently, cxl_event_thread() is registered
> > with IRQF_SHARED and must determine whether the event-log facility
> > claimed the interrupt.
> > 
> > The handler masks the Device Event Status register to the event logs
> > supported by the driver. However, when no supported status bit is set,
> > it exits the processing loop and still returns IRQ_HANDLED. This
> > incorrectly reports that the interrupt was claimed and prevents the
> > generic spurious-interrupt detector from accounting it as unhandled.
> > 
> > Track whether the CXL event handler claimed the interrupt and return
> > IRQ_NONE when no supported event is detected. If no handler sharing the
> > vector claims a sustained interrupt storm, the generic spurious-
> > interrupt detector can eventually identify and disable the affected
> > IRQ.
> > 
> > Signed-off-by: Shaikh Kamaluddin <shaikhkamal2012@xxxxxxxxx>
> Reviewed-by: Anisa Su <anisa.su@xxxxxxxxxxx>
> > ---
> > Changes in V2:
> > - Emphasize that returning IRQ_NONE enables generic spurious-interrupt
> >   detection and drop the Fixes tag. (Jonathan Cameron)
> > - Check whether the event interrupt is already disabled by Anisa Su's
> >   patch; no code changes were needed. (Ben Cheatham)
> 
> One thing I want to correct: The change requested was to say a
> spurious IRQ will eventually be disabled in the commit message, not
> check whether the event interrupts is already disabled...
> See https://lore.kernel.org/linux-cxl/aqLZP3ORYzCLfSgR@acer-nitro-anv15-41/T/#m32c74ebf05eee9a3ee49c57dd24848db29919031
> I do see that it's been added to the commit message though, so no need
> to do anything.
>

Hi Anisa,

I got your point, yes commit message already covered this.

Thanks,
Shaikh 

> Thanks,
> Anisa
> > - Rebase onto v7.3-rc2; no code changes.
> > 
> >  drivers/cxl/pci.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> > index c7c91e8dc51d..8b560cae91f2 100644
> > --- a/drivers/cxl/pci.c
> > +++ b/drivers/cxl/pci.c
> > @@ -515,6 +515,7 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> >  	struct cxl_dev_id *dev_id = id;
> >  	struct cxl_dev_state *cxlds = dev_id->cxlds;
> >  	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
> > +	bool handled = false;
> >  	u32 status;
> >  
> >  	do {
> > @@ -527,11 +528,13 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> >  		status &= CXLDEV_EVENT_STATUS_ALL;
> >  		if (!status)
> >  			break;
> > +
> > +		handled = true;
> >  		cxl_mem_get_event_records(mds, status);
> >  		cond_resched();
> >  	} while (status);
> >  
> > -	return IRQ_HANDLED;
> > +	return handled ? IRQ_HANDLED : IRQ_NONE;
> >  }
> >  
> >  static int cxl_event_req_irq(struct cxl_dev_state *cxlds, u8 setting)
> > 
> > base-commit: df2908090cda368b01ff43709f51890076c56157
> > -- 
> > 2.43.0
> >