USB: additional regression fix for device removal

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>
Cc: stable <stable@kernel.org>
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 (file)
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1147,6 +1147,14 @@ void usb_disable_device(struct usb_device *dev, int skip_ep0)
         * 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 @@ void usb_disable_device(struct usb_device *dev, int skip_ep0)
                                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);
                }