On 7/1/06, Arjan van de Ven <[email protected]> wrote:
On Fri, 2006-06-30 at 15:45 -0700, Miles Lane wrote:
> Okay, I rebuilt my kernel with your combo patch applied.
> Then, I inserted my US Robotics USR2210 PCMCIA wifi card,
> ran "pccardutil eject", popped out the card and then inserted
> a Compaq iPaq wifi card. This triggered the following.
>
> [ INFO: possible circular locking dependency detected ]
> -------------------------------------------------------
> syslogd/1886 is trying to acquire lock:
> (&dev->queue_lock){-+..}, at: [<c11a50b5>] dev_queue_xmit+0x120/0x24b
>
> but task is already holding lock:
> (&dev->_xmit_lock){-+..}, at: [<c11a5118>] dev_queue_xmit+0x183/0x24b
>
> which lock already depends on the new lock.
ok this appears to be hostap playing games... it has 2 network devices
for one piece of hardware and one calls the other via the networking
layer; there is thankfully a natural ordering between the two, so just
making the slave one a separate type ought to make this work.
Can you test the patch below?
---
drivers/net/wireless/hostap/hostap_hw.c | 10 ++++++++++
1 file changed, 10 insertions(+)
Index: linux-2.6.17-mm4/drivers/net/wireless/hostap/hostap_hw.c
===================================================================
--- linux-2.6.17-mm4.orig/drivers/net/wireless/hostap/hostap_hw.c
+++ linux-2.6.17-mm4/drivers/net/wireless/hostap/hostap_hw.c
@@ -3096,6 +3096,14 @@ static void prism2_clear_set_tim_queue(l
}
+/*
+ * HostAP uses two layers of net devices, where the inner
+ * layer gets called all the time from the outer layer.
+ * This is a natural nesting, which needs a split lock type.
+ */
+static struct lock_class_key hostap_netdev_xmit_lock_key;
+
+
static struct net_device *
prism2_init_local_data(struct prism2_helper_functions *funcs, int card_idx,
struct device *sdev)
@@ -3260,6 +3268,8 @@ while (0)
SET_NETDEV_DEV(dev, sdev);
if (ret >= 0)
ret = register_netdevice(dev);
+
+ lockdep_set_class(&dev->_xmit_lock, &hostap_netdev_xmit_lock_key);
rtnl_unlock();
if (ret < 0) {
printk(KERN_WARNING "%s: register netdevice failed!\n",
(Sorry for the duplicate message Arjan, I forgot to Reply All the first time.)
After rebuilding with this patch, I still get the lockdep message.
Everything is the same except now the "other info" section reads:
other info that might help us debug this:
1 lock held by swapper/0:
#0: (&dev->_xmit_lock){-+..}, at: [<c11a5118>] dev_queue_xmit+0x183/0x24b
-
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