On Thu, 5 Dec 2013, Julius Werner wrote:
> usb_deauthorize_device() tries to unset the configuration of a USB
> device and then unconditionally blows away the configuration descriptors
> with usb_destroy_configuration(). This is bad if the
> usb_set_configuration() call failed before the configuration could be
> correctly unset, since pointers like udev->actconfig can keep pointing
> to the now invalid memory. We have encountered hard to reproduce crashes
> from devices disconnected during suspend due to this, where khubd's
> disconnect handling races with userspace tools that change authorization
> on resume.
>
> It seems desirable that a USB device can always be marked as
> unconfigured (reclaiming its bandwidth) in the kernel, regardless of
> communication problems. This patch changes usb_set_configuration() to
> ignore all failures in the case where no new configuration is being set.
>
> Signed-off-by: Julius Werner <jwer...@chromium.org>
Sorry for not getting back to this sooner. Ironically, it looks like
this change isn't needed any more, thanks to Thomas Pugliese's patch:
http://marc.info/?l=linux-usb&m=138661805209999&w=2
> --- a/drivers/usb/core/message.c
> +++ b/drivers/usb/core/message.c
> @@ -1774,7 +1775,7 @@ free_interfaces:
>
> /* Wake up the device so we can send it the Set-Config request */
> ret = usb_autoresume_device(dev);
> - if (ret)
> + if (ret && cp)
> goto free_interfaces;
That isn't quite right. If the autoresume fails then we have to skip
the autosuspend call later on.
Alan Stern
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