usb: gadget: define free_ep_req as universal function

This function is shared between gadget functions, so this avoid unnecessary
duplicated code and potentially avoid memory leaks.

Reviewed-by: Robert Baldyga <[e-mail]>
Signed-off-by: Felipe F. Tonello <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/gadget/function/f_midi.c

···
 	return alloc_ep_req(ep, length, length);
 }
 
-static void free_ep_req(struct usb_ep *ep, struct usb_request *req)
-{
-	kfree(req->buf);
-	usb_ep_free_request(ep, req);
-}
-
 static const uint8_t f_midi_cin_length[] = {
 	0, 0, 2, 3, 3, 1, 2, 3, 3, 3, 3, 3, 2, 2, 3, 1
 };

drivers/usb/gadget/function/f_sourcesink.c

···
 	return alloc_ep_req(ep, len, ss->buflen);
 }
 
-void free_ep_req(struct usb_ep *ep, struct usb_request *req)
-{
-	kfree(req->buf);
-	usb_ep_free_request(ep, req);
-}
-
 static void disable_ep(struct usb_composite_dev *cdev, struct usb_ep *ep)
 {
 	int			value;

drivers/usb/gadget/function/g_zero.h

···
 int lb_modinit(void);
 
 /* common utilities */
-void free_ep_req(struct usb_ep *ep, struct usb_request *req);
 void disable_endpoints(struct usb_composite_dev *cdev,
 		struct usb_ep *in, struct usb_ep *out,
 		struct usb_ep *iso_in, struct usb_ep *iso_out);

drivers/usb/gadget/u_f.c

···
  * published by the Free Software Foundation.
  */
 
-#include <linux/usb/gadget.h>
 #include "u_f.h"
 
 struct usb_request *alloc_ep_req(struct usb_ep *ep, int len, int default_len)

drivers/usb/gadget/u_f.h

···
 #ifndef __U_F_H__
 #define __U_F_H__
 
+#include <linux/usb/gadget.h>
+
 /* Variable Length Array Macros **********************************************/
 #define vla_group(groupname) size_t groupname##__next = 0
 #define vla_group_size(groupname) groupname##__next
···
 struct usb_ep;
 struct usb_request;
 
+/* Requests allocated via alloc_ep_req() must be freed by free_ep_req(). */
 struct usb_request *alloc_ep_req(struct usb_ep *ep, int len, int default_len);
+static inline void free_ep_req(struct usb_ep *ep, struct usb_request *req)
+{
+	kfree(req->buf);
+	usb_ep_free_request(ep, req);
+}
 
 #endif /* __U_F_H__ */
-
-