[PATCH v2 1/2] mailbox: cix: validate fast channel index before request_irq()

[kr494167@gmail.com]

From: Surendra Singh Chouhan <kr494167@gmail.com>

cix_mbox_startup() checked fast channel index constraints (index < 0 ||
index > CIX_MBOX_FAST_IDX) inside the channel switch block after
calling request_irq(). If validation failed, it triggered a free_irq()
cleanup path.

Validating channel parameters prior to request_irq() avoids unnecessary
IRQ registration and teardown churn.

Signed-off-by: Surendra Singh Chouhan <kr494167@gmail.com>
---
 drivers/mailbox/cix-mailbox.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/mailbox/cix-mailbox.c b/drivers/mailbox/cix-mailbox.c
index 43c76cdab24a..615218c69eeb 100644
--- a/drivers/mailbox/cix-mailbox.c
+++ b/drivers/mailbox/cix-mailbox.c
@@ -403,6 +403,13 @@ static int cix_mbox_startup(struct mbox_chan *chan)
 	int index = cp->index, ret;
 	u32 val;
 
+	if (cp->type == CIX_MBOX_TYPE_FAST && priv->dir == CIX_MBOX_RX) {
+		if (index < 0 || index > CIX_MBOX_FAST_IDX) {
+			dev_err(priv->dev, "Invalid index %d\n", index);
+			return -EINVAL;
+		}
+	}
+
 	ret = request_irq(priv->irq, cix_mbox_isr, IRQF_NO_SUSPEND,
 			  dev_name(priv->dev), chan);
 	if (ret) {
@@ -448,11 +455,6 @@ static int cix_mbox_startup(struct mbox_chan *chan)
 	case CIX_MBOX_TYPE_FAST:
 		/* Only RX channel has intterupt */
 		if (priv->dir == CIX_MBOX_RX) {
-			if (index < 0 || index > CIX_MBOX_FAST_IDX) {
-				dev_err(priv->dev, "Invalid index %d\n", index);
-				ret = -EINVAL;
-				goto failed;
-			}
 			/* enable fast channel interrupt */
 			val = cix_mbox_read(priv, CIX_INT_ENABLE_SIDE_B);
 			val |= CIX_FAST_CH_INT(index);
@@ -461,14 +463,10 @@ static int cix_mbox_startup(struct mbox_chan *chan)
 		break;
 	default:
 		dev_err(priv->dev, "Invalid channel type: %d\n", cp->type);
-		ret = -EINVAL;
-		goto failed;
+		free_irq(priv->irq, chan);
+		return -EINVAL;
 	}
 	return 0;
-
-failed:
-	free_irq(priv->irq, chan);
-	return ret;
 }
 
 static void cix_mbox_shutdown(struct mbox_chan *chan)
-- 
2.55.0