usb: gadget: composite: Show warning if function driver's descriptors are incomplete.

In the config_ep_by_speed_and_alt function, select the corresponding
descriptor through g->speed. But some legacy or not well designed
function drivers may not support the corresponding speed. So, we can
directly display warnings instead of causing kernel panic. At the
same time, it indicates the reasons in warning message.

Reviewed-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Qihang Hu <huqihang@oppo.com>
Link: https://lore.kernel.org/r/20211110101129.462357-1-huqihang@oppo.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 26 insertions, 13 deletions

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 504c1cbc255d..c5528e037a37 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -159,6 +159,8 @@ int config_ep_by_speed_and_alt(struct usb_gadget *g,
 	int want_comp_desc = 0;
 
 	struct usb_descriptor_header **d_spd; /* cursor for speed desc */
+	struct usb_composite_dev *cdev;
+	bool incomplete_desc = false;
 
 	if (!g || !f || !_ep)
 		return -EIO;
@@ -167,28 +169,43 @@ int config_ep_by_speed_and_alt(struct usb_gadget *g,
 	switch (g->speed) {
 	case USB_SPEED_SUPER_PLUS:
 		if (gadget_is_superspeed_plus(g)) {
-			speed_desc = f->ssp_descriptors;
-			want_comp_desc = 1;
-			break;
+			if (f->ssp_descriptors) {
+				speed_desc = f->ssp_descriptors;
+				want_comp_desc = 1;
+				break;
+			}
+			incomplete_desc = true;
 		}
 		fallthrough;
 	case USB_SPEED_SUPER:
 		if (gadget_is_superspeed(g)) {
-			speed_desc = f->ss_descriptors;
-			want_comp_desc = 1;
-			break;
+			if (f->ss_descriptors) {
+				speed_desc = f->ss_descriptors;
+				want_comp_desc = 1;
+				break;
+			}
+			incomplete_desc = true;
 		}
 		fallthrough;
 	case USB_SPEED_HIGH:
 		if (gadget_is_dualspeed(g)) {
-			speed_desc = f->hs_descriptors;
-			break;
+			if (f->hs_descriptors) {
+				speed_desc = f->hs_descriptors;
+				break;
+			}
+			incomplete_desc = true;
 		}
 		fallthrough;
 	default:
 		speed_desc = f->fs_descriptors;
 	}
 
+	cdev = get_gadget_data(g);
+	if (incomplete_desc)
+		WARNING(cdev,
+			"%s doesn't hold the descriptors for current speed\n",
+			f->name);
+
 	/* find correct alternate setting descriptor */
 	for_each_desc(speed_desc, d_spd, USB_DT_INTERFACE) {
 		int_desc = (struct usb_interface_descriptor *)*d_spd;
@@ -244,12 +261,8 @@ ep_found:
 			_ep->maxburst = comp_desc->bMaxBurst + 1;
 			break;
 		default:
-			if (comp_desc->bMaxBurst != 0) {
-				struct usb_composite_dev *cdev;
-
-				cdev = get_gadget_data(g);
+			if (comp_desc->bMaxBurst != 0)
 				ERROR(cdev, "ep0 bMaxBurst must be 0\n");
-			}
 			_ep->maxburst = 1;
 			break;
 		}