[alsa-devel] [PATCH 1/9] usb: core: Add a helper function to check the validity of EP type in URB

[Takashi Iwai]

On Tue, 10 Oct 2017 15:53:49 +0200,
Greg KH wrote:
> 
> On Tue, Oct 10, 2017 at 03:38:11PM +0200, Takashi Iwai wrote:
> > This patch adds a new helper function to perform a sanity check of the
> > given URB to see whether it contains a valid endpoint.  It's a light-
> > weight version of what usb_submit_urb() does, but without the kernel
> > warning followed by the stack trace, just returns an error code.
> > 
> > Especially for a driver that doesn't parse the descriptor but fills
> > the URB with the fixed endpoint (e.g. some quirks for non-compliant
> > devices), this kind of check is preferable at the probe phase before
> > actually submitting the urb.
> > 
> > Signed-off-by: Takashi Iwai <tiwai at suse.de>
> > ---
> >  drivers/usb/core/urb.c | 28 +++++++++++++++++++++++++---
> >  include/linux/usb.h    |  2 ++
> >  2 files changed, 27 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
> > index 47903d510955..580dfaec8af7 100644
> > --- a/drivers/usb/core/urb.c
> > +++ b/drivers/usb/core/urb.c
> > @@ -187,6 +187,31 @@ EXPORT_SYMBOL_GPL(usb_unanchor_urb);
> >  
> >  /*-------------------------------------------------------------------*/
> >  
> > +static const int pipetypes[4] = {
> > +	PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
> > +};
> > +
> > +/**
> > + * usb_urb_ep_check_type - sanity check of endpoint in the given urb
> > + * @urb: urb to be checked
> > + *
> > + * This performs a light-weight sanity check for the endpoint in the
> > + * given urb.  It returns 0 if the urb contains a valid endpoint, otherwise
> > + * a negative error code.
> > + */
> > +int usb_urb_ep_check_type(const struct urb *urb)
> > +{
> > +	const struct usb_host_endpoint *ep;
> > +
> > +	ep = usb_pipe_endpoint(urb->dev, urb->pipe);
> > +	if (!ep)
> > +		return -EINVAL;
> > +	if (usb_pipetype(urb->pipe) != pipetypes[usb_endpoint_type(&ep->desc)])
> > +		return -EINVAL;
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(usb_urb_ep_check_type);
> > +
> >  /**
> >   * usb_submit_urb - issue an asynchronous transfer request for an endpoint
> >   * @urb: pointer to the urb describing the request
> > @@ -326,9 +351,6 @@ EXPORT_SYMBOL_GPL(usb_unanchor_urb);
> >   */
> >  int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
> >  {
> > -	static int			pipetypes[4] = {
> > -		PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
> > -	};
> >  	int				xfertype, max;
> >  	struct usb_device		*dev;
> >  	struct usb_host_endpoint	*ep;
> 
> Can you also call usb_urb_ep_check_type() in usb_submit_urb()?

OK, will do that in v2 patch.


thanks,

Takashi