linux-kernel - Re: [PATCH] usb: gadget: udc: core: Fix error case while binding pending gadget drivers

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Message-ID: <Pine.LNX.4.44L0.1908211027430.1816-100000@iolanthe.rowland.org>
Date:   Wed, 21 Aug 2019 10:30:10 -0400 (EDT)
From:   Alan Stern <stern@...land.harvard.edu>
To:     Roger Quadros <rogerq@...com>
cc:     balbi@...nel.org, <gregkh@...uxfoundation.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: gadget: udc: core: Fix error case while binding
 pending gadget drivers

On Wed, 21 Aug 2019, Roger Quadros wrote:

> If binding a pending gadget driver fails we should not
> remove it from the pending driver list, otherwise it
> will cause a segmentation fault later when the gadget driver is
> unloaded.

> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
>  drivers/usb/gadget/udc/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 7cf34beb50df..c272c8014772 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -1142,7 +1142,7 @@ static int check_pending_gadget_drivers(struct usb_udc *udc)
>  		if (!driver->udc_name || strcmp(driver->udc_name,
>  						dev_name(&udc->dev)) == 0) {
>  			ret = udc_bind_to_driver(udc, driver);
> -			if (ret != -EPROBE_DEFER)
> +			if (!ret)
>  				list_del(&driver->pending);
>  			break;
>  		}

This is kind of a policy question.  If binding a pending gadget driver 
fails, should the driver remain pending?

Depending on the answer to this question, you might want to change the 
list_del to list_del_init.  That should fix the segmentation fault 
just as well.

Alan Stern