2.6.35-stable review patch. If anyone has any objections, please let us know.
------------------
From: Eric Dumazet <eric.dumazet@gmail.com>
[ Upstream commits 745e20f1b626b1be4b100af5d4bf7b3439392f8f and
11a766ce915fc9f8663714eac6d59239388534ea ]
As tunnel devices are going to be lockless, we need to make sure a
misconfigured machine wont enter an infinite loop.
Add a percpu variable, and limit to three the number of stacked xmits.
Reported-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
net/core/dev.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2110,6 +2110,9 @@ static inline int skb_needs_linearize(st
illegal_highdma(dev, skb)));
}
+static DEFINE_PER_CPU(int, xmit_recursion);
+#define RECURSION_LIMIT 10
+
/**
* dev_queue_xmit - transmit a buffer
* @skb: buffer to transmit
@@ -2194,10 +2197,15 @@ gso:
if (txq->xmit_lock_owner != cpu) {
+ if (__this_cpu_read(xmit_recursion) > RECURSION_LIMIT)
+ goto recursion_alert;
+
HARD_TX_LOCK(dev, txq, cpu);
if (!netif_tx_queue_stopped(txq)) {
+ __this_cpu_inc(xmit_recursion);
rc = dev_hard_start_xmit(skb, dev, txq);
+ __this_cpu_dec(xmit_recursion);
if (dev_xmit_complete(rc)) {
HARD_TX_UNLOCK(dev, txq);
goto out;
@@ -2209,7 +2217,9 @@ gso:
"queue packet!\n", dev->name);
} else {
/* Recursion is detected! It is possible,
- * unfortunately */
+ * unfortunately
+ */
+recursion_alert:
if (net_ratelimit())
printk(KERN_CRIT "Dead loop on virtual device "
"%s, fix it urgently!\n", dev->name);
--
