USB: additional regression fix for device removal
commit ca5c485f55d326d9a23e4badd05890148aa53f74 upstream.
Commit e534c5b831c8b8e9f5edee5c8a37753c808b80dc (USB: fix regression
occurring during device removal) didn't go far enough. It failed to
take into account that when a driver claims multiple interfaces, it may
release them all at the same time. As a result, some interfaces can
get released before they are unregistered, and we deadlock trying to
acquire the bandwidth_mutex that we already own.
This patch (asl478) handles this case by setting the "unregistering"
flag on all the interfaces before removing any of them.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Éric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index e0719b4..0b5ec23 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1147,6 +1147,14 @@
* any drivers bound to them (a key side effect)
*/
if (dev->actconfig) {
+ /*
+ * FIXME: In order to avoid self-deadlock involving the
+ * bandwidth_mutex, we have to mark all the interfaces
+ * before unregistering any of them.
+ */
+ for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++)
+ dev->actconfig->interface[i]->unregistering = 1;
+
for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
struct usb_interface *interface;
@@ -1156,7 +1164,6 @@
continue;
dev_dbg(&dev->dev, "unregistering interface %s\n",
dev_name(&interface->dev));
- interface->unregistering = 1;
remove_intf_ep_devs(interface);
device_del(&interface->dev);
}
