| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <7866DA1F8D2D4541B87FEE88E633ABAA2B72081FB6@MNEXMB1.qlogic.org>
Date: Thu, 5 Aug 2010 09:20:03 -0500
From: Usha Srinivasan <usha.srinivasan@...gic.com>
To: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Receive processing stops when dev->poll returns 1
Hello,
I have run into an interesting and frustrating problem which I've not been able to resolve. I am hoping someone can help me.
I have a network driver which sets its dev->weight to 100 (like ipoib) and when it processes 100 received packets, following the rules, it decrements dev->quota and *budget and returns 1 without calling netif_rx_complete. When my driver does that, all processing of incoming packets for all interfaces comes to a halt.
How do I know this? Because, as soon as my driver returns 1 to dev->poll, I lose my putty session and eth0 stops working; eth0 counters show that it stops receiving packets, though it is able to transmit. My own device stops receiving packets. I have scoured the code for ipoib and other network devices and I see no difference in what my driver does. I have tried to lower weight for ipoib & eth0 hoping to reproduce with those device it but no luck.
One guess is that net_rx_action spent more than 1 tick processing all the incoming packets for all interfaces it polled; I verified that my driver by itself does not spend that much. When this happens, net_rx_action exits after marking NETIF_RX_SOFTIRQ as pending. So one would expect it to be called again later, but my guess is that doesn't happen thereby resulting in a stoppage of incoming packets. Is that possible and, if so, what is the fix?
1814 static void net_rx_action(struct softirq_action *h)
1815 {
1816 struct softnet_data *queue = &__get_cpu_var(softnet_data);
1817 unsigned long start_time = jiffies;
1818 int budget = netdev_budget;
1819 void *have;
1820
1821 local_irq_disable();
1822
1823 while (!list_empty(&queue->poll_list)) {
1824 struct net_device *dev;
1825
1826 if (budget <= 0 || jiffies - start_time > 1)
1827 goto softnet_break;
1828
1829 local_irq_enable();
1830
1831 dev = list_entry(queue->poll_list.next,
1832 struct net_device, poll_list);
1833 have = netpoll_poll_lock(dev);
1834
1835 if (dev->quota <= 0 || dev->poll(dev, &budget)) {
1836 netpoll_poll_unlock(have);
1837 local_irq_disable();
1838 list_move_tail(&dev->poll_list, &queue->poll_list);
1839 if (dev->quota < 0)
1840 dev->quota += dev->weight;
1841 else
1842 dev->quota = dev->weight;
1843 } else {
1844 netpoll_poll_unlock(have);
1845 dev_put(dev);
1846 local_irq_disable();
1847 }
1848 }
1849 out:
1850 local_irq_enable();
1851 return;
1852
1853 softnet_break:
1854 __get_cpu_var(netdev_rx_stat).time_squeeze++;
1855 __raise_softirq_irqoff(NET_RX_SOFTIRQ);
1856 goto out;
1857 }
1858
I have run into this problem on four systems running RHEL5, SLES10 or SLES 11. The above describes what happens in RHEL5/SLES10. This is different in SLES11, wherein dev->poll has been replaced by netif_napi_add and the poll function returns done without quota/budget manipulation; yet, I run into the same behavior.
Any help appreciated! Thanks in advance!
Usha
___________________
Usha Srinivasan
Software Engineer
QLogic Corporation
780 5th Ave, Suite A
King of Prussia, PA 19406
(610) 233-4844
(610) 233-4777 (Fax)
(610) 233-4838 (Main Desk)
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists