This is a note to let you know that I've just added the patch titled
USB: additional regression fix for device removal
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6.git
in the usb-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also will be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From ca5c485f55d326d9a23e4badd05890148aa53f74 Mon Sep 17 00:00:00 2001
From: Alan Stern <[email protected]>
Date: Wed, 6 Jul 2011 17:03:45 -0400
Subject: USB: additional regression fix for device removal
MIME-Version: 1.0
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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 <[email protected]>
Cc: stable <[email protected]>
Tested-by: Ãric Piel <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/usb/core/message.c | 9 ++++++++-
1 files changed, 8 insertions(+), 1 deletions(-)
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 @@ 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);
}
--
1.7.6
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