From a116a05cb4c2d057b3e15ef3bd0f3d657cb6ef99 Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Sat, 7 Jan 2012 09:52:38 -0300 Subject: [PATCH] [media] cx231xx: fix crash after load/unload/load of module The following sequence of commands was triggering a kernel crash in cdev_get(): modprobe cx231xx rmmod cx231xx modprobe cx231xx v4l2grab -n 1 The problem was that cx231xx_usb_disconnect() was not doing anything because the test: if (!dev->udev) return; was reached (i.e, dev->udev was NULL). This is due to the fact that the 'dev' pointer placed as intfdata into the usb_interface structure had the wrong value, because cx231xx_probe() was doing the usb_set_intfdata() on the wrong usb_interface structure. For some reason, cx231xx_probe() was doing the following: static int cx231xx_usb_probe(struct usb_interface *interface, const struct usb_device_id *id) { struct usb_interface *lif = NULL; [...] /* store the current interface */ lif = interface; [...] /* store the interface 0 back */ lif = udev->actconfig->interface[0]; [...] usb_set_intfdata(lif, dev); [...] retval = v4l2_device_register(&interface->dev, &dev->v4l2_dev); [...] } So, the usb_set_intfdata() was done on udev->actconfig->interface[0] and not on the 'interface' passed as argument to the ->probe() and ->disconnect() hooks. Later on, v4l2_device_register() was initializing the intfdata of the correct usb_interface structure as a pointer to the v4l2_device structure. Upon unregistration, the ->disconnect() hook was getting the intfdata of the usb_interface passed as argument... and casted it to a 'struct cx231xx *' while it was in fact a 'struct v4l2_device *'. The correct fix seems to just be to set the intfdata on the proper interface from the beginning. Now, loading/unloading/reloading the driver allows to use the device properly. Signed-off-by: Thomas Petazzoni Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/cx231xx/cx231xx-cards.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/media/video/cx231xx/cx231xx-cards.c b/drivers/media/video/cx231xx/cx231xx-cards.c index 53dae2a..bfcc8ab 100644 --- a/drivers/media/video/cx231xx/cx231xx-cards.c +++ b/drivers/media/video/cx231xx/cx231xx-cards.c @@ -1135,7 +1135,7 @@ static int cx231xx_usb_probe(struct usb_interface *interface, cx231xx_info("registering interface %d\n", ifnum); /* save our data pointer in this interface device */ - usb_set_intfdata(lif, dev); + usb_set_intfdata(interface, dev); /* * AV device initialization - only done at the last interface @@ -1157,7 +1157,7 @@ static int cx231xx_usb_probe(struct usb_interface *interface, v4l2_device_unregister(&dev->v4l2_dev); kfree(dev); dev = NULL; - usb_set_intfdata(lif, NULL); + usb_set_intfdata(interface, NULL); return retval; } -- 2.7.4