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From:   Matthias Kaehlcke <mka@chromium.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Johan Hovold <johan@kernel.org>, linux-usb@vger.kernel.org,
        Stefan Wahren <stefan.wahren@i2se.com>,
        Alexander Stein <alexander.stein@ew.tq-group.com>,
        Icenowy Zheng <uwu@icenowy.me>,
        Douglas Anderson <dianders@chromium.org>,
        stable@vger.kernel.org, linux-kernel@vger.kernel.org,
        Matthias Kaehlcke <mka@chromium.org>,
        Ravi Chandra Sadineni <ravisadineni@chromium.org>
Subject: [PATCH 1/2] usb: misc: onboard_hub: Invert driver registration order
Date:   Thu,  5 Jan 2023 23:03:28 +0000
Message-Id: <20230105230119.1.I75494ebee7027a50235ce4b1e930fa73a578fbe2@changeid>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The onboard_hub 'driver' consists of two drivers, a platform
driver and a USB driver. Currently when the onboard hub driver
is initialized it first registers the platform driver, then the
USB driver. This results in a race condition when the 'attach'
work is executed, which is scheduled when the platform device
is probed. The purpose of fhe 'attach' work is to bind elegible
USB hub devices to the onboard_hub USB driver. This fails if
the work runs before the USB driver has been registered.

Register the USB driver first, then the platform driver. This
increases the chances that the onboard_hub USB devices are probed
before their corresponding platform device, which the USB driver
tries to locate in _probe(). The driver already handles this
situation and defers probing if the onboard hub platform device
doesn't exist yet.

Cc: stable@vger.kernel.org
Fixes: 8bc063641ceb ("usb: misc: Add onboard_usb_hub driver")
Link: https://lore.kernel.org/lkml/Y6W00vQm3jfLflUJ@hovoldconsulting.com/T/#m0d64295f017942fd988f7c53425db302d61952b4
Reported-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---

 drivers/usb/misc/onboard_usb_hub.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/misc/onboard_usb_hub.c b/drivers/usb/misc/onboard_usb_hub.c
index 94e7966e199d..db0844b30bbd 100644
--- a/drivers/usb/misc/onboard_usb_hub.c
+++ b/drivers/usb/misc/onboard_usb_hub.c
@@ -433,13 +433,13 @@ static int __init onboard_hub_init(void)
 {
 	int ret;
 
-	ret = platform_driver_register(&onboard_hub_driver);
+	ret = usb_register_device_driver(&onboard_hub_usbdev_driver, THIS_MODULE);
 	if (ret)
 		return ret;
 
-	ret = usb_register_device_driver(&onboard_hub_usbdev_driver, THIS_MODULE);
+	ret = platform_driver_register(&onboard_hub_driver);
 	if (ret)
-		platform_driver_unregister(&onboard_hub_driver);
+		usb_deregister_device_driver(&onboard_hub_usbdev_driver);
 
 	return ret;
 }
-- 
2.39.0.314.g84b9a713c41-goog