[PATCH 6.18 51/60] Input: rmi4 - iterative IRQ handler

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>

commit b6ca982afd0e8fbcbb340092d3c6d3b4a217686c upstream.

The current IRQ handler uses recursion to drain the attention FIFO,
which can lead to stack overflow on deep queues. Convert it to a
loop.

Fixes: b908d3cd812a ("Input: synaptics-rmi4 - allow to add attention data")
Cc: stable@vger.kernel.org
Assisted-by: Gemini:gemini-3.1-pro
Link: https://patch.msgid.link/20260505045952.1570713-6-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/input/rmi4/rmi_driver.c |   32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

--- a/drivers/input/rmi4/rmi_driver.c
+++ b/drivers/input/rmi4/rmi_driver.c
@@ -198,24 +198,24 @@ static irqreturn_t rmi_irq_fn(int irq, v
 	struct rmi4_attn_data attn_data = {0};
 	int ret, count;
 
-	count = kfifo_get(&drvdata->attn_fifo, &attn_data);
-	if (count) {
-		*(drvdata->irq_status) = attn_data.irq_status;
-		drvdata->attn_data = attn_data;
-	}
+	do {
+		count = kfifo_get(&drvdata->attn_fifo, &attn_data);
+		if (count) {
+			*drvdata->irq_status = attn_data.irq_status;
+			drvdata->attn_data = attn_data;
+		}
 
-	ret = rmi_process_interrupt_requests(rmi_dev);
-	if (ret)
-		rmi_dbg(RMI_DEBUG_CORE, &rmi_dev->dev,
-			"Failed to process interrupt request: %d\n", ret);
+		ret = rmi_process_interrupt_requests(rmi_dev);
+		if (ret)
+			rmi_dbg(RMI_DEBUG_CORE, &rmi_dev->dev,
+				"Failed to process interrupt request: %d\n",
+				ret);
 
-	if (count) {
-		kfree(attn_data.data);
-		drvdata->attn_data.data = NULL;
-	}
-
-	if (!kfifo_is_empty(&drvdata->attn_fifo))
-		return rmi_irq_fn(irq, dev_id);
+		if (count) {
+			kfree(attn_data.data);
+			drvdata->attn_data.data = NULL;
+		}
+	} while (!kfifo_is_empty(&drvdata->attn_fifo));
 
 	return IRQ_HANDLED;
 }