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

[Shaikh Kamaluddin <shaikhkamal2012@gmail.com>]

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>
---
 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