usb: core: Add a helper function to check the validity of EP type in URB

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.

Tested-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 28 insertions, 4 deletions

diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 47903d510955..8b800e34407b 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_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)
+{
+        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_type_check);
+
 /**
  * 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;
@@ -444,7 +466,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
          */
 
         /* Check that the pipe's type matches the endpoint's type */
-        if (usb_pipetype(urb->pipe) != pipetypes[xfertype])
+        if (usb_urb_ep_type_check(urb))
                 dev_WARN(&dev->dev, "BOGUS urb xfer, pipe %x != type %x\n",
                         usb_pipetype(urb->pipe), pipetypes[xfertype]);
 
diff --git a/include/linux/usb.h b/include/linux/usb.h
index cb9fbd54386e..2b861804fffa 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1728,6 +1728,8 @@ static inline int usb_urb_dir_out(struct urb *urb)
         return (urb->transfer_flags & URB_DIR_MASK) == URB_DIR_OUT;
 }
 
+int usb_urb_ep_type_check(const struct urb *urb);
+
 void *usb_alloc_coherent(struct usb_device *dev, size_t size,
         gfp_t mem_flags, dma_addr_t *dma);
 void usb_free_coherent(struct usb_device *dev, size_t size,