On Wed, Sep 02, 2020 at 01:01:03PM +0200, Greg Kroah-Hartman wrote:
> snd_usb_pipe_sanity_check() is a great function, so let's move it into
> the USB core so that other parts of the kernel, including the USB core,
> can call it.
> 
> Name it usb_pipe_type_check() to match the existing
> usb_urb_ep_type_check() call, which now uses this function.
> 
> Cc: Jaroslav Kysela <[email protected]>
> Cc: Takashi Iwai <[email protected]>
> Cc: "Gustavo A. R. Silva" <[email protected]>
> Cc: Eli Billauer <[email protected]>
> Cc: Emiliano Ingrassia <[email protected]>
> Cc: Alan Stern <[email protected]>
> Cc: Alexander Tsoy <[email protected]>
> Cc: "Geoffrey D. Bennett" <[email protected]>
> Cc: Jussi Laako <[email protected]>
> Cc: Nick Kossifidis <[email protected]>
> Cc: Dmitry Panchenko <[email protected]>
> Cc: Chris Wulff <[email protected]>
> Cc: Jesus Ramos <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Greg Kroah-Hartman <[email protected]>
> ---

> diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
> index 27e83e55a590..45bc2914c1ba 100644
> --- a/drivers/usb/core/urb.c
> +++ b/drivers/usb/core/urb.c
> @@ -192,24 +192,39 @@ static const int pipetypes[4] = {
>  };
>  
>  /**
> - * usb_urb_ep_type_check - sanity check of endpoint in the given urb
> - * @urb: urb to be checked
> + * usb_pipe_type_check - sanity check of a specific pipe for a usb device
> + * @dev: struct usb_device to be checked
> + * @pipe: pipe to check
>   *
>   * 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.
> + * given usb device.  It returns 0 if the pipe is a valid for the specific 
> usb
-----------------------------------------------------^
Typo.

> + * device, otherwise a negative error code.
>   */
> -int usb_urb_ep_type_check(const struct urb *urb)
> +int usb_pipe_type_check(struct usb_device *dev, unsigned int pipe)
>  {
>       const struct usb_host_endpoint *ep;
>  
> -     ep = usb_pipe_endpoint(urb->dev, urb->pipe);
> +     ep = usb_pipe_endpoint(dev, pipe);
>       if (!ep)
>               return -EINVAL;
> -     if (usb_pipetype(urb->pipe) != pipetypes[usb_endpoint_type(&ep->desc)])
> +     if (usb_pipetype(pipe) != pipetypes[usb_endpoint_type(&ep->desc)])
>               return -EINVAL;
>       return 0;
>  }
> +EXPORT_SYMBOL_GPL(usb_pipe_type_check);
> +
> +/**
> + * usb_urb_ep_type_check - 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_type_check(const struct urb *urb)
> +{
> +     return usb_pipe_type_check(urb->dev, urb->pipe);
> +}
>  EXPORT_SYMBOL_GPL(usb_urb_ep_type_check);

Since this routine is used in only one place in the entire kernel, you 
might as well inline the code there and get rid of the function 
entirely.

> diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
> index abf99b814a0f..fc3aab04a0bc 100644
> --- a/sound/usb/quirks.c
> +++ b/sound/usb/quirks.c
> @@ -846,7 +846,7 @@ static int snd_usb_accessmusic_boot_quirk(struct 
> usb_device *dev)
>       static const u8 seq[] = { 0x4e, 0x73, 0x52, 0x01 };
>       void *buf;
>  
> -     if (snd_usb_pipe_sanity_check(dev, usb_sndintpipe(dev, 0x05)))
> +     if (usb_pipe_type_check(dev, usb_sndintpipe(dev, 0x05)))
>               return -EINVAL;
>       buf = kmemdup(seq, ARRAY_SIZE(seq), GFP_KERNEL);
>       if (!buf)
> @@ -875,7 +875,7 @@ static int snd_usb_nativeinstruments_boot_quirk(struct 
> usb_device *dev)
>  {
>       int ret;
>  
> -     if (snd_usb_pipe_sanity_check(dev, usb_sndctrlpipe(dev, 0)))
> +     if (usb_pipe_type_check(dev, usb_sndctrlpipe(dev, 0)))
>               return -EINVAL;

In a few places here this check is completely unnecessary.  All it does 
is verify that the device does have an endpoint 0 and the the type of 
the endpoint matches the type of the pipe.  Well, every USB device 
always has an endpoint 0, and it is always a bidirectional control 
endpoint.  Therefore a simple static check is all you need: There's no 
point calling usb_pipe_type_check() when the pipe is of the form 
usb_{snd|rcv}ctrlpipe(dev, 0).

In short, this check should be removed completely; it does nothing.

>       ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
>                                 0xaf, USB_TYPE_VENDOR | USB_RECIP_DEVICE,
> @@ -984,7 +984,7 @@ static int snd_usb_axefx3_boot_quirk(struct usb_device 
> *dev)
>  
>       dev_dbg(&dev->dev, "Waiting for Axe-Fx III to boot up...\n");
>  
> -     if (snd_usb_pipe_sanity_check(dev, usb_sndctrlpipe(dev, 0)))
> +     if (usb_pipe_type_check(dev, usb_sndctrlpipe(dev, 0)))

Same for this check.

>               return -EINVAL;
>       /* If the Axe-Fx III has not fully booted, it will timeout when trying
>        * to enable the audio streaming interface. A more generous timeout is
> @@ -1018,7 +1018,7 @@ static int snd_usb_motu_microbookii_communicate(struct 
> usb_device *dev, u8 *buf,
>  {
>       int err, actual_length;
>  
> -     if (snd_usb_pipe_sanity_check(dev, usb_sndintpipe(dev, 0x01)))
> +     if (usb_pipe_type_check(dev, usb_sndintpipe(dev, 0x01)))
>               return -EINVAL;
>       err = usb_interrupt_msg(dev, usb_sndintpipe(dev, 0x01), buf, *length,
>                               &actual_length, 1000);
> @@ -1030,7 +1030,7 @@ static int snd_usb_motu_microbookii_communicate(struct 
> usb_device *dev, u8 *buf,
>  
>       memset(buf, 0, buf_size);
>  
> -     if (snd_usb_pipe_sanity_check(dev, usb_rcvintpipe(dev, 0x82)))
> +     if (usb_pipe_type_check(dev, usb_rcvintpipe(dev, 0x82)))
>               return -EINVAL;
>       err = usb_interrupt_msg(dev, usb_rcvintpipe(dev, 0x82), buf, buf_size,
>                               &actual_length, 1000);
> @@ -1117,7 +1117,7 @@ static int snd_usb_motu_m_series_boot_quirk(struct 
> usb_device *dev)
>  {
>       int ret;
>  
> -     if (snd_usb_pipe_sanity_check(dev, usb_sndctrlpipe(dev, 0)))
> +     if (usb_pipe_type_check(dev, usb_sndctrlpipe(dev, 0)))

And this one.

>               return -EINVAL;
>       ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
>                             1, USB_TYPE_VENDOR | USB_RECIP_DEVICE,

Alan Stern

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