linux-kernel - Re: Kernel Oops while disconnecting USB peripheral (always)

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Date:	Sat, 28 Jul 2012 12:19:16 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Daniel Mack <zonque@...il.com>
cc:	Bjørn Mork <bjorn@...k.no>,
	Sarbojit Ganguly <unixman.linuxboy@...il.com>,
	<gregkh@...uxfoundation.org>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Takashi Iwai <tiwai@...e.de>
Subject: Re: Kernel Oops while disconnecting USB peripheral (always)

On Sat, 28 Jul 2012, Daniel Mack wrote:

> Hmm, interesting. Thanks for sharing this. I personally never saw this
> bug kicking in, but if I understand your findings correctly, we would
> need something like the following patch for snd-usb and the storage driver?
> 
> Sarbojit, could you give this a test and see whether your kernel still
> crashes in any of the two drivers?


> --- a/drivers/usb/storage/usb.c
> +++ b/drivers/usb/storage/usb.c
> @@ -1025,9 +1025,14 @@ void usb_stor_disconnect(struct usb_interface *intf)
>  {
>         struct us_data *us = usb_get_intfdata(intf);
> 
> +       if (!us)
> +               return;

This can never happen.  The disconnect routine gets called only once, 
so us will not be NULL.

> +
>         US_DEBUGP("storage_disconnect() called\n");
>         quiesce_and_remove_host(us);
>         release_everything(us);
> +
> +       usb_set_intfdata(intf, NULL);
>  }
>  EXPORT_SYMBOL_GPL(usb_stor_disconnect);

Alan Stern

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