[PATCH] firmware: arm_scmi: rate-limit queue-full warnings in IRQ context

[PATCH] firmware: arm_scmi: rate-limit queue-full warnings in IRQ context

[Pushpendra Singh]

The scmi_notify() function is called from interrupt context
to queue received notification events onto a per-protocol
kfifo. When the kfifo is full, it logs a warning via dev_warn()
for every dropped event.

Under conditions where the platform sends a burst of SCMI
notifications faster than the deferred worker can drain the
queue, this results in a flood of dev_warn() calls from
IRQ context. Each call acquires the console lock and may
execute blocking console writes, causing the CPU to be held
in interrupt context for an extended period and leading to
observable system stalls.

Fix this by switching to dev_warn_ratelimited() to limit the
frequency of log messages when the notification queue is full.
This reduces console overhead in interrupt context and prevents
CPU stalls caused by excessive logging, while still preserving
diagnostic visibility.

Signed-off-by: Pushpendra Singh <pushpendra.singh@oss.qualcomm.com>
---
 drivers/firmware/arm_scmi/notify.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_scmi/notify.c b/drivers/firmware/arm_scmi/notify.c
index 40ec184eedae..574f368033ae 100644
--- a/drivers/firmware/arm_scmi/notify.c
+++ b/drivers/firmware/arm_scmi/notify.c
@@ -600,7 +600,7 @@ int scmi_notify(const struct scmi_handle *handle, u8 proto_id, u8 evt_id,
 		return -EINVAL;
 	}
 	if (kfifo_avail(&r_evt->proto->equeue.kfifo) < sizeof(eh) + len) {
-		dev_warn(handle->dev,
+		dev_warn_ratelimited(handle->dev,
 			 "queue full, dropping proto_id:%d  evt_id:%d  ts:%lld\n",
 			 proto_id, evt_id, ktime_to_ns(ts));
 		return -ENOMEM;
-- 
2.34.1