[PATCH 1/2] usbcore: Check both id_table and match() when both available

From: "M. Vefa Bicakci" <m.v.b@runbox.com>
To: linux-usb@vger.kernel.org
Cc: Bastien Nocera <hadess@hadess.net>,
	stable@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	"M . Vefa Bicakci" <m.v.b@runbox.com>
Subject: [PATCH 1/2] usbcore: Check both id_table and match() when both available
Date: Thu, 22 Oct 2020 09:55:20 -0400	[thread overview]
Message-ID: <20201022135521.375211-2-m.v.b@runbox.com> (raw)
In-Reply-To: <20201022135521.375211-1-m.v.b@runbox.com>

From: Bastien Nocera <hadess@hadess.net>

From: Bastien Nocera <hadess@hadess.net>

When a USB device driver has both an id_table and a match() function, make
sure to check both to find a match, first matching the id_table, then
checking the match() function.

This makes it possible to have module autoloading done through the
id_table when devices are plugged in, before checking for further
device eligibility in the match() function.

Signed-off-by: Bastien Nocera <hadess@hadess.net>
Cc: <stable@vger.kernel.org> # 5.8
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Co-developed-by: M. Vefa Bicakci <m.v.b@runbox.com>
Signed-off-by: M. Vefa Bicakci <m.v.b@runbox.com>
---
 drivers/usb/core/driver.c  | 30 +++++++++++++++++++++---------
 drivers/usb/core/generic.c |  4 +---
 drivers/usb/core/usb.h     |  2 ++
 3 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 98b7449c11f3..4dfa44d6cc3c 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -839,6 +839,22 @@ const struct usb_device_id *usb_device_match_id(struct usb_device *udev,
 	return NULL;
 }
 
+bool usb_driver_applicable(struct usb_device *udev,
+			   struct usb_device_driver *udrv)
+{
+	if (udrv->id_table && udrv->match)
+		return usb_device_match_id(udev, udrv->id_table) != NULL &&
+		       udrv->match(udev);
+
+	if (udrv->id_table)
+		return usb_device_match_id(udev, udrv->id_table) != NULL;
+
+	if (udrv->match)
+		return udrv->match(udev);
+
+	return false;
+}
+
 static int usb_device_match(struct device *dev, struct device_driver *drv)
 {
 	/* devices and interfaces are handled separately */
@@ -853,17 +869,14 @@ static int usb_device_match(struct device *dev, struct device_driver *drv)
 		udev = to_usb_device(dev);
 		udrv = to_usb_device_driver(drv);
 
-		if (udrv->id_table)
-			return usb_device_match_id(udev, udrv->id_table) != NULL;
-
-		if (udrv->match)
-			return udrv->match(udev);
-
 		/* If the device driver under consideration does not have a
 		 * id_table or a match function, then let the driver's probe
 		 * function decide.
 		 */
-		return 1;
+		if (!udrv->id_table && !udrv->match)
+			return 1;
+
+		return usb_driver_applicable(udev, udrv);
 
 	} else if (is_usb_interface(dev)) {
 		struct usb_interface *intf;
@@ -941,8 +954,7 @@ static int __usb_bus_reprobe_drivers(struct device *dev, void *data)
 		return 0;
 
 	udev = to_usb_device(dev);
-	if (usb_device_match_id(udev, new_udriver->id_table) == NULL &&
-	    (!new_udriver->match || new_udriver->match(udev) == 0))
+	if (!usb_driver_applicable(udev, new_udriver))
 		return 0;
 
 	ret = device_reprobe(dev);
diff --git a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c
index 22c887f5c497..26f9fb9f67ca 100644
--- a/drivers/usb/core/generic.c
+++ b/drivers/usb/core/generic.c
@@ -205,9 +205,7 @@ static int __check_for_non_generic_match(struct device_driver *drv, void *data)
 	udrv = to_usb_device_driver(drv);
 	if (udrv == &usb_generic_driver)
 		return 0;
-	if (usb_device_match_id(udev, udrv->id_table) != NULL)
-		return 1;
-	return (udrv->match && udrv->match(udev));
+	return usb_driver_applicable(udev, udrv);
 }
 
 static bool usb_generic_driver_match(struct usb_device *udev)
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h
index c893f54a3420..82538daac8b8 100644
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -74,6 +74,8 @@ extern int usb_match_device(struct usb_device *dev,
 			    const struct usb_device_id *id);
 extern const struct usb_device_id *usb_device_match_id(struct usb_device *udev,
 				const struct usb_device_id *id);
+extern bool usb_driver_applicable(struct usb_device *udev,
+				  struct usb_device_driver *udrv);
 extern void usb_forced_unbind_intf(struct usb_interface *intf);
 extern void usb_unbind_and_rebind_marked_interfaces(struct usb_device *udev);
 
-- 
2.26.2

