linux-kernel - Re: [PATCH] usb: gadget: gadgetfs: unregister gadget only if it got successfully registered

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Date:	Mon, 8 Feb 2016 13:33:15 +0100
From:	Vegard Nossum <vegard.nossum@...cle.com>
To:	Marek Szyprowski <m.szyprowski@...sung.com>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Ruslan Bilovol <ruslan.bilovol@...il.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Peter Chen <peter.chen@...escale.com>,
	Felipe Balbi <balbi@...nel.org>
Subject: Re: [PATCH] usb: gadget: gadgetfs: unregister gadget only if it got
 successfully registered

On 02/08/2016 01:15 PM, Marek Szyprowski wrote:
> Gadgetfs driver called usb_gadget_unregister_driver unconditionally, even
> if it didn't register it earlier due to other failures. This patch fixes
> this.
>
> Reported-by: Vegard Nossum <vegard.nossum@...cle.com>
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
>   drivers/usb/gadget/legacy/inode.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
> index 7a62a2f7bc18..cde6a2133c90 100644
> --- a/drivers/usb/gadget/legacy/inode.c
> +++ b/drivers/usb/gadget/legacy/inode.c
> @@ -130,7 +130,8 @@ struct dev_data {
>   					setup_can_stall : 1,
>   					setup_out_ready : 1,
>   					setup_out_error : 1,
> -					setup_abort : 1;
> +					setup_abort : 1,
> +					gadget_registered : 1;
>   	unsigned			setup_wLength;
>
>   	/* the rest is basically write-once */
> @@ -1179,7 +1180,8 @@ dev_release (struct inode *inode, struct file *fd)
>
>   	/* closing ep0 === shutdown all */
>
> -	usb_gadget_unregister_driver (&gadgetfs_driver);
> +	if (dev->gadget_registered)
> +		usb_gadget_unregister_driver (&gadgetfs_driver);
>
>   	/* at this point "good" hardware has disconnected the
>   	 * device from USB; the host won't see it any more.
> @@ -1825,6 +1827,7 @@ dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
>   		 * kick in after the ep0 descriptor is closed.
>   		 */
>   		value = len;
> +		dev->gadget_registered = true;
>   	}
>   	return value;
>
>

That (along with the first patch) fixes the problem! Thanks.

It also seems to have fixed another crash I was seeing with
req->complete == NULL in usb_gadget_giveback_request().


Vegard