lkml.org 
[lkml]   [2010]   [Nov]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[75/82] net: add a recursion limit in xmit path
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);



\
 
 \ /
  Last update: 2010-11-19 23:05    [W:0.021 / U:5.360 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site