Re: [PATCH] usb: hcd: get/put device and hcd for hcd_buffers()

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

* Alan Stern | 2014-12-05 16:21:02 [-0500]:

>On Fri, 5 Dec 2014, Sebastian Andrzej Siewior wrote:
>> So instead, I hold the device struct in the HCD and the HCD struct on
>> every USB-buf-alloc. That means after a disconnect we still have a
>> refcount on usb_hcd and device and it will be cleaned "later" once the
>> last USB-buffer is released.
>
>This is not a valid solution.  Notice that your _hcd_buffer_free still 
>dereferences hcd->driver; that will not point to anything useful if you 
>rmmod the HCD.
Hmm. You're right, that one is gone.

>Also, you neglected to move the calls to hcd_buffer_destroy from 
>usb_remove_hcd to hcd_release.
I add them, I didn't move them.

>On the whole, it would be easier if the UVC driver could release its 
>coherent DMA buffers during the disconnect callback.  If that's not 
>feasible we'll have to find some other solution.

I had one patch doing that. Let me grab it out on Monday.

>Alan Stern
>
Sebastian