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Date: Sun, 12 Dec 2010 17:08:44 +0200
From: Shmulik Hen <shmulik@...go.co.il>
To: netdev@...r.kernel.org
Subject: System blocks (hangs) on ifconfig up
Hello,
My system is Ubuntu 10.04, running kernel 2.6.32-26-generic.
Whenever I try to bring up a specific ethernet interface for the second
time, my
system becomes unresponsive for 60 seconds - i.e. no mouse, no keyboard, no
screen refresh. etc.
Looking at the driver's code, I could see that it's dev->open() method
calls
wait_event_interruptible_timeout() with a timeout of 60 seconds - exactly
the delay I'm seeing.
I have narrowed the code to a bare minimum (see below - loosely based on
dummy.c), which only calls mdelay(10000) in it's dev->open() method, and
still, my system blocks for exactly 10 seconds when I run the following
sequence:
> sudo ifconfig shmulik0 up
> sudo ifconfig shmulik0 down
> sudo ifconfig shmulik0 up
At this point - the system is stuck for 10 seconds.
Thanks,
Shmulik.
------------------------------------------------------------------------------
shmulik.c:
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/skbuff.h>
MODULE_AUTHOR("Shmulik Hen");
MODULE_DESCRIPTION("Shmulik's sample network driver");
MODULE_LICENSE("GPL");
static struct net_device *g_dev = NULL;
static int shmulik_set_mac_address(struct net_device *dev, void *p)
{
struct sockaddr *sa = p;
if (!is_valid_ether_addr(sa->sa_data))
return -EADDRNOTAVAIL;
memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN);
return 0;
}
static netdev_tx_t shmulik_start_xmit(struct sk_buff *skb, struct
net_device *dev)
{
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
static int shmulik_open(struct net_device *dev)
{
mdelay(10000);
netif_carrier_on(dev);
netif_start_queue(dev);
return 0;
}
static int shmulik_close(struct net_device *dev)
{
netif_stop_queue(dev);
netif_carrier_off(dev);
return 0;
}
static const struct net_device_ops shmulik_drv_ops =
{
.ndo_open = shmulik_open,
.ndo_stop = shmulik_close,
.ndo_start_xmit = shmulik_start_xmit,
.ndo_set_mac_address = shmulik_set_mac_address,
};
static int __init shmulik_drv_init(void)
{
int rc;
struct net_device *dev;
if (g_dev)
return -EEXIST;
dev = alloc_etherdev(0);
if (!dev)
return -ENOMEM;
sprintf(dev->name, "%s%d" , "shmulik", 0);
dev->tx_queue_len = 0;
dev->flags |= IFF_NOARP;
dev->flags &= ~IFF_MULTICAST;
random_ether_addr(dev->dev_addr);
dev->netdev_ops = &shmulik_drv_ops;
rc = register_netdev(dev);
if (rc)
goto err_exit;
g_dev = dev;
return 0;
err_exit:
free_netdev(dev);
return rc;
}
static void __exit shmulik_drv_exit(void)
{
if (g_dev)
{
unregister_netdev(g_dev);
free_netdev(g_dev);
g_dev = NULL;
}
}
module_init(shmulik_drv_init);
module_exit(shmulik_drv_exit);
--
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