[PATCH 1/2] usb:gadget:composite: add public functions for managing setup requests

[Enrico Scholz <enrico.scholz@sigma-chemnitz.de>]

From: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>

The composite driver does some bookkeeping about pending requests and
decides in its cleanup function whether requests must be dequeued.

There are some function drivers (dfu, acm) which queue the requests
directly which causes e.g.

| :/ dfu /tmp/img(img)c
| ...
| g_multi gadget0: high-speed config #1: Multifunction Composite Gadget
| fsl_free_request: Freeing queued request
| [<2fd8d8e5>] (unwind_backtrace+0x1/0x78) from [<2fd34b1f>] (fsl_free_request+0x1f/0x34)
| [<2fd34b1f>] (fsl_free_request+0x1f/0x34) from [<2fd337cf>] (composite_dev_cleanup+0x77/0xc0)
| [<2fd337cf>] (composite_dev_cleanup+0x77/0xc0) from [<2fd33867>] (__composite_unbind+0x4f/0x94)
| [<2fd33867>] (__composite_unbind+0x4f/0x94) from [<2fd3432b>] (gadget_unbind_driver+0x37/0x70)
| [<2fd3432b>] (gadget_unbind_driver+0x37/0x70) from [<2fd1275f>] (device_remove+0xf/0x20)
| [<2fd1275f>] (device_remove+0xf/0x20) from [<2fd1289b>] (unregister_driver+0x47/0x60)
| [<2fd1289b>] (unregister_driver+0x47/0x60) from [<2fd34663>] (usb_gadget_unregister_driver+0xf/0x18)
| [<2fd34663>] (usb_gadget_unregister_driver+0xf/0x18) from [<2fd37c5b>] (usb_multi_unregister+0x13/0x30)
| [<2fd37c5b>] (usb_multi_unregister+0x13/0x30) from [<2fd59f67>] (do_dfu+0x47/0x68)
| [<2fd59f67>] (do_dfu+0x47/0x68) from [<2fd04fdf>] (execute_command+0x23/0x4c)
| [<2fd04fdf>] (execute_command+0x23/0x4c) from [<2fd0a737>] (run_list_real+0x5ef/0x690)
| [<2fd0a737>] (run_list_real+0x5ef/0x690) from [<2fd0a00b>] (parse_stream_outer+0xc7/0x154)
| [<2fd0a00b>] (parse_stream_outer+0xc7/0x154) from [<2fd0a927>] (run_shell+0x3f/0x6c)
| [<2fd0a927>] (run_shell+0x3f/0x6c) from [<2fd01103>] (run_init+0xeb/0x210)
| [<2fd01103>] (run_init+0xeb/0x210) from [<2fd01253>] (start_barebox+0x2b/0x6c)
| [<2fd01253>] (start_barebox+0x2b/0x6c) from [<2fd89b37>] (barebox_non_pbl_start+0xc3/0x108)
| [<2fd89b37>] (barebox_non_pbl_start+0xc3/0x108) from [<2fd00005>] (__bare_init_start+0x1/0xc)

and related NULL pointer dereferences after 'dfu-util -e'.

Add a helper function which can be called by function drivers and
export the complete method.

*NOTE*: kernel uses the same code and probably suffers from the same
problem.

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
---
 drivers/usb/gadget/composite.c | 7 ++++++-
 include/linux/usb/composite.h  | 4 ++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index f55ae5698e08..98f7b5bf7fb4 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1509,7 +1509,7 @@ EXPORT_SYMBOL_GPL(usb_string_ids_n);
 
 /*-------------------------------------------------------------------------*/
 
-static void composite_setup_complete(struct usb_ep *ep, struct usb_request *req)
+void composite_setup_complete(struct usb_ep *ep, struct usb_request *req)
 {
 	struct usb_composite_dev *cdev;
 
@@ -1556,6 +1556,11 @@ static int composite_ep0_queue(struct usb_composite_dev *cdev,
 	return ret;
 }
 
+int composite_queue_setup_request(struct usb_composite_dev *cdev)
+{
+	return composite_ep0_queue(cdev, cdev->req);
+}
+
 static int count_ext_compat(struct usb_configuration *c)
 {
 	int i, res;
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index c3ee403abfe9..cc570657e55f 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -521,6 +521,10 @@ extern struct usb_string *usb_gstrings_attach(struct usb_composite_dev *cdev,
 
 extern int usb_string_ids_n(struct usb_composite_dev *c, unsigned n);
 
+extern void composite_setup_complete(struct usb_ep *ep,
+		struct usb_request *req);
+extern int composite_queue_setup_request(struct usb_composite_dev *cdev);
+
 extern void composite_disconnect(struct usb_gadget *gadget);
 extern void composite_reset(struct usb_gadget *gadget);
 
-- 
2.45.0