[linux-dvb] Re: [Patch] USBVision - Fix NT1005 Bridge detection

Thierry MERLE thierry.merle at free.fr
Sat Apr 14 23:00:13 CEST 2007




Mauro Carvalho Chehab a écrit :
> Hi Thierry,
>
>   
>> I am currently debugging the Trent's patch that makes a kernel oops and 
>> I don't know why.
>> The usbvision_probe is called event if the device is not plugged, and 
>> the kernel oops occurs on this piece of code:
>>     model = devid->driver_info;
>>     printk(KERN_INFO "%s: %s found\n", __FUNCTION__,
>>                 usbvision_device_data[model].ModelString);
>>
>> Memory alignment problem ? Why this probe is called even if there is no 
>> device plugged-in ?
>>     
> Very weird. It shouldn't be called when no device is plugged...
>
>   
>> By putting something like:
>>     model = devid->driver_info;
>>     if(model<0 || model >HPG_WINTV) {
>>         printk(KERN_INFO "model out of bounds %d\n",model);
>>         return -ENODEV;
>>     } else printk(KERN_INFO "model is %d\n",model);
>>
>> The problem disappeared...
>>     
>
> A similar code is also present on em28xx. Anyway, it is better to have
> this kind of protection. I've added a patch, based on yours, fixing the
> bug. As you'd agreed, I've pushed the patches to master tree.
>
> It is better, however, to check why it is calling the code, without a
> valid USB ID, since it may mean a future trouble...
>
>   
If I delete this line in the device_table:
{ USB_DEVICE(0xfff0, 0xfff0), .driver_info=DUMMY_DEVICE },
there is no more call to the usb probe function. But I think I will lose 
the custom device facility.
I think these USB_DEVICE parameters are special ones indicating to usb 
core that usbvision_probe must be called for unclaimed devices.
I plugged a new USB peripheral without having plugged the corresponding 
driver, I got the "model out of bounds" message. printk should be 
changed to a PDEBUG in order to deactivate this log by default (did it 
in my repository).
> Btw, I think we can also apply this one also:
>
> diff -r 6b6805e3c76d linux/drivers/media/video/usbvision/usbvision-video.c
> --- a/linux/drivers/media/video/usbvision/usbvision-video.c	Sat Apr 14 15:17:08 2007 -0300
> +++ b/linux/drivers/media/video/usbvision/usbvision-video.c	Sat Apr 14 15:19:06 2007 -0300
> @@ -1985,8 +1985,6 @@ static int __devinit usbvision_probe(str
>  		return -ENODEV;
>  	}
>  
> -	usb_get_dev(dev);
> -
>  	if ((usbvision = usbvision_alloc(dev)) == NULL) {
>  		err("%s: couldn't allocate USBVision struct", __FUNCTION__);
>  		return -ENOMEM;
>
>
> usb_get_dev() is already called previously on usbvision_probe.
>
>   




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