linux-kernel - Re: [PATCH v1 2/2] usb: gadget: udc: core: Prevent redundant calls to pullup

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Date:   Wed, 5 Apr 2023 19:15:55 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Badhri Jagan Sridharan <badhri@...gle.com>
Cc:     stern@...land.harvard.edu, colin.i.king@...il.com,
        xuetao09@...wei.com, quic_eserrao@...cinc.com,
        water.zhangjiantao@...wei.com, peter.chen@...escale.com,
        balbi@...com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v1 2/2] usb: gadget: udc: core: Prevent redundant calls
 to pullup

On Wed, Apr 05, 2023 at 09:31:33AM +0000, Badhri Jagan Sridharan wrote:
> usb_gadget_connect calls gadget->ops->pullup without
> checking whether gadget->connected was previously set.
> Make this symmetric to usb_gadget_disconnect by returning
> early if gadget->connected is already set.
> 
> Cc: stable@...r.kernel.org
> 
> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
> Fixes: 5a1da544e572 ("usb: gadget: core: do not try to disconnect gadget if it is not connected")

Same changelog comment as before.

> ---
>  drivers/usb/gadget/udc/core.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 890f92cb6344..7eeaf7dbb350 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -708,6 +708,9 @@ int usb_gadget_connect(struct usb_gadget *gadget)
>  		goto out;
>  	}
>  
> +	if (gadget->connected)
> +		goto out;
> +

What prevents this connected value from changing right after you check
this?

thanks,

greg k-h