On Thu, Jul 07, 2011 at 03:38:49PM +0200, Stefan Richter wrote:
> On Jul 07 Stefan Richter wrote:
> > It appears to be a regression from -rc4 to -rc6. At the second occasion
> > that I switched the monitor off while running 3.0-rc6, the same happened
> > again. (IOW judging from the mere two tries I did so far, this issue is
> > 100% reproducible.)
> >
> > khubd locked up; no subsequent device re-attachments were recognized;
> > only an USB mouse that was attached to a motherboard USB port already
> > before the deadlock continued to let me move the pointer.
>
> Sarah, "gitk v3.0-rc4.. drivers/usb/core/" makes it look like this is from
> commit fccf4e86200b8f5edd9a65da26f150e32ba79808. When I find spare time I
> will test 3.0-rc6 with that one reverted.
Can you test Linus's tree, along with a patch sent yesterday from Alan
Stern to the linux-usb mailing list (attached below)? That should
resolve this issue, if not, please let us know.
thanks,
greg k-h
>From stern+4e0774f0@xxxxxxxxxxxxxxxxxxx Wed Jul 6 14:03:47 2011
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Date: Wed, 6 Jul 2011 17:03:45 -0400 (EDT)
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
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To: Greg KH <gregkh@xxxxxxx>
Cc: Arkadiusz Miskiewicz <a.miskiewicz@xxxxxxxxx>,
=?iso-8859-1?Q?=C9ric?= Piel <E.A.B.Piel@xxxxxxxxxx>,
Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>,
LKML <linux-kernel@xxxxxxxxxxxxxxx>,
USB list <linux-usb@xxxxxxxxxxxxxxx>,
"Rafael J. Wysocki" <rjw@xxxxxxx>
Subject: [PATCH] USB: additional regression fix for device removal
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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 <stern@xxxxxxxxxxxxxxxxxxx>
CC: <stable@xxxxxxxxxx>
---
This should take care of Eric's problem as well as Arkadiusz, since
they seemed to be hitting the same thing (cdc_ether claiming multiple
interfaces and hanging while releasing them).
Still, we need to rewrite this stuff. A possible race remains, because
a driver may try to change an altsetting at the same time as the device
is removed. Either the driver's disconnect routine would hang waiting
for the altsetting change (which is waiting to acquire the
bandwidth_mutex) or else the altsetting change would go through after
the driver was unbound from the device. Neither alternative is good.
Alan Stern
drivers/usb/core/message.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
Index: usb-3.0/drivers/usb/core/message.c
===================================================================
--- usb-3.0.orig/drivers/usb/core/message.c
+++ usb-3.0/drivers/usb/core/message.c
@@ -1147,6 +1147,14 @@ void usb_disable_device(struct usb_devic
* 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_devic
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);
}
