On Sat, Dec 06, 2014 at 12:13:13AM +0100, Sebastian Andrzej Siewior wrote: > * Greg Kroah-Hartman | 2014-12-05 13:19:32 [-0800]: > > >On Fri, Dec 05, 2014 at 09:03:57PM +0100, Sebastian Andrzej Siewior wrote: > >> Consider the following scenario: > >> - plugin a webcam > >> - play the stream via gst-launch-0.10 v4l2src device=/dev/video0… > >> - remove the USB-HCD during playback via "rmmod $HCD" > >> > >> and now wait for the crash > > > >Which you deserve, why did you ever remove a kernel module? That's racy > its been found by the testing team and looks legitimate. > > >and _never_ recommended, which is why it never happens automatically and > >only root can do it. > I beg your pardon. So it is okay to remove the UVC-driver / plug the > cable and expect that things continue to work but removing the HCD is a > no no? If you hot unplug the HCD and this is an issue, yes, that's something to fix. If you can only trigger this by unloading a kernel module, no, it's not a big issue at all. It's pretty trivial to cause kernel oopses by unloading kernel modules if you know what you are doing. > >> diff --git a/drivers/usb/core/buffer.c b/drivers/usb/core/buffer.c > >> index 506b969ea7fd..01e080a61519 100644 > >> --- a/drivers/usb/core/buffer.c > >> +++ b/drivers/usb/core/buffer.c > >> @@ -107,7 +107,7 @@ void hcd_buffer_destroy(struct usb_hcd *hcd) > >> * better sharing and to leverage mm/slab.c intelligence. > >> */ > >> > >> -void *hcd_buffer_alloc( > >> +static void *_hcd_buffer_alloc( > > > >Looks like this isn't really needed here, right? > > either this or I would have the tree callers if the allocation succeded > or not in order not to take a reference if the allocation failed. My point is this isn't needed for this patch. greg k-h -- 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
