On Tue, Sep 6, 2011 at 6:31 AM, Sitsofe Wheeler <sitsofe@xxxxxxxxx> wrote: > On Mon, Sep 05, 2011 at 12:16:42PM +0200, Hans Verkuil wrote: >> On Monday, September 05, 2011 12:13:26 Hans Verkuil wrote: >> > >> > The original order is correct, but what I missed is that for drivers >> > that release (free) everything in the videodev release callback the >> > v4l2_device struct is also freed and v4l2_device_put will fail. >> > >> > To fix this, add this code just before the vdev->release call: >> > >> > /* Do not call v4l2_device_put if there is no release callback set. */ >> > if (v4l2_dev->release == NULL) >> > v4l2_dev = NULL; >> > >> > If there is no release callback, then the refcounting is pointless >> > anyway. >> > >> > This should work. >> >> Note that in the long run using the v4l2_device release callback >> instead of the videodev release is better. But it's a lot of work to >> convert everything so that's long term. I'm quite surprised BTW that >> this bug wasn't found much earlier. > > This inline patch fixes the second "poison overwritten" problem so: > Tested-by: Sitsofe Wheeler <sitsofe@xxxxxxxxx> Confirmed > > However, it does not prevent the original oops that was reported in the > original message. Yang Ruirui's patch in > https://lkml.org/lkml/2011/9/1/74 seems to be required to resolve > that initial problem - can it be ACK'd? Yang's patch is reproduced > inline below: Thanks, If it's ok, I can resend it as inline. > > For uvc device, dev->vdev.dev is the &intf->dev, > uvc_delete code is as below: > usb_put_intf(dev->intf); > usb_put_dev(dev->udev); > > uvc_status_cleanup(dev); > uvc_ctrl_cleanup_device(dev); > > ## the intf dev is released above, so below code will oops. > > if (dev->vdev.dev) > v4l2_device_unregister(&dev->vdev); > Fix it by get_device in v4l2_device_register and put_device in v4l2_device_disconnect > --- > drivers/media/video/v4l2-device.c | 2 ++ > 1 file changed, 2 insertions(+) > diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c > index c72856c..e6a2c3b 100644 > --- a/drivers/media/video/v4l2-device.c > +++ b/drivers/media/video/v4l2-device.c > @@ -38,6 +38,7 @@ int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev) > mutex_init(&v4l2_dev->ioctl_lock); > v4l2_prio_init(&v4l2_dev->prio); > kref_init(&v4l2_dev->ref); > + get_device(dev); > v4l2_dev->dev = dev; > if (dev == NULL) { > /* If dev == NULL, then name must be filled in by the caller */ > @@ -93,6 +94,7 @@ void v4l2_device_disconnect(struct v4l2_device *v4l2_dev) > > if (dev_get_drvdata(v4l2_dev->dev) == v4l2_dev) > dev_set_drvdata(v4l2_dev->dev, NULL); > + put_device(v4l2_dev->dev); > v4l2_dev->dev = NULL; > } > EXPORT_SYMBOL_GPL(v4l2_device_disconnect); > > -- > Sitsofe | http://sucs.org/~sits/ > -- Regards Yang RuiRui -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
