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

[Anisa Su <anisa.su887@gmail.com>]

On Sun, Sep 06, 2026 at 09:27:05PM +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 an interrupt belongs to the
> event-log facility.
> 
> 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.
> 
> Track whether at least one supported event status bit was observed.
> Return IRQ_NONE when there was no event to service, while continuing to
> return IRQ_HANDLED after processing one or more event logs.
> 
> Fixes: a49aa8141b65 ("cxl/mem: Wire up event interrupts")
> 
> Signed-off-by: Shaikh Kamaluddin <shaikhkamal2012@gmail.com>
Hello,

This looks similar to a patch I sent last week:
[PATCH v2 4/4] cxl/events: Return IRQ_NONE when no events were processed
https://lore.kernel.org/linux-cxl/8e22c1c2-8098-492a-8162-3dd27507c853@amd.com/T/#ma4cf2b2dddaeebc06cb73f81647817bdbb51963c

It was dropped because I received the feedback that in general, the driver does
not need to handle device-side errors/spec-violating behaviors. I believe it
would apply here as well. But if I misunderstood the intent of this patch,
let me know.

Thanks,
Anisa
> ---
>  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: 7098e9cd98a05c0c5de2fae0c2465f9d966fdd07
> prerequisite-patch-id: 92e40cd60a697020faac475dcc77ba63b33434ea
> prerequisite-patch-id: 10027ad5d9aed85806047f807b3a76273b6c4a77
> -- 
> 2.43.0
>