linux-kernel - [PATCH v3] usb: gadget: composite: Show warning if function driver's descriptors are incomplete.

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Message-Id: <20211109101936.397503-1-huqihang@oppo.com>
Date:   Tue,  9 Nov 2021 18:19:36 +0800
From:   Qihang Hu <huqihang@...o.com>
To:     balbi@...nel.org, gregkh@...uxfoundation.org, peter.chen@...nel.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Qihang Hu <huqihang@...o.com>
Subject: [PATCH v3] 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 unsound function drivers may
not support the corresponding speed. So, we can directly display
warnings instead of panicking the kernel. At the same time, it
indicates a problem with the function in the warning message.

Signed-off-by: Qihang Hu <huqihang@...o.com>
---
Changes in v2:
-Add warning message

Changes in v3:
-Change commit log
-Delete extra blank lines
-Modify 'incomplete_desc' to bool type
---
 drivers/usb/gadget/composite.c | 39 ++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 72a9797dbbae..cb9c7edf9bbf 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 @@ int config_ep_by_speed_and_alt(struct usb_gadget *g,
 			_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;
 		}
-- 
2.25.1