RE: [PATCH] usb: gadget: udc-core: call udc_stop() before gadget unbind

[Krzysztof Opasiak]

> -----Original Message-----
> From: Robert Baldyga [mailto:r.baldyga@xxxxxxxxxxx]
> Sent: Friday, December 12, 2014 2:17 PM
> To: balbi@xxxxxx
> Cc: gregkh@xxxxxxxxxxxxxxxxxxx; peter.chen@xxxxxxxxxxxxx; linux-
> usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> m.szyprowski@xxxxxxxxxxx; k.opasiak@xxxxxxxxxxx; Robert Baldyga
> Subject: [PATCH] usb: gadget: udc-core: call udc_stop() before
> gadget unbind
> 
> As usb function drivers assumes that all usb request will be
> completed
> before function unbind call, we should supply such behavior. In
> some
> cases ep_disable() won't kill all request effectively, because some
> IN requests can be in running state. In such situation it's
> possible
> to have unbind function called before last request completion,
> which
> can cause problems.
> 
> For example unbinding f_ecm function while request on 'notify'
> endpoint
> is not completed, ends up NULL pointer dereference in unbind()
> function.
> 
> usb_gadget_udc_stop() call causes completion of all requests so if
> it's
> called before gadget unbind there is no risk that some of requests
> will
> stay uncompleted.
> 
> Signed-off-by: Robert Baldyga <r.baldyga@xxxxxxxxxxx>

This finally solves issue described before in [1]

Tested-by: Krzysztof Opasiak <k.opasiak@xxxxxxxxxxx>

Footnotes:
1 - https://lkml.org/lkml/2014/12/9/283

-- 
Krzysztof Opasiak
Samsung R&D Institute Poland
Samsung Electronics
k.opasiak@xxxxxxxxxxx




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