[PATCH 4/8] firmware: arm_ffa: Fix Rx buffer release in fwk notification handler

[Sudeep Holla]

Refactor handle_fwk_notif_callbacks() so that all exit paths funnel
through a single FFA_RX_RELEASE call. While doing that, use scoped_guard()
for the Rx buffer lock and keep the message parsing under the lock scope.

This makes the Rx buffer release explicit for the kmemdup() failure path
and for the early exit when the framework notification bit is not set.

This will ensure the Rx buffer is always release in the framework
notification handler.

Fixes: 285a5ea0f542 ("firmware: arm_ffa: Add support for handling framework notifications")
Signed-off-by: Sudeep Holla <sudeep.holla at kernel.org>
---
 drivers/firmware/arm_ffa/driver.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index 4dec7ca52f8c..764cb1226182 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -1472,25 +1472,21 @@ static void handle_fwk_notif_callbacks(u32 bitmap)
 
 	/* Only one framework notification defined and supported for now */
 	if (!(bitmap & FRAMEWORK_NOTIFY_RX_BUFFER_FULL))
-		return;
+		goto release_rx;
 
-	mutex_lock(&drv_info->rx_lock);
+	scoped_guard(mutex, &drv_info->rx_lock) {
+		msg = drv_info->rx_buffer;
+		buf = kmemdup((void *)msg + msg->offset, msg->size, GFP_KERNEL);
+		if (!buf)
+			goto release_rx;
 
-	msg = drv_info->rx_buffer;
-	buf = kmemdup((void *)msg + msg->offset, msg->size, GFP_KERNEL);
-	if (!buf) {
-		mutex_unlock(&drv_info->rx_lock);
-		return;
+		target = SENDER_ID(msg->send_recv_id);
+		if (msg->offset >= sizeof(*msg))
+			uuid_copy(&uuid, &msg->uuid);
+		else
+			uuid_copy(&uuid, &uuid_null);
 	}
 
-	target = SENDER_ID(msg->send_recv_id);
-	if (msg->offset >= sizeof(*msg))
-		uuid_copy(&uuid, &msg->uuid);
-	else
-		uuid_copy(&uuid, &uuid_null);
-
-	mutex_unlock(&drv_info->rx_lock);
-
 	ffa_rx_release();
 
 	read_lock(&drv_info->notify_lock);
@@ -1500,6 +1496,11 @@ static void handle_fwk_notif_callbacks(u32 bitmap)
 	if (cb_info && cb_info->fwk_cb)
 		cb_info->fwk_cb(notify_id, cb_info->cb_data, buf);
 	kfree(buf);
+
+	return;
+
+release_rx:
+	ffa_rx_release();
 }
 
 static void notif_get_and_handle(void *cb_data)

-- 
2.43.0