linux-kernel - Re: [PATCH v2 1/2] usb: gadget: udc: core: Revise comments for usb_ep

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Message-ID: <20211027142422.GA1319606@rowland.harvard.edu>
Date:   Wed, 27 Oct 2021 10:24:22 -0400
From:   Alan Stern <stern@...land.harvard.edu>
To:     Wesley Cheng <quic_wcheng@...cinc.com>
Cc:     balbi@...nel.org, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        jackp@...eaurora.org
Subject: Re: [PATCH v2 1/2] usb: gadget: udc: core: Revise comments for
 usb_ep_disable()

On Tue, Oct 26, 2021 at 07:50:24PM -0700, Wesley Cheng wrote:
> The usb_ep_disable() routine is being widely used directly in the
> disconnect callback path by function drivers.  Hence, the statement
> about it being able to only run in process context may not be true.
> 
> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
> ---
>  drivers/usb/gadget/udc/core.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index d626511..e1f90d8 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -136,8 +136,6 @@ EXPORT_SYMBOL_GPL(usb_ep_enable);
>   * gadget drivers must call usb_ep_enable() again before queueing
>   * requests to the endpoint.
>   *
> - * This routine must be called in process context.
> - *
>   * returns zero, or a negative error code.
>   */
>  int usb_ep_disable(struct usb_ep *ep)

You should also change the kerneldoc for usb_ep_enable.  Neither routine 
needs to be called in process context.

In fact, it might be good to change both comments to:

 * This routine may be called in an atomic (interrupt) context.

just to be totally explicit.

Alan Stern