[PATCH v2 4/4] cxl/events: Return IRQ_NONE when no events were processed

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

cxl_event_thread() returns IRQ_HANDLED whether or not it found
anything to do. Claiming every interrupt as handled means a device
flooding its MSI vector is never detected.

Return IRQ_NONE unless the Event Status register names a log to drain.

Fixes: a49aa8141b65 ("cxl/mem: Wire up event interrupts")
Signed-off-by: Anisa Su <anisa.su@samsung.com>
---
 drivers/cxl/pci.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 239df18c9c87..94ff2b7d1f09 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -528,6 +528,7 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
 	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
 	u32 mask = CXLDEV_EVENT_STATUS_ALL;
 	int attempts = CXL_EVENT_DRAIN_ATTEMPTS;
+	bool handled = false;
 
 	while (mask) {
 		u32 status, drained, stuck;
@@ -542,6 +543,7 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
 		status &= mask;
 		if (!status)
 			break;
+		handled = true;
 
 		rc = cxl_mem_get_event_records(mds, status, &drained);
 		if (rc) {
@@ -579,7 +581,7 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
 		cond_resched();
 	}
 
-	return IRQ_HANDLED;
+	return handled ? IRQ_HANDLED : IRQ_NONE;
 }
 
 static int cxl_event_req_irq(struct cxl_dev_state *cxlds, u8 setting)
-- 
2.43.0