[PATCH v4] usb: prevent duplicate bEndpointAddress by usb_ep_autoconfig_ss (bitmap).

[Wlodzimierz Lipert <wlodzimierz.lipert@gmail.com>]

usb_ep_autoconfig_ss tries to use endpoint name or internal counters to generate
bEndpointAddress - this leads to duplicate addresses. Fix changes the
way in/out_epnum is used, now as bitmap which represents unavailable ep numbers.

v2: formatting fixes only (errors).
v3: refined autoconf logic (removed num_mask, switched to use ffz).
v4: formatting only changes (style).

Signed-off-by: Wlodzimierz Lipert <wlodzimierz.lipert@gmail.com>
---
 drivers/usb/gadget/epautoconf.c | 25 ++++++++++++++++---------
 include/linux/usb/gadget.h      |  4 ++--
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/gadget/epautoconf.c b/drivers/usb/gadget/epautoconf.c
index 1eb4fa2e623f..f73a7fe3d7d7 100644
--- a/drivers/usb/gadget/epautoconf.c
+++ b/drivers/usb/gadget/epautoconf.c
@@ -67,6 +67,8 @@ struct usb_ep *usb_ep_autoconfig_ss(
 )
 {
 	struct usb_ep	*ep;
+	unsigned	*epmap;
+	u8		num;
 
 	if (gadget->ops->match_ep) {
 		ep = gadget->ops->match_ep(gadget, desc, ep_comp);
@@ -93,19 +95,23 @@ struct usb_ep *usb_ep_autoconfig_ss(
 
 	/* report address */
 	desc->bEndpointAddress &= USB_DIR_IN;
+	epmap = usb_endpoint_dir_in(desc) ?
+			&gadget->in_epnum : &gadget->out_epnum;
+
 	if (isdigit(ep->name[2])) {
-		u8 num = simple_strtoul(&ep->name[2], NULL, 10);
-		desc->bEndpointAddress |= num;
-	} else if (desc->bEndpointAddress & USB_DIR_IN) {
-		if (++gadget->in_epnum > 15)
+		num = simple_strtoul(&ep->name[2], NULL, 10);
+		WARN_ON(num == 0 || num > 15);
+		if (*epmap & (1U << num))
 			return NULL;
-		desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
 	} else {
-		if (++gadget->out_epnum > 15)
+		/* find first available ep number (not encoded in ep name) */
+		num = ffz(*epmap);
+		if (num > 15)
 			return NULL;
-		desc->bEndpointAddress |= gadget->out_epnum;
 	}
 
+	*epmap |= 1U << num;
+	desc->bEndpointAddress |= num;
 	ep->address = desc->bEndpointAddress;
 	ep->desc = NULL;
 	ep->comp_desc = NULL;
@@ -208,7 +214,8 @@ void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
 		ep->claimed = false;
 		ep->driver_data = NULL;
 	}
-	gadget->in_epnum = 0;
-	gadget->out_epnum = 0;
+	/* ep num 0 is reserved: not available for auto configuration */
+	gadget->in_epnum = 1U;
+	gadget->out_epnum = 1U;
 }
 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 6a178177e4c9..1e00e22202bc 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -343,8 +343,8 @@ struct usb_gadget_ops {
  *	and sometimes configuration.
  * @dev: Driver model state for this abstract device.
  * @isoch_delay: value from Set Isoch Delay request. Only valid on SS/SSP
- * @out_epnum: last used out ep number
- * @in_epnum: last used in ep number
+ * @out_epnum: bitmap of allocated out ep numbers
+ * @in_epnum: bitmap of allocated in ep numbers
  * @mA: last set mA value
  * @otg_caps: OTG capabilities of this gadget.
  * @sg_supported: true if we can handle scatter-gather
-- 
2.39.2