Messages in this thread Patch in this message | | | Date | Fri, 19 Nov 2010 13:56:36 -0800 | From | Greg KH <> | Subject | [75/82] net: add a recursion limit in xmit path |
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2.6.35-stable review patch. If anyone has any objections, please let us know.
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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);
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