dmaengine: idxd: fix device leaks on compat bind and unbind

Make sure to drop the reference taken when looking up the idxd device as
part of the compat bind and unbind sysfs interface.

Fixes: 6e7f3ee ("dmaengine: idxd: move dsa_drv support to compatible mode")
Cc: stable@vger.kernel.org	# 5.15
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251117161258.10679-7-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: jhovold

drivers/dma/idxd/compat.c

@@ -20,11 +20,16 @@ static ssize_t unbind_store(struct device_driver *drv, const char *buf, size_t c
 	int rc = -ENODEV;
 
 	dev = bus_find_device_by_name(bus, NULL, buf);
-	if (dev && dev->driver) {
+	if (!dev)
+		return -ENODEV;
+
+	if (dev->driver) {
 		device_driver_detach(dev);
 		rc = count;
 	}
 
+	put_device(dev);
+
 	return rc;
 }
 static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);
@@ -38,9 +43,12 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t cou
 	struct idxd_dev *idxd_dev;
 
 	dev = bus_find_device_by_name(bus, NULL, buf);
-	if (!dev || dev->driver || drv != &dsa_drv.drv)
+	if (!dev)
 		return -ENODEV;
 
+	if (dev->driver || drv != &dsa_drv.drv)
+		goto err_put_dev;
+
 	idxd_dev = confdev_to_idxd_dev(dev);
 	if (is_idxd_dev(idxd_dev)) {
 		alt_drv = driver_find("idxd", bus);
@@ -53,13 +61,20 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t cou
 			alt_drv = driver_find("user", bus);
 	}
 	if (!alt_drv)
-		return -ENODEV;
+		goto err_put_dev;
 
 	rc = device_driver_attach(alt_drv, dev);
 	if (rc < 0)
-		return rc;
+		goto err_put_dev;
+
+	put_device(dev);
 
 	return count;
+
+err_put_dev:
+	put_device(dev);
+
+	return rc;
 }
 static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);